JP2004233436A - Electrophotographic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic recording device that adjusts and sets a voltage for a development roller according to the degree of property deterioration and prevents blur or omission of characters on a recording medium. <P>SOLUTION: A cumulative operation quantity computation means 7 measures and stores the quantity of cumulative operation of an electrostatic latent image carrier from the start of the use of fresh developer. A cumulative developer consumption quantity computation means 8 measures and stores the cumulative exposure area from the start of the use of the fresh developer. A development voltage control means 9 estimates the degree of property deterioration of the developer based upon the quantity of cumulative operation and the cumulative exposure area, and adjusts and sets the development voltage. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic recording device such as an electrophotographic printer.
[0002]
[Prior art]
2. Description of the Related Art In an electrophotographic recording apparatus such as an electrophotographic printer, the surface of a photosensitive drum is uniformly and uniformly negatively charged by a charging roller, and then an electrostatic latent image is written thereon by an LED head. A toner image is formed on the electrostatic latent image using a developing roller, a toner conveying roller, and the like. This toner image is transferred onto a recording medium by a transfer device. The transferred toner is fixed on a recording medium using a fixing device. Part of the toner remaining on the surface of the photosensitive drum after the fixing is removed by the cleaning roller. The remaining toner is carried to the developing roller while remaining on the surface of the photosensitive drum, and is collected by the developing roller. The collected toner is reused while being mixed with the toner in the developing device. Image reproduction is performed while continuously repeating the above process. A technique for effectively executing the toner reuse has also been disclosed (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-68905 (abstract)
[0004]
[Problems to be solved by the invention]
The toner recovered by the above process becomes fatigued by going around the process and no longer has the original charging characteristics. When a part of the toner whose characteristics have been deteriorated as described above is mixed, the charging characteristics of the entire toner in the developing device also deteriorates. Needless to say, the deterioration of the charging characteristics becomes more remarkable as the ratio of the collected toner in the toner in the developing device increases. Occasionally, characters on the recording medium may be blurred or even missing characters may occur.
An object of the present invention is to solve such a problem and to realize an electrophotographic recording device capable of reproducing a stable image.
[0005]
[Means for Solving the Problems]
The present invention employs the following configuration to solve the above points.
<Configuration 1>
An electrostatic latent image carrier on which an electrostatic latent image is formed by exposure by an exposure unit, a developer carrier for attaching a developer to the electrostatic latent image, and a developing voltage applied to the developer carrier A developing power source, a cumulative operation amount calculating means for counting and holding the cumulative operation amount of the electrostatic latent image carrier, a cumulative developer consumption calculating means for counting and holding the cumulative developer consumption, An electrophotographic recording apparatus comprising: a developing voltage control unit configured to set the developing voltage based on an operation amount and the accumulated developer consumption.
[0006]
<Configuration 2>
3. The electrophotographic recording apparatus according to claim 1, wherein the cumulative operation amount calculating means counts the cumulative operation amount based on the number of rotations of the electrostatic latent image carrier. .
[0007]
<Configuration 3>
In the electrophotographic recording apparatus according to Configuration 1, the cumulative developer consumption calculating means counts the cumulative developer consumption based on the number of exposure dots of the bitmap recording data. Recording device.
[0008]
<Configuration 4>
2. The electrophotographic recording apparatus according to Configuration 1, wherein the developing voltage control means sets the developing voltage for each predetermined number of prints.
[0009]
<Configuration 5>
The electrophotographic recording apparatus according to Configuration 1, further comprising a developer remaining amount detecting means for detecting the remaining amount of the developer, wherein after the remaining amount falls below a predetermined value, the remaining amount becomes a predetermined amount. An electrophotographic recording apparatus characterized by resetting the cumulative operation amount calculating means and the cumulative developer consumption amount calculating means when the value exceeds the value again.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
<Specific example 1>
Hereinafter, embodiments of the present invention will be described using specific examples.
In this specific example, the ratio of the collected toner amount among all the toner amounts in the developing device is obtained from the accumulated operation amount of the photosensitive drum and the accumulated exposure area of the number of exposure dots of the bitmap recording data. The degree of characteristic deterioration of the entire toner in the developing device is estimated from the ratio of the collected toner amount, and the voltage of the developing roller is adjusted according to the degree of characteristic deterioration, so that the characters on the recording medium are blurred or To prevent the occurrence of missing characters. In order to achieve such an object, the electrophotographic printer of this embodiment is configured as follows.
[0011]
FIG. 1 is a block diagram of the configuration of the first embodiment.
As shown in the figure, the configuration of the specific example 1 includes a photosensitive drum rotation number detection unit 1, an exposure dot number detection unit 2, a developing roller voltage control unit 3, a high voltage power supply 4, a storage unit 5, and a central processing unit 6.
An example in which the present invention is applied to an electrophotographic printer will be described. First, a configuration of an electrophotographic printer to which the present invention is applied and a control mechanism thereof will be described. Then, how the present invention is applied to such an electrophotographic printer will be described in detail.
[0012]
FIG. 2 is a block diagram of main components of the electrophotographic printer.
2, the electrophotographic printer to which the present invention is applied includes a photosensitive drum 11, a main motor 12, a motor driver 13, a drum counter 14, an LED exposure unit 15, an exposure control unit 16, a developing roller 17, a developing bias power source 18, a toner conveying roller 19, a sponge bias power source 20, a power control unit 21, an image signal processing unit 22, a dot counter 23, a control ROM 24, a data ROM 25, and a printer control unit. 26.
FIG. 3 is a sectional view of a main mechanism portion of the electrophotographic printer.
Main components of the electrophotographic printer to which the present invention is applied will be described mainly with reference to FIG. 3 and FIG. 2 together with its functions. 2 and 3 are denoted by the same reference numerals.
[0013]
The photosensitive drum 11 is a central part of an electrophotographic printer that forms a printing process by rotating in the direction of the arrow shown in the figure. It is a portion corresponding to the electrostatic latent image carrier in the claims. The printing process will be described below in the order of the arrows. The surface of the photosensitive drum 11 is usually covered with an insulator having high heat resistance such as a rubber material. The photoconductor drum 11 is rotated by the motor driver 13 (FIG. 2) driving the main motor 12 (FIG. 2) based on the control of the printer control unit 26 (FIG. 2). The rotation speed of the photosensitive drum 11 is measured by the drum counter 14 (FIG. 2), and the data is stored in the data ROM 25 (FIG. 2).
[0014]
The charging roller 32 is a portion that charges the surface of the photosensitive drum 11 to about −800 V as an example. A negative high voltage (not shown) is applied.
The LED exposure section 15 is a section that irradiates a light beam on the surface of the photosensitive drum 11 charged to about -800 V to form an electrostatic latent image of the image data 28 (FIG. 2). Usually, a light emitting element such as an LED array is used. This part is controlled by the exposure control unit 16 (FIG. 2).
[0015]
The image signal processing unit 22 (FIG. 2) is a part that converts the image data 28 (FIG. 2) into dot data. A light beam corresponding to the dot data is emitted from the LED exposure unit 15 to the surface of the photosensitive drum 11. The surface potential of the irradiated portion rises to near 0V. Thus, a potential change portion, that is, an electrostatic latent image is formed on the photosensitive drum 11.
[0016]
The dot counter 23 (FIG. 2) is a portion that counts the number of dots of original image data for one A4 sheet when the image signal processing unit 22 (FIG. 2) converts image data into dot data. The counted number of dots is stored in the data ROM 25 (FIG. 2).
The developing roller 17 is a part for developing the toner by adhering the toner 34 to the electrostatic latent image part of the photosensitive drum 11. The surface potential of the developing roller 17 is maintained at about -300 V by a developing bias power supply 18, for example. The developing roller 17 corresponds to a developer carrier in the claims.
[0017]
The toner transport roller 19 is a part that supplies toner to the developing roller 17. The surface potential of the toner conveying roller 19 is maintained at about -400 V by a sponge bias power supply 20 (FIG. 2), for example.
The power control unit 21 (FIG. 2) is a unit that sets and changes the surface potential of the developing roller 17 and the surface potential of the toner conveying roller 19 based on the control of the printer control unit 26 (FIG. 2).
[0018]
The developing blade 31 is a part that regulates the toner amount of the toner layer formed on the developing roller 17.
The transfer roller 37 is a part that transfers the toner image formed on the photosensitive drum 11 onto the paper 36. A high positive voltage is applied to transfer the negatively charged toner on the photosensitive drum 11 onto the paper 36.
[0019]
The transfer belt 35 is a portion that is driven by a transport roller (not shown) and transports the paper 36.
The cleaning device 33 is a part that removes the toner remaining on the photosensitive drum 11. The residual toner that is not removed here is carried to the developing roller 17 while being attached to the surface of the photosensitive drum 11, is collected by the developing roller 17, and is reused as it is.
The control ROM 24 (FIG. 2) is a section for storing programs, tables, and the like necessary for controlling the electrophotographic printer.
The printer control unit 26 is a CPU that controls the entire electrophotographic printer.
[0020]
The image signal processing unit 22 (FIG. 2), the dot counter 23 (FIG. 2), and the power supply control unit 21 (FIG. 2) may be individually configured as their own components. One function is included in the control program. If it is included in the control program, it is stored in the control ROM 24 in advance.
[0021]
Next, returning to FIG. 1 again, the configuration of the specific example 1 will be described.
As shown in FIG. 1, the functions of a photosensitive drum rotation number detection unit 1, an exposure dot number detection unit 2, a developing roller voltage control unit 3, a high voltage power supply 4, and a storage unit 5 are combined to calculate an accumulated operation amount. The means 7, the accumulated developer consumption calculating means 8, and the developing voltage control means 9 are included in an electrophotographic printer (one example) according to the present invention.
[0022]
The cumulative operation amount calculating means 7 is a means for counting and holding the cumulative operation amount of the electrostatic latent image carrier from the start of using the new developer. That is, it is means for accumulating and holding the developing operation amount since the toner 34 (FIG. 3) is newly replaced. The cumulative operation amount calculating means 7 is configured by integrating the photosensitive drum rotation number detecting section 1, the memory A, and the central processing section 6 as one body.
[0023]
Here, the photoconductor drum rotation speed detection unit 1 is the drum counter 14 (FIG. 2) that measures the rotation speed of the photoconductor drum 11 (FIG. 2). The rotation speed is cumulatively added by the central processing unit 6 (corresponding to the printer control unit 26 (FIG. 2)), and the value is stored in the memory A as the drum cumulative rotation speed. The memory A is a storage area secured in the data ROM 25 (FIG. 2).
[0024]
The cumulative developer consumption calculating means 8 counts and holds the cumulative exposure area from the start of use of the new developer. That is, it is a means for counting the number of dots of the electrostatic latent image formed on the surface of the photosensitive drum 11 (FIG. 2) from the time when the toner 34 (FIG. 3) is newly replaced, and accumulating and holding the number. The cumulative developer consumption calculating means 8 is configured by integrating the number of exposed dots detection unit 2, the memory B, and the central processing unit 6 into one.
[0025]
Here, the exposure dot number detection unit 2 is a part corresponding to the dot counter 23 (FIG. 2). When the image signal processing unit 22 (FIG. 2) converts the image data into dot data, one A4 sheet is used. This is a portion for counting the number of dots of the original document image data. The number of dots is the number of dots of the electrostatic latent image formed by irradiating the surface of the photosensitive drum 11 charged to about -800 V with the light beam by the LED exposure unit 15, that is, the exposure dot of the bitmap recording data. The result is equal to the number. The electrostatic latent image formed by the exposure is developed with toner corresponding to the dots by a developing roller. That is, the toner consumption can be estimated by counting the number of exposure dots.
[0026]
The number of exposure dots is cumulatively added by the central processing unit 6 (corresponding to the printer control unit 26 (FIG. 2)), and the value is stored in the memory B as the number of cumulative exposure dots. The memory B is a storage area secured in the data ROM 25 (FIG. 2).
[0027]
The developing voltage control means 9 is a means for estimating the degree of characteristic deterioration of the developer based on the cumulative operation amount and the cumulative exposure area, and adjusting the developing voltage by setting. That is, the degree of characteristic deterioration of the toner as a whole in the developing device into which the collected toner is mixed is determined by the cumulative number of drums of the photosensitive drum 11 (FIG. 2) and the cumulative number of exposure dots of the electrostatic latent image. And a means for setting the developing voltage by adding or subtracting it. The developing voltage control means 9 is configured integrally with the developing roller voltage control unit 3, the memory C, the high voltage power supply 4, and the central processing unit 6.
[0028]
Here, the developing roller voltage control unit 3 corresponds to the power supply control unit 21 (FIG. 2), and the surface potential of the developing roller 17 is controlled based on the control of the printer control unit 26 (FIG. 2) (corresponding to the central processing unit 6). And the surface potential of the toner transport roller 19, or any one of them. The high-voltage power supply 4 corresponds to a sponge bias power supply 20 for maintaining the surface potential of the toner conveying roller 19 (FIG. 2) and / or a developing bias power supply 18 for maintaining the surface potential of the developing roller 17. Here, only the developing bias power supply 18 will be described.
[0029]
The memory C is a storage area secured in the control ROM 24 (FIG. 2), and stores a developing roller voltage data table. An example of the developing roller voltage data table will be described.
FIG. 4 is a developing roller voltage data table.
The level of the characteristic deterioration degree (duty (%)) of the entire toner is determined in the left column of the table, and the developing roller voltage to be set according to the level is determined in the right column.
[0030]
Here, the content of the characteristic deterioration degree (duty (%)) will be described.
duty = A * (cumulative number of exposure dots) / (cumulative number of rotations of drum) (Equation 1)
Here, A is a constant.
This equation (1) represents the amount of toner actually used (the number of accumulated exposure dots) with respect to the total operation amount (the cumulative number of drum rotations) actually printed. Therefore, it is possible to estimate the amount of toner collected without being actually used from Equation (1). That is, it means that the smaller the (duty (%)), the larger the amount of toner that is not actually used and is collected.
[0031]
In other words, the smaller the duty (%), the more the properties of the toner are degraded, so that it is necessary to increase the developing roller voltage. According to the experiment performed by the inventor, L, M, and H in the right column of FIG. 4 indicate that the unexposed portion of the surface of the photosensitive drum 11 (FIG. 2) is -800 V, and the exposed portion is -800 V. For 50 V, optimal results were obtained by setting L = -300, VM = -350 V, and H = -400 V. However, since this result differs depending on the model of the electrophotographic printer, the potential of the surface of the photosensitive drum 11 (FIG. 2), and the like, it is a value that should be set by accumulating experimental data individually, and is limited to this example. Not something.
[0032]
In the above description, in calculating the characteristic deterioration degree (duty (%)), the number of rotations of the photosensitive drum 11 (FIG. 2) is used as the accumulated operation amount, but the present invention is not limited to this example. . That is, it may be calculated from the number of printed sheets, the executed number of jobs, and the like.
In the above description, the timing of calculating the characteristic deterioration degree (duty (%)) is not clarified. However, this timing may be a predetermined print amount elapsed time or may be each time a printing operation is started. May be.
It is to be noted that, when the use of a new developer in the claims is started, this includes not only the case where the toner in the developing device is updated to a new toner, but also the case where a new toner is added.
[0033]
<Effect of Specific Example 1>
As described above, the ratio of the collected toner is obtained from the accumulated amount of the operation of the photosensitive drum and the accumulated number of the exposure dots of the bitmap recording data from the time when the toner is newly added. Characteristic deterioration (duty) of the toner as a whole is estimated from the ratio, and the voltage on the developing roller is adjusted by setting the voltage of the developing roller in accordance with the characteristic deterioration. The effect is obtained that it can be prevented from being performed.
[0034]
<Specific example 2>
In the specific example 1, the reset of the memory A and the memory B at the time of updating to the new toner is not described. If this reset is left to the operator's effort, forgetting to reset cannot be ignored. Therefore, in this specific example, a toner remaining amount detection unit is further provided to detect when the toner is updated to new toner, and at the time of this update, the memory A and the memory B are automatically reset, and the reproduced image due to forgetting to reset is reproduced. To prevent quality deterioration. In order to achieve such an object, an electrophotographic printer (one example) of the second embodiment is configured as follows.
[0035]
FIG. 5 is a block diagram of the configuration of the second embodiment.
As shown in the drawing, the configuration of the specific example 2 includes a photosensitive drum rotation number detection unit 1, an exposure dot number detection unit 2, a developing roller voltage control unit 3, a high voltage power supply 4, a storage unit 5, a remaining toner amount detection unit 41, and a memory AB. A reset unit 42 and a central processing unit 46 are provided.
[0036]
Only differences from the first specific example will be described.
The remaining toner amount detection unit 41 is a part that constitutes a remaining developer amount detection unit that detects the remaining amount of the developer integrally with the central processing unit 46.
That is, during the printing process, the remaining toner amount detection unit 41 measures a cycle of a link rotating in a toner tank (not shown), and measures a remaining toner amount based on the length of the cycle.
[0037]
When the toner amount falls below the predetermined amount, a toner LOW signal is output from the remaining toner amount detection unit 41, and an alarm indicating that the toner amount is low is displayed on the operation panel via the central processing unit 46. The operator who sees this alarm will add toner. The alarm display is continuously displayed until the operator adds toner. When toner is added, the remaining toner amount detection unit 41 stops outputting the toner LOW signal. As a result, the alarm display is canceled.
[0038]
The memory AB reset unit 42 controls the cumulative operation amount (the cumulative number of rotations of the photosensitive drum) stored in the memory A and the cumulative exposure area (the number of exposure dots) stored in the memory B under the control of the central processing unit 46. Are reset (returned to 0).
[0039]
After receiving the toner LOW signal from the remaining toner amount detection unit 41, the central processing unit 46 updates the toner in the developing device to new toner when the toner LOW signal is stopped (including addition of new toner). ) And resetting by sending a reset signal to the memories A and B.
The other parts are completely the same as in the first embodiment, and the description is omitted.
[0040]
<Effect of Specific Example 2>
As described above, the electrophotographic printer of this specific example is provided with the developer remaining amount detecting means, so that when the toner is updated (including addition), the memories A and B are reset, and the developing voltage is changed based on the developing voltage. Since it is returned, an adverse effect such as excessive printing is eliminated, and an effect that a good reproduced image can be obtained is obtained.
[0041]
【The invention's effect】
As described above, the cumulative operation amount calculating means for counting and holding the cumulative operation amount of the electrostatic latent image carrier, the cumulative developer consumption calculating means for counting and holding the cumulative developer consumption, By including the developing voltage control means for setting the developing voltage based on the cumulative operation amount and the cumulative developer consumption, it is possible to prevent the characters on the recording medium from being blurred or missing characters. The effect is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of a configuration of a specific example 1.
FIG. 2 is a block diagram of main components of the electrophotographic printer.
FIG. 3 is a sectional view of a main mechanism of the electrophotographic printer.
FIG. 4 is a developing roller voltage data table.
FIG. 5 is a block diagram of a configuration of a specific example 2.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 photosensitive drum rotation number detection unit 2 exposure dot number detection unit 3 developing roller voltage control unit 4 high voltage power supply 5 storage unit 6 central processing unit 7 cumulative operation amount calculation unit 8 cumulative developer consumption amount calculation unit 9 development voltage control unit

Claims (5)

An electrostatic latent image carrier that is exposed by an exposure unit and on which an electrostatic latent image is formed;
A developer carrier for attaching a developer to the electrostatic latent image;
A developing power supply for applying a developing voltage to the developer carrier;
Cumulative operation amount calculating means for counting and holding the cumulative operation amount of the electrostatic latent image carrier,
Cumulative developer consumption calculating means for counting and holding the cumulative developer consumption,
An electrophotographic recording apparatus comprising: a developing voltage control unit configured to set the developing voltage based on the cumulative operation amount and the cumulative developer consumption. The electrophotographic recording apparatus according to claim 1,
The cumulative operation amount calculating means,
An electrophotographic recording apparatus, wherein the cumulative operation amount is counted based on the number of rotations of the electrostatic latent image carrier. The electrophotographic recording apparatus according to claim 1,
The cumulative developer consumption calculating means,
An electrophotographic recording apparatus, wherein the cumulative developer consumption is counted based on the number of exposure dots of bitmap recording data. The electrophotographic recording apparatus according to claim 1,
The developing voltage control means,
An electrophotographic recording apparatus, wherein the developing voltage is set for each predetermined number of prints. The electrophotographic recording apparatus according to claim 1,
The image forming apparatus further includes a developer remaining amount detecting unit configured to detect the remaining amount of the developer,
When the remaining amount exceeds a predetermined value again after the remaining amount falls below a predetermined value, the cumulative operation amount calculating means and the cumulative developer consumption amount calculating means are reset. Photo recorder.

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