JPH06266194A - Image forming device - Google Patents

Abstract

PURPOSE:To precisely detect the surface potential of a photosensitive drum by a potential sensor. CONSTITUTION:A traveling truck 31 is moved along a traveling rail 41 laid along the generatrix direction of the surface of a photosensitive drum 2. In the traveling truck 31, a sensor fixing plate 33 is attached to a moving base 32 via a compression spring 36. Four roller supporting bodies 51 are fixed on the sensor fixing plate 33 and abutting rollers 52 are held by each roller supporting body 51. Further, a potential sensor 35 is mounted on the sensor fixing base 33, so that a measuring part 35a oppositely faces the surface of the photosensitive drum 2. Since the abutting roller 52 is abutted on the surface of the phtotosensitive drum 2 by the compression spring 36, a detection distance (x) between the surface of the pltotosensitive drum 2 and the measuring part 35a is always and precisely kept constant even if the photosensitive drum 2 has eccentricity, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, and a facsimile, and more specifically, detection for detecting the state of the surface of a photoconductor such as a potential sensor and a density sensor. Regarding means.

[0002]

[Prior art]

<Prior Art 1> Conventionally, for example, in an image forming apparatus such as a copying machine equipped with a cylindrical photosensitive drum as a photoconductor,
A technique for detecting the potential of the surface of the photosensitive drum and the density of the toner image on the photosensitive drum is known.

The outline of the image forming process by this copying machine is as follows. First, the surface of the photosensitive drum is uniformly charged by the charging device. Next, the uniformly charged surface of the photosensitive drum is exposed by an exposure device to form an electrostatic latent image. Subsequently, the developing device attaches toner to the electrostatic latent image to form a toner image. The toner image on the photosensitive drum is transferred onto a transfer material by a transfer device. Finally, the fixing device fixes the toner image on the transfer material to the transfer material to form an image.

In the above-mentioned image forming process, in order to finally obtain a good image, for example, it is necessary to form a suitable electrostatic latent image by a charging device and an exposure device and a suitable development by a developing device. is there.

Therefore, a potential sensor for detecting the potential of the photosensitive drum surface after charging and exposure, and a density sensor for detecting the density of the toner image formed on the photosensitive drum are provided, and based on these detection results. By controlling the charging device and the developing device, a high quality image is finally obtained.

The potential sensor and the density sensor are arranged so as to face the surface of the photosensitive drum with a slight distance therebetween, and are configured to move along the generatrix direction of the surface of the photosensitive drum. Furthermore, the rotation of the photosensitive drum is combined with the movement of these sensors in the generatrix direction, whereby these sensors can two-dimensionally scan the entire surface of the photosensitive drum to detect the surface condition.

The distance between these sensors and the surface of the photosensitive drum (hereinafter referred to as "detection distance") at the time of detecting the electric potential and the density is
It must be kept strictly constant. This is because in the potential sensor, the potential is calculated according to the theoretical formula of voltage conversion assuming that the detection distance between the potential sensor and the surface of the photosensitive drum is constant, and the error in the detection distance becomes a measurement error as it is. In the density sensor, the optical axis is adjusted so that the light emitting portion that irradiates the toner image with light and the light receiving portion that receives the reflected light from the toner image are adjusted in accordance with the most ideal distance. This is because, like the sensor, it is necessary to reduce the distance error as much as possible.

In order to satisfy these requirements, a potential sensor,
The density sensor is mounted on the scanning carriage, and a guide rail that is arranged in strict parallel to the axis of the photosensitive drum is attached.By moving the scanning carriage along this guide rail, the scanning rail is moved along the generatrix direction of the surface of the photosensitive drum. These sensors are moving. <Prior Art 2> Conventionally, in an image forming apparatus such as a copying machine or a laser beam printer, the state quantity in a direction substantially orthogonal to the rotation direction of the photoconductor (in the case where the photoconductor is a drum, the generatrix direction of its surface) Techniques for detecting the are known. For example, a means for measuring the charge distribution on the surface of the photoconductor in the direction of the generatrix, a means for measuring the amount of toner adhered on the surface of the photoconductor in the direction of the generatrix, and a method for measuring the density of the toner image after transfer onto the transfer material Means for measuring in a direction substantially orthogonal to the traveling direction. Further, a technique of recording these state quantities and reflecting them in process conditions such as charging, exposure, and development has been conventionally known. Here, the reflection in the process condition means that the state quantity in the generatrix direction of the surface of the photoconductor is measured, and a series of adjustment routines in which the adjustment amount is adjusted to optimize this are repeated, and the state quantity is gradually adjusted to an appropriate value. Is a method of approaching.

[0009]

[Problems to be Solved by the Invention]

<Problem of the first invention> However, according to the conventional technique 1, the scanning carriage equipped with the potential sensor and the density sensor is
Since the photosensitive drum surface is placed in a non-contact state with respect to the photosensitive drum surface, the photosensitive drum surface may be slightly eccentric or curved with respect to the photosensitive drum axis, and the assembly accuracy of the photosensitive drum, sensor, etc. may be poor. Alternatively, if the mechanical accuracy of the scanning carriage is insufficient, it is difficult to maintain the detection distance between the surface of the photosensitive drum and the sensor at a high accuracy and a constant, which causes a large measurement error.
It should be noted that such a measurement error occurs not only when the photosensitive member is a cylindrical photosensitive drum but also when the photosensitive member is a photosensitive belt, for example. That is, since the photosensitive belt is formed of a flexible member, it tends to be twisted or bent, which reduces the measurement accuracy.

Therefore, in the first invention, the surface of the photoconductor and the detector (potential sensor,
It is an object of the present invention to provide an image forming apparatus in which the surface state of a photoconductor is accurately detected by a detector by regulating the detection distance from the density sensor. <Problem of the Second Invention> Further, according to the conventional technique 2, in the method of repeating the series of adjustment routines for optimizing the state quantity of the photoconductor, the measurement time is greatly increased. Use was restricted. For example, it takes about 30 seconds to measure the state quantity in all areas at one time, and if this is repeated 4 times for adjustment, at least 2 minutes or more is required. There was a problem that it was limited to execution only within.

Therefore, the second aspect of the present invention provides an image forming apparatus in which the measuring time is greatly reduced by adjusting the state quantity based on the storage means that associates the measuring position of the detector with the state quantity. The purpose is to do.

[0012]

The present invention (first invention and second invention) has been made in view of the above circumstances, and has the following configurations. <Means of the First Invention> A first invention is a charging device for uniformly charging a photoconductor, an exposure device for exposing the photoconductor to form an electrostatic latent image, and an electrostatic latent image for the electrostatic latent image. In the image forming apparatus, the image forming apparatus includes: a developing device that forms a toner image by adhering toner; a transfer device that transfers the toner image onto a transfer material; and a detection unit that detects the state of the surface of the photoconductor. A scanning carriage arranged to be movable along a generatrix of the surface of the photoconductor; a driving means for moving the scanning carriage; and a detection unit mounted on the scanning carriage for detecting the state of the surface of the photoconductor. And a scanning cart,
A spacer that contacts the surface of the photoconductor and maintains a constant detection distance between the surface of the photoconductor and the detector; and a biasing member that presses the spacer against the surface of the photoconductor.
It is characterized by

In this case, the scanning carriage may have a cleaning member for cleaning the spacer.

The detector is a potential sensor for detecting the potential on the surface of the photoconductor, and the potential sensor is downstream of the charging device and upstream of the developing device in the rotating direction of the photoconductor. Is a density sensor that is disposed on the side of the photoconductor, or is a density sensor that detects the density of a toner image formed on the surface of the photoconductor, and the density sensor is downstream of the developing device in the rotation direction of the photoconductor, and It may be arranged on the upstream side of the transfer device.

Further, regarding the rotation direction of the photoconductor,
A charge eliminating system for changing the charge amount of the photoconductor can be arranged on the upstream side of the contact area of the spacer.

In addition, the photosensitive member is a photosensitive belt formed in a belt shape, the spacer contacts the surface of the photosensitive belt, and the position of the photosensitive belt is regulated on the back side of the contact portion. You may make it have a base member which does. <Means of Second Invention> A second invention is a charging device for uniformly charging a photoconductor, an exposure device for exposing the photoconductor to form an electrostatic latent image, and the electrostatic latent image. An image forming apparatus comprising: a developing device that forms a toner image by attaching toner to an image; a transfer device that transfers the toner image onto a transfer material; and a detection unit that detects the state of the surface of the photoconductor,
The detector is a detector arranged so as to be movable along the generatrix direction of the surface of the photoconductor, a positioning unit for positioning the detector, and a measurement position of the detector determined by the positioning unit. A storage means for associating the detection result of the detector at the measurement position with each other, and an adjusting means for adjusting the state quantity in the generatrix direction of the photoconductor surface based on the storage of the storage means. .

There may be arithmetic means for associating the state quantity of the surface of the photoconductor with the adjustment amount of the adjusting means, wherein the arithmetic means is an average value of the state quantity of the photoconductor in the generatrix direction,
The maximum value and the slope may be calculated.

The state quantity detected by the detecting means is the surface potential of the photoconductor. In this case, the surface potential of the photoconductor is a fully charged state, a charged state after exposure to an intermediate amount of light,
At least one of the charged states after complete exposure is measured.

The state quantity detected by the detection means is the toner concentration on the photoconductor or the transfer material. In this case, the toner concentration is the dark toner concentration on the photoconductor or the transfer material, the intermediate level. It is characterized in that at least one of the tone toner density and the light portion toner density is measured.

Further, the amount of state adjusted by the adjusting means may be the amount of charge of the photoconductor, the amount of exposure to the photoconductor, the amount of developing toner adhering to the photoconductor or the transfer material.

The adjusting means can change the adjustment amount so that the detector after the state amount measurement moved to the predetermined position obtains the predetermined state amount.

[0022]

[Action]

<Operation of the First Invention> Based on the above configuration, the spacer for keeping the detection distance between the photosensitive member surface and the detector constant is
Even when the detection means moves, the biasing member always contacts the surface of the photoconductor. That is, the spacer moves along the surface of the photoconductor even if the surface of the photoconductor is eccentric with respect to the axis of the photoconductor or has irregularities on the surface. Therefore, the detection distance between the surface of the photoconductor and the detector is accurately maintained, and the state of the surface of the photoconductor is accurately detected by the detector. <Operation of Second Invention> Further, according to the second invention, the measurement position of the detector with respect to the surface of the photoconductor and the state of the photoconductor surface are stored in association with each other, and the state quantity is adjusted based on this. Since the measurement is performed, the state quantity on the surface of the photoconductor can be accurately detected even if the number of measurement points by the detector is significantly reduced to shorten the measurement time.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1 of the first invention> FIG. 1 schematically shows a copying machine as an example of an image forming apparatus according to the first invention. This copying machine is provided with a cylindrical photosensitive drum 2 as a photoconductor in the substantial center of the apparatus main body 1. The photosensitive drum 2 is rotatably supported by the apparatus main body 1 in the direction of the arrow R1, and around the photosensitive drum 2, a static eliminator 3 for erasing the potential on the photosensitive drum 2 in order along the rotation direction thereof. Primary charger (charging device) that uniformly charges the surface of the photosensitive drum 2
5, an exposure device 6 that exposes the surface of the photosensitive drum 2 to form an electrostatic latent image, a developing device (developing device) 7 that attaches toner to the electrostatic latent image to form a toner image, and toner on the transfer material P. Transfer separation charger (transfer device) 9 for transferring an image, photosensitive drum 2
A cleaning device 10 for removing the upper residual toner is arranged.

The transfer material P, which is the transfer destination of the toner image, is supplied from the paper feed deck 11. A transfer path for the transfer material P is formed below the photosensitive drum 2, that is, a lower part inside the apparatus main body 1, and a paper feed deck for storing the transfer material P is provided on the most upstream side (right side in FIG. 1). 11 are arranged. The transfer material P in the paper feed deck 11 is fed by the paper feed roller 12 and passes through the conveyance roller 13 and the registration roller 15.
It is supplied between the photosensitive drum 2 and the transfer separation charger 9.
The toner image is transferred from the photosensitive drum 2 to the transfer material P, and the transfer material P is transported to the fixing device 17 by the transport belt 16. The transfer material P on which the toner image is transferred by the fixing device 17
Is discharged onto the discharge tray 20 by the discharge roller 19 as a final copy.

In the above copying machine, the exposing means 6 is
A document placed on the platen glass 21 is illuminated by a document illumination lamp 22 and a reflecting plate 23, and reflected light from the document image is further reflected by mirrors 25a, 25b, 25c and passed through a magnification / reduction lens 26. After the projection mirror 2
It is guided to the surface of the photosensitive drum 2 via 7. As a result, the surface of the uniformly charged photosensitive drum 2 is exposed to form an electrostatic latent image corresponding to the original image.

A standard density plate 29 is arranged near one end of the platen glass 21 (on the left side in the figure), and the exposure means 6 illuminates the original when measuring the surface potential of the photosensitive drum 2 and the density. The lamp 22 and the reflection plate 23 can be moved to a position where the standard density plate 29 can be irradiated.

FIG. 2 shows the structure of the standard density plate 29. The "front side" and the "back side" in the figure indicate the front side and the back side when the copying machine is viewed in the state of FIG. A in the figure
A black solid portion between B, a white solid portion between BC, and a halftone portion between CD can uniformly project the respective light amounts onto the photosensitive drum 2. The area between DEs is divided into a halftone band area and a white area in the halftone chart portion. The area between the EFs is a black chart portion, which is divided into a black band-shaped area and a white area.

The photosensitive drum 2 is provided between the developing device 7 and the exposure position of the exposing means 6 on the surface of the photosensitive drum 2.
A scanning type electric potential sensor unit 30 is arranged as a detecting means for detecting the surface condition, and measures the electric potential of the surface of the photosensitive drum 2.

FIG. 3 shows details of the scanning potential sensor unit 30. The scanning potential sensor unit 30 includes a scanning carriage 31 that moves along a scanning rail 41.
The scanning rail 41 is formed by a channel member having a substantially C-shaped cross section, and is laid along the generatrix direction of the surface of the photosensitive drum 2. The scanning rail 41 has a linear opening on the side facing the surface of the photosensitive drum 2, and a guide surface 41a formed inside. Scan rail 41
Are supported by a bent support base 42 fixed to the apparatus body (not shown). A rack 43 is attached to the tip of the support table 42 in a state of being parallel to the scanning rail 41.

The scanning carriage 31 is guided by the guide surface 41a of the scanning rail 41 and slides on the moving base 3.
2 and a sensor fixing base 33 on which a potential sensor (detector) 35 is mounted. The moving base 32 and the sensor fixing base 33 are connected by a compression spring (biasing member) 36. A stepping motor (driving means) 37 is mounted on the moving base 32, and its output shaft 37 is mounted.
A pinion 39 that meshes with the rack 43 is fixed to a. When the stepping motor 37 rotates,
The pinion 39 rotates in a state of meshing with the rack 43, whereby the scanning carriage 31 moves along the scanning rail 41.

On the other hand, the photosensitive drum 2 of the sensor fixing base 33
2 rows in the circumferential direction on the surface of the photosensitive drum 2,
Further, a total of four roller support receivers 51 arranged in two lines in the generatrix direction are attached. Each roller support receiver 51 is formed in a substantially cylindrical shape, and a recess for supporting a contact roller 52, which will be described later, is formed on the tip end side. A total of four spherical contact rollers (spacers) 52 are rotatably supported by these roller support receivers 51 (however, in FIG. 3 and FIG. 4 which is a view taken along the line A in FIG. 3). , Only the two front contact rollers 52 are shown.). Each contact roller 52
Is supported so that its contact portion 52a projects from the tip of each roller support receiver 51.
It is in contact with the surface. Further, the potential sensor 35 is fixed in the center of the surface of the sensor fixing base 33 facing the surface of the photosensitive drum 2, that is, between the four contact rollers 52. In the electric potential sensor 35, the measuring portion 35a at the tip has a contact roller 52
At a position slightly lower than the contact portion, that is, when the contact roller 52 contacts the surface of the photosensitive drum 2.
It is arranged at a position where a predetermined detection distance x is formed between a and the surface of the photosensitive drum 2. This detection distance x
Is always constant. That is, as described above, the sensor fixing base 33 is urged toward the photosensitive drum 2 by the compression spring 36, and the contact roller 52 comes into contact with the surface of the photosensitive drum 2 so that the surface of the photosensitive drum 2 is removed. The position of is regulated accurately. On the other hand, the potential sensor 35 is fixed to the sensor fixing base 33 whose position is accurately regulated, and has an integral structure. Therefore, as long as the contact roller 52 is in contact with the surface of the photosensitive drum 2, the detection distance x from the surface of the photosensitive drum 2 to the measuring portion 35a of the potential sensor 35 is kept constant. Further, a fur brush (cleaning member) 55 that comes into contact with the surface of the contact roller 52 is arranged inside the roller support base 51 to remove toner, dust, etc. adhering to the surface of the contact roller 52. By the adhesion of the toner and dust to the roller member 52, the detection distance x between the surface of the photosensitive drum 2 and the measuring portion 35a of the potential sensor 35 x.
Is prevented from changing subtly.

Further, an LED lamp (static elimination system) 56 is fixed to the roller support base 33. The LED lamps 56 are arranged in the circumferential direction of the photosensitive drum 2 and contact the roller 5
2. The surface of the photosensitive drum 2 is required so that the contact roller 52 does not come into contact with the surface of the photosensitive drum 2 which is located at the upstream side of the contact area 2 (with respect to the rotation direction of the photosensitive drum 2) and remains charged. Part of the charge is being removed. The light quantity distribution of the lamp is narrowed and arranged obliquely upstream of the measuring unit 35a of the potential sensor 35 so that the light of the LED lamp 56 does not leak. Further, the light shielding plate 57 is also adapted to achieve the above object. FIG. 4 shows FIG.
FIG. In this figure, it can be seen that the LED lamp 56 emits light only on the upstream side of the contact roller 52.

Next, the measurement program (operation) of the above-mentioned scanning potential sensor unit 30 will be described with reference to the flowchart of FIG.

First, the measurement by the scanning potential sensor unit 30 is started immediately after the power of the apparatus main body 1 is turned on, when the main apparatus 1 is temporarily stopped, or after a predetermined use time (PO). The photosensitive drum 2 is rotationally driven, and the original illumination lamp 22 and other high-voltage power supplies around the photosensitive drum 2 are all turned off (P1). Even if the document illumination lamp 22 is off, the photosensitive drum 2 may be exposed by stray light or the like. Therefore, the document illumination lamp 22 or the like may be moved to a predetermined position without stray light.
Alternatively, a solid black portion on the standard density plate 29 (between AB in FIG. 2)
May be projected.

Then, the scanning carriage 31 of the scanning type potential sensor unit 30 which was previously in the photosensitive drum non-effective image area is moved to the effective image area (P2). The LED lamp 56 is turned on at this point. Then, a voltage is applied to the primary charger 5 (P3), and the measurement loop (S0
~ P9) is performed. First, the sensor measurement subroutine (S0) shown in FIG. 6 is executed. This is the potential sensor 35
Is measured and stored (S1), scanning movement for one sensor pitch is performed (S2), and this is executed up to the image end of the effective image area of the photosensitive drum 2 (S1 to S3). However, the measurement may be performed during the scanning movement or may be performed at the time of the stop. Then, in this case, since the original illumination lamp 22 is turned off or illuminates the black portion, the potential of the black portion is checked over the generatrix direction of the surface of the photosensitive drum 2 (P4). This checking method compares the maximum amplitude with respect to a variation in potential distribution with a predetermined value. if,
If there is an abnormal value (P5), a warning to that effect is displayed to the user (P6), and the interruption process (P7) is executed. Note that the interruption process is to stop the device or the like after executing P20 described later.

If there is no abnormal value, it is determined whether or not the bias voltage of the primary charger 5 is adjusted in consideration of the average value of the measured potential distribution and the defects of the maximum value and the minimum value. (P8). If the bias voltage should be changed, after changing (P9), the process jumps to the sensor measurement subroutine again.

Subsequently, the original illumination lamp 22 is turned on to illuminate the white solid portion (between BC in FIG. 2) on the standard density plate 29 (P10). In this way, the entire surface of the photosensitive drum 2 is exposed to white, and the sensor measurement subroutine (S0) is executed to measure the white portion potential of the photosensitive drum 2 in the bus line direction. Then, the white area potential is checked for any abnormal values (P11). If there is an abnormal value (P12), a warning is displayed to the user (P1) as in Kurobe.
3), interruption processing is executed (P14). If there is an excess or deficiency in the white part potential, the lamp voltage of the document illumination lamp 22 may be changed and the white part potential measurement loop (S0 (from below P10) to P14) may be repeatedly executed.

Then, the original illumination lamp 22 illuminates the halftone portion (between CDs in FIG. 2) on the standard density plate 29 (P15). In this way, the entire surface of the photosensitive drum 2 is exposed with halftone, and the sensor measurement subroutine (S0) is executed to measure the halftone potential of the photosensitive drum 2 in the bus line direction. Then, the halftone potential is also checked for abnormal values (P16). If there is an abnormal value (P17), a warning is displayed to the user similarly to the black and white parts (P18), and the interruption process is executed (P1).
9). In the check of the halftone potential, it is empirically extremely rare that the abnormal potential occurs only in the halftone unless black and white abnormalities occur. Therefore, it is not always necessary to perform the measurement of the halftone potential. Also, in comparison with a predetermined abnormal value (P17), by setting the abnormal value more strictly, it is grasped as one parameter for measuring the deterioration of the device itself, and it is continuously used by the user without executing interruption processing. You may ask.

Finally, the voltage applied to the primary charger 5 is turned off.
Then, the original illumination lamp 22 is turned off and is moved to a predetermined position, and the scanning type potential sensor unit 3
The scanning carriage 31 of 0 is evacuated to the ineffective image area of the photosensitive drum 2 (P20), and the normal mode is restored.

As described above, the following effects can be brought out by moving the scanning carriage 31 over the effective image area while the contact roller 52 is in contact with the surface of the photosensitive drum 2. Become. That is, even when the scanning type electric potential sensor unit 30 moves, the contact roller 52 always abuts on the surface of the photosensitive drum 2 by the compression spring 36, whereby the surface of the photosensitive drum 2 and the electric potential sensor 3 are contacted.
The detection distance x between the measurement unit 35a and the measurement unit 35a of No. 5 is always kept constant. In FIG. 7A, as a conventional example,
The measurement result when there is no contact roller 52 and the scanning type electric potential sensor unit is supported only on the scanning rail of the apparatus main body 2 is shown. Next, FIG. 7B shows an example of measurement results when the present invention is adopted under the same conditions except for the scanning potential sensor unit. The horizontal axis represents the position of the photosensitive drum 2 in the generatrix direction, and the vertical axis represents the measured potential. In the figure, among the measurement results, only the black portion potential is shown.

Obviously, the results of FIG. 7 (a) and FIG. 7 (b) are different, and the measurement result in the upper right corner as in (a) does not occur in (b). When measured under the above conditions, the installation accuracy of the scanning potential sensor unit 30 is reflected as it is, so that (a) has an error. According to the present invention, the eccentricity of the photosensitive drum 2 is also
Highly accurate measurement is possible with very little influence. <Embodiment 2 of the First Invention> In Embodiment 1, the charge distribution was measured over the direction of the generatrix on the photosensitive drum 2. This is the photosensitive drum 2, the primary charger 5, the original illumination lamp 2
With respect to the optical system such as 2, the processes such as checking the direction of the generatrix in the direction of the bus and changing the state quantity of the above element, or warning / interrupting were performed.

On the other hand, in the present embodiment (Embodiment 2), a scanning density sensor unit 60 for measuring the density of the toner image visualized on the photosensitive drum 2 by the developing device 7 will be described.

FIG. 8 shows a scanning density sensor unit 60 arranged between the developing device 7 and the transfer / separation charging device 9. The basic configuration of the scanning sensor unit 60 is
Example 1 except that the sensor is a density sensor
Scanning potential sensor unit 30 (shown in FIGS. 3 and 4)
Is almost the same as. In FIG. 8, 61 is a contact roller, 6
2 is a roller support receiver, 63 is a sensor fixing base, and 65 is a reflection type density sensor having a light emitting portion and a light receiving portion. A rotary contact fur brush 66 is arranged for the purpose of scanning and moving on the photosensitive drum 2 on which the toner image is adhered, for the purpose of preventing fusion of scattered toner to the contact roller 61. This is because the contact roller 61 of this embodiment is more likely to be contaminated than the contact roller 52 of the first embodiment. Further, 67 is a compression spring, 69 is a scanning carriage, 70 is a scanning rail, 71 is a supporting base attached to the apparatus main body (not shown), 72 is a stepping motor, and 73 is a pinion.
5 is a rack. However, the scanning density sensor unit 60 does not require a discharge lamp and a light shielding plate.

Next, FIG. 9 shows a schematic flowchart of the measurement program (operation) of the above-mentioned scanning type density sensor unit 60, which will be described below.

First, the scanning density sensor unit 60 is executed alone, or the measurement by the scanning density sensor unit 60 is started after measuring the potential distribution described in the first embodiment (Q0). The photosensitive drum 2 is rotationally driven, the original illumination lamp 22 is turned on, and all other high-voltage power supplies around the photosensitive drum 2 are turned off (Q1).
Next, the scanning carriage 69 of the scanning type density sensor unit 60, which was in the photosensitive drum non-effective image area in advance, is moved to the effective image area (Q2). Then, a voltage is applied to the primary charger 5, the document illumination lamp 22 is moved to the white solid part (between BC in FIG. 2) of the standard density plate 29, and a developing bias is applied (Q3). Then, the measurement loop (S0-Q
Execute 7). First, the sensor measurement subroutine (S0) shown in FIG. 10 is executed. This is to measure and store the sensor (R1), perform scanning movement for one sensor pitch (R2), and execute this up to the image edge of the effective image area of the photosensitive drum 2 (R1 to R3). Of course, in the first embodiment, the measurement was performed by the potential sensor 35, but this time, the measurement is performed by the concentration sensor 65, and since the schematic flowchart is the same, S0 is executed. However, the measurement may be performed during the scanning movement, or may be performed when the measurement is stopped. In this case, the original illumination lamp 22
Illuminates the solid white portion, the density of the white portion is checked in the generatrix direction of the photosensitive drum 2 (Q4). This checking method aims to detect defective cleaning of the photosensitive drum 2 by comparing it with a predetermined value. If there is an abnormal value (Q5), a warning to this effect is displayed to the user (Q6), and the interruption process (Q7) is executed. Note that the interruption process is, after executing Q18 described later,
To stop the device.

If there is no abnormal value, the document illumination lamp 22 is placed on the black chart portion (see FIG. 2) on the standard density plate 29.
Between the EFs) (Q8). The black chart portion has a band-shaped black portion, and the original illumination lamp 22 moves at a low speed between the EFs, so that a spiral toner image can be formed on the photosensitive drum 2. In this way, an excessive toner image does not adhere to the photosensitive drum 2 and the toner consumption amount can be reduced, and if the density sensor 65 is scanned and moved in synchronization with the low speed movement of the document illumination lamp 22, Toner can be brought into contact with the photosensitive drum 2 without adhering to the roller 61. Then, the sensor measurement subroutine 2 (R0) shown in FIG. 10 is executed to measure the black portion density of the photosensitive drum 2 in the generatrix direction. This performs measurement and storage (R1) of the sensor and scanning movement for one sensor pitch (R2), and further causes the original illumination lamp 22 to move to the scanning carriage 6.
It is slightly moved in synchronism with 9 (R3), and these are executed up to the image end of the effective image area of the photosensitive drum 2 (R1 to R4). Then, it is checked whether there is an abnormal value in the black portion density (Q9). If there is an abnormal value (Q10), a warning is displayed to the user (Q11), and the interruption process is executed (Q12).

Then, the original illumination lamp 22 illuminates the halftone chart portion (between DEs in FIG. 2) on the standard density plate 29 (Q13). Similarly to the black chart portion, the halftone chart portion also synchronizes the movement of the document illumination lamp 22 with the scanning movement of the scanning density sensor unit 60 (R0). Then, the halftone potential is also checked for abnormal values (Q14). If there is an abnormal value (Q15), a warning is displayed to the user similarly to the black and white parts (Q16), and the interruption process is executed (Q17). In this halftone density check, it is empirically extremely rare that abnormal density occurs only in halftone unless black and white abnormalities occur. Therefore, it is not always necessary to perform this halftone density measurement. In addition, in comparison with a predetermined abnormal value (Q15), the abnormal value is set to a stricter level to measure the deterioration of the device itself.
Grasped as one parameter, without executing interruption processing,
The user may subsequently use it.

Finally, the voltage applied to the primary charger 5 is turned off.
Then, the original illumination lamp 22 is turned off, and the scanning illumination density sensor unit 60 is moved to a predetermined position.
The scanning carriage 69 is evacuated to the ineffective image area of the photosensitive drum 2 (Q18), and the normal mode is restored.

In this way, the contact roller 6 with the photosensitive drum 2 is
By scanning and moving 1 over the effective image area of the photosensitive drum 2, the measurement accuracy is dramatically improved as in the first embodiment.

The scanning type density sensor 65 mounted in the present embodiment is installed not only upstream of the transfer separation charger 9 but also upstream of the cleaning device 10 so that the transfer efficiency is in the direction of the generatrix of the photosensitive drum 2. It is also possible to measure, and if the transfer to the transfer paper P is not executed, the scanning type density sensor 6 arranged upstream of the transfer separation charger 9 described in this embodiment.
5, it is possible to have the same performance. Alternatively, if it is arranged downstream of the cleaning device 10, it is possible to detect the cleaning performance. If the cleaning device 10 is provided with a release mechanism, it is also arranged upstream of the transfer separation charger 9 described in this embodiment. It has the same performance as the scanning density sensor 65.

Further, if the standard density plate 29 provided with the belt-shaped chart in this embodiment is used, it can be applied to the scanning type potential sensor 35 in the embodiment 1, and the contact roller 61 can be used.
Since only a low potential is constantly applied between the photosensitive drum 2 and the photosensitive drum 2, the static elimination LED lamp 56 becomes unnecessary.

In addition, the scanning type density sensor 6 of this embodiment
5 and the scanning-type potential sensor 35 described in the first embodiment can be driven in synchronization with each other, and the measurement time can be shortened.

Furthermore, the present invention can be applied not only to an image forming apparatus using an analog type electrophotographic technique, but also to an image forming apparatus equipped with a digital type exposure system having a laser, an LED or the like as a light source. In this case, the standard density plate 29
Not only is it possible to expose a predetermined amount of light without using it, but it is also possible to feed back to the repairing means such as adjusting the amount of exposure light by utilizing the distribution of the potential and the density that are accurately detected. <Third Embodiment of First Invention> In the first and second embodiments, the cylindrical photosensitive drum 2 is used as the photosensitive member. In the present embodiment (Embodiment 3), the scanning type sensor unit having a contact roller is used as a belt photosensitive member (photosensitive belt) 1.
No. 00 is applicable. Figure 11
FIG. 1 shows a schematic configuration diagram of an image forming apparatus using the photosensitive belt 100. As in FIG. 1, the static eliminator 3, the primary charger 5, the developing device 7, and the cleaning device 10 are arranged around the photosensitive belt 100. The transport system from the paper feed deck 11 to the paper discharge tray 20 and the optical system from the document illumination lamp 22 to the projection mirror 27 basically have the same configurations as those in the first and second embodiments.

Further, the scanning type potential sensor unit 30 and the scanning type density sensor unit 60 according to the first aspect of the invention are in contact with the photosensitive belt 100 via the respective contact rollers.

In this embodiment, in order to maintain the posture of the photosensitive belt 100 so that the posture of the photosensitive belt 100 does not collapse when the contact roller comes into contact with the photosensitive belt 100, from the rear surface of the photosensitive belt 100 to the rear surface side of the contact portion. Roller (base member) 80
Are arranged. This is provided in order to prevent the belt-specific development such as bending and twisting of the photosensitive belt 100 itself. As shown in the figure, the roller 80 may also serve as the belt supporting roller 90. Further, like the roller 80, two rollers may be disposed in contact with the contact rollers of the scanning sensor. Further, instead of the roller 80, a plate having a low coefficient of friction may be brought into contact with the back surface of the belt. <Embodiment 1 of the Second Invention> FIG. 12 schematically shows the configuration of an image forming apparatus showing an embodiment of the second invention. This image forming apparatus, which uses a common electrophotographic technique in a copying machine, a laser beam printer, a FAX, a printing machine, etc., includes an apparatus main body 1 and a photosensitive drum (photoreceptor) rotatably supported by the apparatus main body 1 in the direction of arrow R1. ) 2.

Around the photosensitive drum 2, a primary charger (charging device) 5 for uniformly charging the photosensitive drum 2 in order along the rotation direction thereof, and the photosensitive drum 2 are exposed to form an electrostatic latent image. Exposure unit 6 for forming, developing device (developing device) 7 for forming a toner image by adhering toner to an electrostatic latent image, transfer separation charging device (transfer device) 9 for transferring toner to transfer material P, photosensitive drum 2 Cleaning device 1 for removing excess toner above
0, a static eliminator 3 for eliminating static on the photosensitive drum 2 is arranged. The toner image charged and developed on the photosensitive drum 2 is fed from the paper feed deck 11 to the paper feed roller 12 and the transport roller 1.
On the transfer material P supplied to the photosensitive drum 2 via
It is transferred by the transfer separation charger 9. The transfer material P onto which the toner image has been transferred is conveyed by the conveyor belt 16, and after the toner image is fixed by the fixing device 17, the transfer material P is ejected onto the paper ejection tray 20 via the paper ejection roller 19. Also,
As an auxiliary component, a hopper 7a for replenishing the developing device 7 with toner is arranged immediately above the developing device 7, and below the cleaning device 10, from the photosensitive drum 2 to the transfer material P.
A separation claw 14 for mechanically separating the above is arranged such that the tip end thereof is close to the surface of the photosensitive drum 2.

On the other hand, the document illumination lamp 22 and the reflector 23 illuminate the document on the platen glass 21. The reflected light corresponding to the original image is reflected by the reflecting mirrors 25a and 25a.
b, 25c, and the scaling lens 26 and the projection mirror 2
The surface of the photosensitive drum 2 is exposed from the image exposure port 28 via the image exposure port 7.

Further, the standard density plate 29 is the platen glass 2
The document illuminating lamp 22 and the like can be moved so as to be installed near 1 so that an arbitrary amount of light can be exposed on the photosensitive drum 2 at the time of measuring the potential and the density. FIG. 13 shows a schematic diagram of the standard density plate 29. A halftone portion is shown between AB and a white background portion is shown between BC, and the respective light amounts are uniformly projected onto the photosensitive drum 2.

Then, as a means for realizing the image correction according to the present invention, as shown in FIG.
A scanning-type potential sensor unit 110 that measures the surface potential is arranged downstream of the image exposure port 28 in the rotation direction of the photosensitive drum 2 (direction of arrow R1) along the generatrix direction of the surface. This scanning potential sensor unit 110
14, the potential sensor 111 is attached to the scanning carriage 112, and scans on the scanning rail 113 in the arrow K1 direction (the generatrix direction of the surface of the photosensitive drum 2) over the effective image area 320 mm. The scanning method is the rack 115 fixed to the apparatus main body 1 and the stepping motor 116 and the pinion 11 mounted on the scanning carriage 112.
7 is used to control from the outside. And in order to improve not only the control of software but the operation reliability,
Limit switches 119 (the one on the far side is not shown) are arranged at both ends of the scanning rail 113 as safety switches for scanning drive control. In this embodiment, since the effective image area on the photosensitive drum 2 is read at 1 mm intervals in order to correct the density unevenness in the surface generatrix direction of the photosensitive drum 2, the mechanical sliding portions such as the scanning rail 113 and the gear are not read. It is installed and driven accurately. Further, when positioning is performed during scanning measurement, the initial position can be confirmed by calculating from the number of steps of the stepping motor 116 and resetting the limit switch 119.

The control unit 120 that scans and drives these sensors and executes measurement is in the apparatus main body 1 and controls according to the operation routine of this embodiment. Further, a microprocessor, a RAM, a ROM, an I / O interface and the like (not shown) are arranged inside the control unit 120, and operate as a storage unit or a calculation unit that stores the measured value.

By the way, as shown in FIG. 15, a scanning density sensor unit 130 may be provided as a detecting means for detecting the state of the surface of the photosensitive drum 2, instead of the scanning potential sensor unit 110 described above. . This is to measure the toner density on the photosensitive drum 2 after development in the rotation direction of the photosensitive drum 2 to grasp the deterioration state of the primary charger 5, the original illumination lamp 22, the developing device 7, and the like. Then, the configuration of the scanning density sensor unit 130 having a function of checking the visualization process including development is as follows.
The configuration is almost the same as that of the scanning potential sensor unit 110,
A concentration sensor (not shown) may be arranged instead of the potential sensor 111. The scanning potential sensor unit 110
By providing both the scanning density sensor unit 130 and the scanning density sensor unit 130, more accurate adjustment can be performed. In addition to the configuration shown in FIG. 15, the scanning density sensor unit 130 can also be configured to perform scanning measurement after transfer separation or on the transfer material P, and in these cases, similar effects can be obtained.

FIG. 16 shows the respective state quantities of the scanning potential sensor unit 110 shown in FIG. 14, the scanning density sensor unit 130 shown in FIG. 15, or a sensor (not shown) for measuring the toner density on the transfer material. It is a dimensionless, partial graph of the output example. The actual output value is represented by a charging potential (unit: volt) in the case of potential, and is represented by converting the reflected light quantity into a dimensionless density value in the case of density. This output value is defined as Xi as data at the measurement position. As described above, the effective image area of the photosensitive drum 2 is 1 m.
Since it is divided at m intervals, i takes a value from 0 to 320. The horizontal axis represents the position of the surface of the photosensitive drum 2 in the generatrix direction (the axial position), and the vertical axis represents the sensor output measurement value. Then, the ideal output value Xt and the average output value Xa
ve is represented by a one-dot chain line and a dotted line, respectively. Also shown are the output value Xa at the arbitrary point a and the value Xb at the arbitrary point b which is the intersection of the sensor output measurement value Xi and the output average value Xave.

In order to output a proper image, the average output value Xave must be set to the ideal output value Xt. However, in the conventional technique, a large amount of time is spent because the average output value Xave is used to repeatedly measure and adjust after changing the process condition.

Therefore, in the second invention, the adjustment time is greatly shortened by using a single measurement result Xi so as to obtain an appropriate output.

FIG. 17 shows a main operation flowchart for measuring the scanning potential sensor unit 110 used in this embodiment and adjusting the process state quantity according to the measurement result.

First, after the original illumination lamp 22 is turned off, a voltage is applied to the primary charger 5 to form a fully charged potential (hereinafter referred to as "dark portion potential") on the photosensitive drum 2 (m1). . Then, the potential of the photosensitive drum 2 is measured in the generatrix direction of the surface of the photosensitive drum 2 (m2), the dark part potential is also checked in the generatrix direction (m3), and the voltage applied to the primary charger 5 is adjusted to adjust the dark part potential. Is an appropriate value (m
4).

Next, the original illuminating lamp 22 is turned on to illuminate the halftone portion (between AB in FIG. 13) of the standard density plate 29 (m5), and the potential of the photosensitive drum 2 is set to the potential in the intermediate light amount exposure state ( Hereinafter referred to as "halftone potential"). Then, the potential of the photosensitive drum 2 is measured in the generatrix direction of the surface of the photosensitive drum 2 (m6), the halftone potential is also checked in the generatrix direction (m7), and the halftone potential is adjusted (m8). In addition, without a halftone part,
Even with a standard density plate having only a white background, the original illumination lamp 2
A similar effect can be obtained by lighting 2 at an intermediate voltage. On the contrary, with respect to the dark part potential, the aforementioned effect can be expected by providing the standard density plate having the black background part.

Subsequently, the original illumination lamp 22 is moved to a white background portion (between BC in FIG. 13) of the standard density plate 29 to illuminate it (m9), and the potential of the photosensitive drum 2 is set to a potential in a completely exposed state (hereinafter referred to as "brightness"). It is called "part potential"). Then, similarly to the above, the electric potential of the photosensitive drum 2 is measured in the generatrix direction of the surface of the photosensitive drum 2 (m10), and the light portion potential is also checked in the generatrix direction (m11). However, when the measurements are performed in the order described above, no special process conditions at the bright potential need to be adjusted when using analog electrophotography. Therefore, instead of measuring / adjusting the halftone potential, it is also possible to measure / adjust the bright portion potential and then measure the halftone potential. Also, in the case of a device that uses digital electrophotographic technology by exposing a laser or LED, the gain and offset of the exposure intensity of the light emitter can be adjusted or the desired emission intensity can be adjusted without distinction between the halftone potential and the bright part potential. It is possible to make adjustments such as rewriting the conversion table for obtaining

FIG. 18 is a flowchart showing the operation of sensor scanning movement and measurement common to the electric potential and the concentration. First, the scanning sensor is moved to either the front or the back (s1). At this time, by recording the number of pulses of the signal output of the stepping motor 116, if the limit switches 119 provided at the front and the back are not turned off even if the number of pulses exceeds the arbitrary number (s2), the limit switch 119 is abnormal. , Interrupt the measurement, warn or contact the user or service person, and have an instruction (s3). If the limit switch 119 is turned off (s
4) Since the current time is the end of the effective image area, the stepping motor 116 is stopped.

Next, a predetermined number of pulses are input to the stepping motor 116 to scan and move by an arbitrary distance (s
5). This distance is preferably about the same as the detection range in the sensor scanning direction, and is preferably 0.1 to 10 mm. In this embodiment, it is 1 mm as described above. After that, a subroutine for sensor measurement is executed (s6), and the measurement result is sent to the control unit 12
It is stored in the memory within 0 (s7). At this time, by storing the total number of pulses transmitted to the stepping motor 116, the current position is grasped, this position is represented by the subscript of i, and is recorded as the measurement result Xi. Then, steps s5 to s7 are repeated until the scanning movement reaches the total number of pulses to be moved by the effective image area of the photosensitive drum 2. When the movement of the effective image area is completed (s8), the present subroutine is ended and the operation flow chart of FIG. 17, which is the main operation routine, is returned to. In addition, even if the total number of pulses is not reached, the limit switch 119 is
If it is turned off (s9), stepping motor 11
6 and the limit switch 119 are abnormal, and the measurement is interrupted similarly to s3 (s10).

On the other hand, FIG. 19 shows an operation flowchart of the measurement subroutine shared by the potential and concentration sensors. Since the shortest time required for measurement of the sensor is a predetermined time, a minute time timer is provided (ss2) after the measurement result is input from the sensor (ss1). Then, this is measured a predetermined number of times in the rotation direction of the photosensitive drum 2 (ss3). this is,
It is executed a plurality of times to confirm whether there is an abnormal value in the measurement result in the rotation direction of the photosensitive drum 2 (ss4). If there is an abnormal value, a warning is given as a potential or density unevenness in the direction of rotation of the photosensitive drum 2, and the operation is interrupted (ss5). It should be noted that whether or not there is an abnormal value is determined by comparing it with a predetermined upper limit value and a predetermined lower limit value and determining whether it is the upper limit value or more or the lower limit value or less. The upper limit value and the lower limit value in the measurement result are any of a dark part potential, a halftone potential, and a light part potential when the measurement target is a potential. In the case of the density, a toner density value around which the measurement resolution of the sensor is high is used. If there is no abnormal value in the measured values, the average of the output values measured multiple times in the rotation direction of the photosensitive drum 2 is calculated (ss
6) Then, this subroutine is finished, and the routine returns to the routine for scanning movement and measurement of the sensor shown in FIG. A plurality of measured average values in the rotation direction of the photosensitive drum 2 obtained here are defined as Xi by adding a position subscript i.

Further, FIG. 20 shows an operation flowchart common to the check of the potential and the concentration in the subroutines for checking the respective potentials shown by m3, m7 and m11 in FIG. This check is a subroutine for investigating the sensor output measurement value Xi in the generatrix direction of the surface of the photosensitive drum 2. First, the maximum value and the minimum value of the sensor output measurement value Xi are calculated (c1). It is difficult to make appropriate even if the difference between the maximum value and the minimum value is within a predetermined allowable range (c2), and if the difference is outside the range, even if the adjustment amount of all areas is adjusted. , Warn or contact the user or service person and have instructions (c
3). For example, the maximum value of the dark potential on the photosensitive drum 2 is 5
00V, minimum value is 300V, proper value is 400V
In the case of, the difference between the maximum value and the minimum value is 200V, and the fluctuation is too large for 400V to be adjusted. Therefore, even if the potential is adjusted over the entire area of the photosensitive drum 2, the difference between the maximum value and the minimum value of the potential is not improved so much. That is, in such a case, it is often a fatal failure, and another repair is required, so the above interruption is executed.

Subsequently, the average value of all the areas of the surface of the photosensitive drum 2 in the generatrix direction is calculated (c4). The apparatus main body 1 cannot change the adjustment amount infinitely, but only within a limited range. Therefore, when the adjustment amount itself is the maximum value or the minimum value, that is, the extreme value, the adjustment cannot be performed any more. That is, when the adjustment amount is the extreme value and is far away from the average value and the predetermined value (c5), the adjustment is not performed like c3, and the process is interrupted (c6).

Then, the photosensitive drum 2 of the sensor output measurement value
The inclination of the surface in the generatrix direction is calculated (c7). In this embodiment, the least squares method is used. If this inclination is within a predetermined allowable range, it is compared (c8).
Similar to c3, the adjustment is not performed and the process is interrupted (c9).

In this way, the above-mentioned maximum value, minimum value, average value, and inclination are checked, and if adjustment is difficult, a warning or notification is sent to the user or service person to that effect, and an instruction is awaited. In the above check, in the case of the potential, the predetermined allowable values of the dark part potential, the halftone potential, and the bright part potential are stored, and the check judgment is performed by comparing them with each other. Also in the case of the density, it is possible to execute the check in the generatrix direction of the surface of the photosensitive drum 2 as described above in the same routine.

Next, FIG. 21 shows an operation flowchart for the subroutine for adjusting the dark part potential shown by m4 in FIG. The adjustment of the dark portion potential is to adjust the amount of current applied from the primary charger 5 to the photosensitive drum 2. In fact, the adjustment amount to be adjusted is the voltage applied to the primary charger 5 in this embodiment. Point to. First, the sensor output measurement value,
In this case, the difference between the average value Xave of the dark part potentials Xi and the ideal output value Xt is calculated, and this is defined as ΔX (p1). From this ΔX, a voltage correction amount for adjusting the current amount of the primary charger 5 is derived from a conversion table stored in advance, and this is set as Δα (p2). Then, by adding the correction amount Δα to the voltage applied to the primary charger 5 up to the previous time (p3), the primary current and thus the dark portion potential on the photosensitive drum 2 can be optimized. FIG. 22 is a graph showing a conversion table for determining the correction amount Δα of the primary charger applied voltage from ΔX. The horizontal axis shows the difference ΔX between the ideal output value Xt and the measured average value Xave, and the vertical axis shows the applied voltage correction amount Δα (unit: volt) of the primary charger 5. ΔX and Δα
This relationship is investigated and stored in advance in consideration of the charging characteristics of the photosensitive drum 2, the current-voltage characteristics of the primary charger 5, the environmental conditions, and the like. In addition, holding a plurality of conversion tables including the above characteristics also enables more detailed adjustment.

Next, FIG. 23 shows an operation flowchart for the subroutine for adjusting the halftone potential shown by m8 in FIG. In the halftone adjustment, the dark part potential of the photosensitive drum 2 is set to the original illumination lamp 22 or the standard density plate 2.
9 is the potential for reproducing the intermediate toner density,
In the case of the present embodiment, the adjustment amount that is actually adjusted is the voltage applied to the document illumination lamp 22. The outline of this flowchart performs the same operation as the adjustment of the dark part potential shown in FIG. That is, the difference between the sensor output measurement value, in this case the average value Xave of the halftone potential Xi, and the ideal output value Xt is calculated as ΔX (L1). From this ΔX, the correction amount of the voltage applied to the original illumination lamp 22 is derived from a conversion table stored in advance, and this is set as Δβ (L
2). Then, by adding the correction amount Δβ to the voltage applied to the document illumination lamp 22 up to the previous time (L3), the emission amount of the document illumination lamp, that is, the halftone potential on the photosensitive drum 2 can be optimized. As described above, the adjustment of the document illumination lamp 22 can be performed not only by using the halftone potential but also by using the bright portion potential. Figure 24
The conversion table for determining the correction amount Δβ of the original illumination lamp applied voltage from ΔX is shown in the form of a graph. As in FIG. 22, the horizontal axis represents the difference ΔX between the ideal output value Xt and the measured average value Xave.
And the correction amount Δβ on the vertical axis. The relationship between ΔX and Δβ is also preliminarily investigated and stored in consideration of the charging characteristic of the photosensitive drum 2, the voltage-light quantity characteristic of the document illumination lamp 22, the environmental condition, and the like. Of course, it is also useful to have a plurality of these conversion tables.

As described above, in this embodiment, the potential is measured in the direction of the generatrix on the surface of the photosensitive drum 2, and it is checked whether or not the measured value can be adjusted, and if possible, the adjustment is executed.

At this time, the output state quantity is optimized by preparing in advance a conversion table that directly associates the correction quantity with the measured average value. <Embodiment 2 of the second invention> In the above-described Embodiment 1, the potential is measured in the direction of the generatrix of the surface of the photosensitive drum 2, and the average value thereof and the conversion table of the output average value and the correction amount stored in advance are stored. I used the method of correcting it. On the other hand, in the present embodiment (Embodiment 2), the measurement result and the average value thereof in the busbar direction are used to perform remeasurement and recorrection at one arbitrary position in the busbar direction, and fine adjustment is performed for all areas in the busbar direction. is there. It should be noted that in the present embodiment, the scanning density sensor unit 13 is focused on the density after development on the photosensitive drum 2.
0 is used. The adjustment amount to be adjusted is the developing applied DC bias Vdc.

FIG. 25 shows a scanning density sensor unit 130.
The main operation flow chart for executing the measurement and the concentration adjustment according to the measurement result is shown. First, the original illumination lamp 22 is turned off, a voltage is applied to the primary charger 5, and an initial development bias is applied to create a dark toner concentration area on the photosensitive drum 2 (n1). Then, the scanning density sensor unit 130 measures the entire effective image area in the generatrix direction of the surface of the photosensitive drum 2 (n2). This measurement was performed using the scanning potential sensor unit 1 used in Example 1.
An operation similar to the control method of 10 is executed, and the sensor portion is replaced with a concentration sensor instead of the potential sensor. Similarly, the dark toner concentration check (n3) in the bus line direction also executes the same routine as in the case of the potential. Further, in this embodiment, the developing DC bias voltage V which is an important adjustment amount of the developing device 7 is obtained by using the obtained density measurement value.
dc is adjusted (n4). After that, the halftone density is visualized as in the case of the potential (n5), and this is measured (n6) and checked (n7). further,
A white background density is created (n8), measured (n9), and a check is performed (n10). The above halftone and white background density are only checked, but development conditions and the like may be determined using them. It should be noted that the white background density is an output value when toner is not originally attached to the photosensitive drum 2, and it means that there is no toner on the transfer material P, in other words, there is no fog.

FIG. 26 shows an operation flowchart for the subroutine for adjusting the developing DC bias voltage shown by n4 in FIG. In the development process,
The current DC bias voltage Vdc is an important adjustment amount that greatly affects the maximum and minimum density values, gradation, image quality, and the like with respect to the toner adhesion amount. Constant monitoring is needed to control, prevent and deal with.

First, the difference between the sensor output measurement value, in this case the average value Xave of the dark portion toner density Xi, and the ideal output value Xt is calculated, and this is designated as ΔX (d1). This ΔX
Then, a voltage for adjusting the developing DC bias voltage is derived from a conversion table stored in advance, and is set as Δγ (d2). Next, in this embodiment, the scanning density sensor unit 130 is moved to a predetermined arbitrary position a on the surface of the photosensitive drum 2 in the generatrix direction (d3). Then, the correction amount Δγ is added to the development DC bias voltage up to the previous time and the result is output (d
4).

Here, a point different from the collective correction by the conversion table used in the first embodiment is that the following control is executed. That is, after the correction, the measurement of the sensor is again performed only at the predetermined arbitrary position a, and the measurement result is set as X'a (d
5). Then, the minute correction (d7) and the measurement (d5) are repeated until X'a becomes (Xt + Xa-Xave) (d6). That is, a is set so that the value obtained by adding the difference between the initial output value Xa and the average value Xave becomes the ideal output value Xt.
The sensor output measurement value X'a at the point is adjusted. Thus, when X'a is adjusted, the average value Xave becomes substantially equal to the ideal value Xt. However, the correction and measurement may be repeated by a routine that is executed an arbitrary number of times.

In this way, in this embodiment, the whole area is measured in the generatrix direction of the surface of the photosensitive drum 2, and the average value and the measurement output result at the predetermined arbitrary position a are used to re-measure at the point a. Repeated measurement and readjustment. Therefore, the adjustment can be completed in a shorter time than the method in which the measurement and the adjustment are repeated several times in the generatrix direction of the surface of the photosensitive drum 2. <Third Embodiment of Second Invention> In the second embodiment, attention was paid to a predetermined arbitrary position on the surface of the photosensitive drum 2 in the generatrix direction, but in this embodiment, this position is significantly determined from the measurement result in the generatrix direction. There is. FIG. 27 shows an operation flowchart of a subroutine for adjusting the halftone potential of the photosensitive drum 2. First, the average value Xave of the sensor output measurement values Xi,
The difference from the ideal output value Xt is calculated, and this is taken as ΔX (v
1), the document illumination lamp 22 from the table for correcting ΔX
The correction amount Δβ for adjusting is derived (v2). Next, a point i for which Xi = Xave is searched from all measurement results (v
3). If there is one i point that is almost equal to Xave, (v
4) This point is stored as point b (v5). If a plurality of them exist, | Xi-Xi + 1 | + | Xi-1 -Xi
The point represented by | = minimum value, that is, the point having the smallest inclination near the point i where Xi = Xave is the point b (v
6). This is because at the time of adjustment, the smaller the inclination of measurement near point b, the more stable the result obtained.

After that, the scanning potential sensor unit 110
Is moved to the point b (v7). Next, the correction amount Δβ is added to the voltage applied to the original illumination lamp 22 up to the previous time and output (v8). Then, after the correction output, the sensor measurement is executed again only at the point b (v9), and the measurement result X '
Until b reaches the ideal output value Xt (v10), measurement and correction are repeated (v11). That is, since the point b is the average value of the entire area, the average value of the entire area is corrected to Xt by setting the output value at the point b to the ideal output value Xt.

In this way, the adjustment is shortened as in the second embodiment.

[0087]

As described above, the present invention has the following effects. <Effect of the First Invention> In the first invention, since the detection means for detecting the state of the surface of the photoconductor is provided with the spacer for keeping the detection distance between the surface of the photoconductor and the detector constant, Even when the detection unit moves along the generatrix of the surface of the photoconductor, the detection distance is accurately kept constant, and therefore the state of the surface of the photoconductor can be detected by the detection unit with high accuracy. <Effect of Second Invention> Further, a second invention is to adjust the state quantity based on a storage means that associates the measurement position of the detector on the photoconductor with the state quantity at the measurement position. Thus, for example, when determining a correction amount for adjustment, it is possible to make a determination while comparing the correction amount prepared in advance with a conversion table directly associated with it, so that the measurement time can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an outline of an image forming apparatus according to a first embodiment of the first invention.

FIG. 2 is a diagram showing a configuration of a standard density plate of Example 1 as well.

FIG. 3 is a sectional view showing the configuration of the scanning potential sensor unit of the first embodiment.

FIG. 4 is a view taken along the line A of FIG.

FIG. 5 is a flowchart showing the operation of the scanning potential sensor unit according to the first embodiment.

FIG. 6 is a flowchart showing a subroutine of the first embodiment.

FIG. 7A is a diagram showing a relationship between a position of a surface of a conventional photosensitive drum in a generatrix direction and a charging potential amount. FIG. 6B is a diagram showing the relationship between the position of the surface of the photosensitive drum in the busbar direction and the amount of charging potential in Example 1.

FIG. 8 is a sectional view showing a configuration of a scanning density sensor unit according to the second embodiment.

FIG. 9 is a flowchart showing the operation of the scanning density sensor unit of the second embodiment.

FIG. 10 is a flowchart showing a subroutine of the second embodiment.

FIG. 11 is a vertical sectional view showing the outline of an image forming apparatus according to a third embodiment of the first invention.

FIG. 12 is a vertical cross-sectional view showing the outline of the image forming apparatus according to the first embodiment of the second invention.

FIG. 13 is a diagram showing a configuration of a standard density plate of Example 1 similarly.

FIG. 14 is a perspective view showing a configuration of a scanning potential sensor unit according to the first embodiment as well.

FIG. 15 is a vertical sectional view showing the outline of the image forming apparatus according to the first embodiment.

FIG. 16 is a diagram showing a relationship between a position in the generatrix direction of the photosensitive drum of the first embodiment and a sensor output measurement value.

FIG. 17 is a main operation flowchart of the first embodiment of the present invention.

FIG. 18 is an operation flowchart of sensor scanning movement and measurement according to the first embodiment.

FIG. 19 is an operation flowchart of the measurement subroutine of the first embodiment.

FIG. 20 is an operation flowchart of potential and concentration check of the first embodiment.

FIG. 21 is an operation flowchart of dark part potential adjustment according to the first embodiment.

FIG. 22 is a correction table for dark area potential adjustment according to the first embodiment.

FIG. 23 is an operation flowchart of halftone potential adjustment according to the first embodiment.

FIG. 24 is a correction table for adjusting halftone according to the first embodiment.

FIG. 25 is a main operation flowchart of embodiment 2 of the second invention.

FIG. 26 is an operation flowchart of density adjustment on the photosensitive drum of the second embodiment.

FIG. 27 is an operation flowchart for halftone adjustment according to the third embodiment of the third invention.

[Explanation of symbols]

 2 Photoreceptor (Photosensitive Drum) 5 Charging Device (Primary Charger) 6 Exposure Device 7 Developing Device (Developer) 9 Transfer Device (Transfer Separating Charger) 30 Detecting Means (Scanning Potential Sensor Unit) 31 Scanning Cart 35 Detector (Potential sensor) 36 Biasing member (compression spring) 37 Driving means (stepping motor) 52 Spacer (contact roller) 55 Cleaning member (fur brush) 56 Static eliminator system (LED lamp) 60 Detection means (scanning density sensor unit) 65 Detector (Density Sensor) 80 Base Member (Roller) 100 Photosensitive Member (Photosensitive Belt) 110 Detecting Unit (Scanning Potential Sensor Unit) 111 Detector (Potential Sensor) 120 Storage Unit, Adjusting Unit, Computing Unit (Control Unit) 130 detection means (scanning density sensor unit) P transfer material x detection distance

Claims (15)

[Claims] 1. A charging device for uniformly charging a photoconductor, an exposure device for exposing the photoconductor to form an electrostatic latent image, and a toner image formed by adhering toner to the electrostatic latent image. In the image forming apparatus, a developing device, a transfer device that transfers the toner image onto a transfer material, and a detection unit that detects the state of the surface of the photoconductor, wherein the detection unit is a bus bar of the surface of the photoconductor. A scanning carriage that is movably disposed along the scanning carriage, a drive unit that moves the scanning carriage, and a detector that is mounted on the scanning carriage to detect the surface state of the photoconductor, and the scanning carriage. Includes a spacer that contacts the surface of the photoconductor to maintain a constant detection distance between the surface of the photoconductor and the detector, and a biasing member that presses the spacer against the surface of the photoconductor. A characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the scanning carriage has a cleaning member that cleans the spacer. 3. The detector is a potential sensor for detecting a potential on the surface of the photoconductor, the potential sensor being downstream of the charging device and upstream of the developing device in a rotation direction of the photoconductor. The image forming apparatus according to claim 1, wherein the image forming apparatus is arranged on the side. 4. The detector is a density sensor that detects the density of a toner image formed on the surface of the photoconductor, and the density sensor is downstream of the developing device in the rotation direction of the photoconductor. The image forming apparatus according to claim 1 or 2, wherein the image forming apparatus is arranged on the upstream side of the transfer device. 5. The static elimination system for changing the charge amount of the photoconductor is arranged on the upstream side of the contact area of the spacer with respect to the rotation direction of the photoconductor. 2. The image forming apparatus according to 2. 6. The photosensitive member is a photosensitive belt formed in a belt shape, and the spacer contacts the surface of the photosensitive belt and regulates the position of the photosensitive belt on the back surface side of the contact portion. The image forming apparatus according to claim 1 or 2, further comprising a base member. 7. A charging device for uniformly charging a photoconductor, an exposure device for exposing the photoconductor to form an electrostatic latent image, and a toner image formed by adhering toner to the electrostatic latent image. In the image forming apparatus, a developing device, a transfer device that transfers the toner image onto a transfer material, and a detection unit that detects the state of the surface of the photoconductor, wherein the detection unit is a bus bar of the surface of the photoconductor. A detector movably arranged along the direction, a positioning means for positioning the detector, a measurement position of the detector determined by the positioning means, and a detection result of the detector at the measurement position An image forming apparatus comprising: a storage unit that associates with the storage unit; and an adjustment unit that adjusts the state amount of the surface of the photoconductor in the generatrix direction based on the storage of the storage unit. 8. The image forming apparatus according to claim 7, further comprising a calculation unit that associates the state amount of the surface of the photoconductor with the adjustment amount of the adjustment unit. 9. The image forming apparatus according to claim 8, wherein the calculation unit calculates an average value, a maximum value, and an inclination of the state amount of the photoconductor in the generatrix direction. 10. The image forming apparatus according to claim 7, wherein the state quantity detected by the detection unit is a surface potential of the photoconductor. 11. The surface potential of the photoconductor is measured in at least one of a fully charged state, a charged state after intermediate light exposure, and a charged state after complete exposure. Image forming apparatus. 12. The image forming apparatus according to claim 7, wherein the state quantity detected by the detection unit is a toner density on the photoconductor or the transfer material. 13. The toner density is measured by at least one of a dark area toner density, an intermediate gradation toner density, and a light area toner density on the photoconductor or the transfer material. 12. The image forming apparatus according to item 12. 14. The state quantity adjusted by the adjusting means is an amount of charge on the photoconductor, an amount of exposure to the photoconductor, and an amount of developing toner adhered on the photoconductor or the transfer material. The image forming apparatus according to claim 7. 15. The adjusting means changes the adjustment amount so that the detector after the state amount measurement moved to a predetermined position obtains a predetermined state amount. The image forming apparatus according to any one of 1.