JP2000038238A - Paper sheet conveying mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a conveying amount of recording paper in detection delay time of a paper sheet sensor accurately to obtain the length of recording paper correctly in a paper sheet conveying mechanism in which recording paper is conveyed intermittently. SOLUTION: The number of conveyance steps in paper sheet conveyance from the time when a tip of recording paper is detected by a paper sheet sensor (S2: YES) to the time when a rear end thereof is detected is counted by a counter (S3), and the number of conveyance steps in detection delay time of the paper sheet sensor is stored in a RAM at the same time. When the rear end of recording paper is detected (S5: YES), the number of conveyance steps stored in the RAM is subtracted from the number of conveyance steps by this counting to obtain a length of recording paper (S8). As a result, a detection error of the length of recording paper caused by detection delay time of the paper sheet sensor is compensated even in a system in which recording paper is conveyed intermittently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for an image recording apparatus such as a facsimile machine, a copying machine, a printer, etc.
The present invention relates to a paper transport mechanism for intermittently transporting recording paper, and more particularly, to a technique for detecting a recording paper length using a paper sensor.

[0002]

2. Description of the Related Art Conventionally, a recording apparatus having a recording head for performing recording in a predetermined line unit in a direction orthogonal to a recording paper transport direction has been provided, and the recording paper is transported intermittently. A paper transport mechanism having a function of detecting a length is known. In this paper transport mechanism, a paper sensor (registration sensor) for detecting a paper jam in the paper transport path is provided upstream of the recording head position. When the recording paper is transported, the paper sensor detects the paper. When the leading edge is detected, the number of transport steps of the paper transport mechanism is counted until the trailing edge is detected, and the length of the recording paper can be obtained based on the counted value. By determining the length of the recording paper in this manner, even when performing recording without a page concept on a recording medium, such as copying or receiving recording, a predetermined margin is taken at the end of the recording medium to guarantee the recording range. I keep the record inside.

[0003]

However, in the case where the paper sensor provided in the above-described conventional paper transport mechanism detects the presence or absence of the recording paper by a mechanical configuration, the recording is performed. When the sheet is conveyed to the detection position of the sensor, a certain detection delay time occurs until the detection signal is actually transmitted. Here, in an ink jet printer using a serial head in which a paper transport mechanism intermittently transports recording paper (for each recording line), the amount of recording paper transported within a certain time is not necessarily uniform. Therefore, the amount of recording paper transported during the detection delay time cannot be easily grasped. Therefore, the recording paper length obtained based on the counter value from when the leading edge detection signal of the recording paper is received to when the trailing edge signal is received may have an error. Since the position of the set and the position of the trailing end of the recording paper that is actually conveyed are different, when recording is performed on the recording paper, it is difficult to finish the recording accurately within the guaranteed recording range, There is a problem that the length of the margin on the paper varies.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. Even when recording paper is intermittently conveyed, the recording paper conveyance amount within the detection delay time of the paper sensor is accurately determined. It is another object of the present invention to provide a paper transport mechanism that can accurately detect the length of a recording paper, and can accurately perform recording within a guaranteed recording range.

[0005]

According to another aspect of the present invention, there is provided a recording apparatus having a recording device for performing recording in a predetermined line unit in a direction orthogonal to a recording paper transport direction. And a transporting means for intermittently transporting the recording paper, provided upstream of the recording means,
A sheet sensor for detecting a leading edge and a trailing edge of the recording sheet conveyed by the conveying means, wherein the trailing edge detection signal is obtained from the time when the leading edge detection signal of the recording sheet is obtained by the sheet sensor. A counter that counts the number of transport steps of the transport unit up to the point in time, and a transport step by the transport unit within the detection delay time of the paper sensor before the time when the trailing edge detection signal of the recording paper is obtained by the paper sensor. Storage means for counting and storing the number, and recording paper length detecting means for calculating the length of the recording paper by subtracting the number of transport steps stored in the storage means from the number of transport steps counted by the counter. It was done.

In the above arrangement, the counter counts the number of paper transport steps between the leading edge detection signal and the trailing edge detection signal of the recording paper by the paper sensor, and the paper sensor detects the trailing edge of the recording paper. The number of transport steps within the detection delay time is stored in the storage means,
The length of the recording paper is determined by subtracting the number of transport steps stored in the storage means from the number of transport steps counted by the counter by the recording paper length detecting means. As a result, even if the recording paper is intermittently conveyed, the detection error of the recording paper length due to the detection delay time of the paper sensor is corrected.

[0007] Further, the paper transport mechanism according to the second aspect of the present invention,
2. The paper transport mechanism according to claim 1, wherein the storage unit comprises:
At least the number of transport steps within a time corresponding to the delay time is stored in a plurality of areas in chronological order and stored in each area by an interrupt process at a predetermined interval shorter than the delay time. The number of transport steps is stored.

In the above configuration, the storage means stores the number of transport steps within the delay time by storing the number of transport steps at a predetermined interval shorter than the delay time in each of the plurality of areas of the storage means. Therefore, at the time when the trailing edge detection signal of the recording paper is detected by the paper sensor, the error between the number of transport steps within the delay time stored in the storage means and the actual number of transport steps within the delay time is determined by the predetermined value. It can be limited to the number of transport steps within the interval.

The paper transport mechanism according to claim 3 is
3. The paper transport mechanism according to claim 2, wherein the storage unit comprises:
The number of transport steps for the latest interrupt processing is newly stored in the first area, and the oldest number of transport steps stored in the last area is shifted out.
At least the number of transport steps corresponding to the delay time is stored.

In the above configuration, each time the number of transport steps of the latest interrupt processing is obtained, the number of transport steps and the oldest number of transport steps are rewritten. The number of transfer steps within the delay time can be stored.

The paper transport mechanism according to claim 4 is
In the paper transport mechanism according to any one of claims 1 to 3, when the trailing edge of the recording paper is not detected by the paper sensor when the counter value of the counter reaches a predetermined value, a paper jam of the recording paper. Is determined to have occurred.

In the above configuration, since the occurrence of a paper jam is determined based on the counter value of the counter, a paper sensor for detecting the length of the recording paper and a sensor for detecting the occurrence of the paper jam are provided. Can be used in combination.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a paper transport mechanism according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external view of a recording apparatus provided with a paper transport mechanism according to an embodiment of the present invention. The recording apparatus 1 has various functions such as a facsimile function, a printer function, a copy function, and a scanner function.

The main body of the recording apparatus 1 is formed in a box shape, and both left and right sides thereof are covered by side covers 2 and 3 which are cosmetic cases. These side covers 2, 3
Is attached to a body frame (not shown). An image reading unit 4 (see FIG. 2) for reading an image of a document (not shown) is provided between the side covers 2 and 3 so as to be rotatable around a shaft 22 (see FIG. 2) with respect to the apparatus main body. I have. In addition, an ink jet recording unit 5 (recording unit,
(See FIG. 2), and the image reading unit 4 is arranged so as to cover a part of the recording unit 5 so as to be overlapped vertically, thereby saving space. At the rear of the apparatus main body, a recording paper cassette 6 for stacking and storing recording paper is mounted.

On the upper surface of the image reading unit 4, a key operation unit 7a and a display unit 7 such as an LCD display are provided.
The operation panel 7 having the letter “b” is arranged. At the rear of the image reading unit 4, there is provided a document placing section 9 on which a facsimile document to be transmitted to a partner facsimile apparatus during the facsimile function and a copy document to be copied during the copy function can be stacked. A document discharge unit 10 is provided on the front surface of the apparatus main body, and a document discharge tray 12 is mounted on the document discharge unit 10. A recording paper discharge unit 13 is provided below the document discharge unit 10, and a recording paper discharge tray 14 is mounted on the recording paper discharge unit 13.

FIG. 2 is a sectional view of the recording apparatus 1.
Each component will be described. The document reading unit 4 includes a scanner unit 15, and the scanner unit 15 has an image sensor 17 made of a CCD or the like facing a transport path 16 that transports the read document placed on the document placing unit 9.
A separation roller 1 that separates and feeds a document is provided in the conveyance path 16.
8, a paper feed roller pair 19 for transporting the document, a paper discharge roller pair 20 for discharging the read document to the document discharge unit 10, and the like. The recording unit 5 includes an ink jet recording head 25 that ejects ink droplets. The recording head 25 is mounted on a carriage 26 together with an ink cartridge 27. The carriage 26 is guided by a carriage shaft 28 and is scanned and moved by a driving mechanism (not shown) including a carriage motor 45 during a printing operation.

In the recording paper cassette 6, the set recording paper P is transported by a paper feed roller 34 to a transport path 35.
Separated and fed. A paper feed roller (transporting means) 36, a platen 37 facing the recording head 25, a paper discharge roller 38 for discharging the recording paper P after recording to the recording paper discharge unit 13, and the like are arranged facing the transport passage 35. . A drive mechanism including a transport unit 47 for driving various rollers and the like is not shown. Further, a paper sensor 40 for detecting the leading end and the trailing end of the recording paper P being transported is provided upstream of the recording head 25 and near the paper feed roller 36. The paper sensor 40 detects the leading end of the recording paper P when the switch is turned on when the recording paper P comes into contact with the conveyed recording paper P, and is turned off when it is not contacted. This is a contact-type sensor that is mechanically configured so that the rear end can be detected. From the paper sensor 40, a CP which controls the operation of the entire apparatus is provided.
The control unit 41 (see FIG. 3) composed of U transmits a leading edge detection signal and a trailing edge detection signal of the recording paper P.

FIG. 3 is a schematic block diagram of the recording apparatus 1. The recording apparatus 1 is provided with a control section (recording sheet length detecting means) 41 for controlling the entire recording apparatus 1. The control section 41 includes an operation program for the entire apparatus and recording sheet length by a sheet transport mechanism. A ROM 42 storing a detection program and the like is connected, and a RAM (storage means) 43 for storing image data and the like used for recording.
Is connected. The control unit 41 includes a recording head driving unit 44 for driving the recording head 25, a carriage motor 45 including a step motor for operating and moving the recording head 25 on the recording paper P, and recording by a user operation. The operation unit 7a of the operation panel 7 to which an operation start is instructed is connected.

The controller 41 is connected to a transport motor (transport means) 47 comprising a step motor, which is a driving source for the paper feed rollers 34 and 36 for transporting the recording paper P. The operation is controlled in accordance with the recording operation of the recording head 25. Further, a paper sensor 40 is connected to the control unit 41, and a leading edge detection signal and a trailing edge detection signal of the recording paper P are input from the paper sensor 40. The jam counter (counter) 48 counts the number of drive pulses of the transport motor 47 to measure the number of transport steps of the transport motor 47. The control unit 41 detects the leading edge of the recording paper P obtained from the paper sensor 40. The start and stop of counting are controlled in accordance with the signal and the rear end detection signal. As shown in FIG. 4, the RAM 43 stores a jam counter storage area 43a for sequentially storing the counter value of the jam counter 48 for a predetermined time (10 ms).
For each c), a correction buffer area 43b for correcting the length of the recording paper for storing the value counted by the jam counter 48 within the predetermined time, a control flag 43c indicating that a periodic interrupt process is to be performed, and a recording paper Error flag 4 indicating that a paper jam of P has been determined to have occurred
3d and the like are provided.

Next, detection of the recording paper length by the paper transport mechanism will be described. FIG. 5 is a flowchart showing the flow of processing when the recording paper length is detected, and FIG. 6 is a diagram showing the use status of the recording paper length correction buffer. The detection of the length of the recording paper by the paper transport mechanism is based on the counter value of the jam counter 48 from the time when the leading edge detection signal of the recording paper P is obtained from the paper sensor 40 to the time when the trailing edge detection signal is obtained. From the time when the trailing edge detection signal is obtained from the recording paper conveyance amount.
This is performed by subtracting the recording paper transport amount within the time that is traced back by the detection delay time (here, 100 msec).

First, when the recording operation by the recording head 25 is started, the recording paper is fed from the recording paper cassette 6 to the recording section 5, and the jam counter 48 and the buffer flag are initialized accordingly. Is performed (S1). Then, the recording sheet P is transported to the position of the sheet sensor 40, and the leading end of the recording sheet P is detected, and the sheet sensor 40
Is turned on (S2: YES), the count of the number of drive pulses of the transport motor 47 by the jam counter 48 is started from that point, and the control flag 43
c is set (S3). This counter value is stored in RAM4
3 is stored in the jam counter storage area 43a, and is updated to a new value each time it is counted. After the count by the jam counter 48 is started, the counter value (the number of driving pulses) counted by the jam counter 48 within the predetermined time is corrected by the RAM 43 every predetermined time (here, 10 msec) by a periodic interrupt. A process of storing the data in the buffer area 43b for a fixed time is performed (S4). The measurement of the time of the interruption interval is performed by a timer 41a built in the control unit 41.

Here, the periodic interruption processing (S4) will be described. Each time a predetermined time elapses (every 10 msec elapses), the counter value counted by the jam counter 48 within the predetermined time is stored in the correction buffer area 4 of the RAM 43.
The counter value obtained by the process of storing the data in the buffer 3b is stored in the correction buffer area 43b for 100 msec, which is the detection delay time of the paper sensor 40. Therefore, in the correction buffer area 43b, the number of transport pulses within a time corresponding to the detection delay time, that is, the recording paper transport amount (LF amount) is stored in a time-series manner in a plurality of areas. The transport amount for a predetermined time is stored. Specifically, as shown in FIG.
In b, ten data indicating the recording paper transport amount (LF amount) every 10 msec elapse is stored.

When new data of the recording paper transport amount for 10 msec is obtained, the correction buffer area 43 has already been obtained.
The oldest data among the ten data stored in b is rewritten with newly obtained data. That is, every time the latest recording paper transport amount is obtained for each interruption interval, the latest transport amount is stored in the head area of the correction buffer area 43b, and the oldest transport data is shifted to the tail area. Be out. Therefore, if the sum of the ten data stored in the correction buffer area 43b is calculated, the detection delay time (100
The conveyance amount of the recording paper P conveyed during (msec) is obtained. Thus, even when the recording paper P is intermittently conveyed by the paper feed rollers 36 and 38, the recording paper P is stored in the correction buffer area 43b of the RAM 43 when the paper sensor 40 detects the rear end of the recording paper. The difference between the recording paper transport amount within the detection delay time and the actual recording paper transport amount can be kept within the range of the error of the recording paper transport amount in the interrupt processing interval (10 msec).

The count of the jam counter 48 started after the detection of the leading end of the recording sheet P is performed when the trailing end of the recording sheet P is detected by the sheet sensor 40 and the sheet sensor 40 is turned off. (S5: YES) The operation is stopped, the control flag 43c is turned off (S6), and the above-mentioned periodic interrupt processing is also terminated (S6).
7). Then, the recording paper length is calculated by subtracting the sum of the ten transport amounts stored in the correction buffer area 43b from the length of the recording paper P indicated by the counter value of the jam counter 48 at this time. (S8).
If the trailing end of the recording paper P is not detected by the paper sensor 40 when the count value of the jam counter 48 reaches a predetermined value (S9: YES), it is determined that a paper jam has occurred in the recording paper. Then, the error flag 43d is turned on in the RAM 43, and "paper jam" is displayed on the display section 7b (S10).

As described above, according to the sheet transport mechanism of the present embodiment, when the trailing end of the recording sheet P is detected by the sheet sensor 40, the recording obtained based on the count value of the jam counter 48 at that time. Since the recording paper length is calculated by subtracting the recording paper transport amount stored in the correction buffer area 43b, that is, the recording paper transport amount within the detection delay time of the paper sensor 48, from the length of the paper P. In addition, it is possible to correct a recording paper length detection error caused by the detection delay time of the paper sensor 48, and to obtain an accurate length of the recording paper P. The recording paper transport amount within the detection delay time of the paper sensor 48 stored in the correction buffer area 43b is rewritten to a new transport amount every 10 msec while the recording paper P is being transported. Even when the recording paper P is intermittently conveyed by 36, 38, etc., the recording paper conveyance amount within the detection delay time can be accurately obtained. As a result, at the time of recording, a margin as expected can be accurately provided at the end of the recording sheet, and the recording can be accurately contained within the range guaranteed by the recording apparatus.

The present invention is not limited to the configuration of the above embodiment, and various modifications are possible. For example, in the above embodiment, the detection delay time of the paper sensor 40 (100 ms)
ec) to determine the transport amount of the recording paper P in
Although an interrupt process is performed every msec to rewrite a new transport amount, the interval at which the interrupt process is performed is not limited to 10 msec. For example, 5msec
Or a multiple of 100 msec, such as 20 msec, or the like, and the shorter the interval of the interrupt processing, the smaller the detection error of the recording paper transport amount can be. In the above embodiment, the correction buffer area 4
By storing ten transport amount data obtained every 10 msec in 3b, the recording paper transport amount during the detection delay time of the paper sensor 40 is obtained. In the correction buffer area 43b, the latest transport amount data obtained by the interrupt processing is temporarily stored in a register or the like.
Only the three data of the sum of the ninth transport amount data from the second transport amount data and the oldest transport amount data may be stored.

In the above embodiment, the paper sensor 4
Although the detection delay time of 0 is set to 100 msec, it goes without saying that the detection delay time differs depending on the performance of the paper sensor used in the paper transport mechanism. Even if the detection delay time is not 100msec,
The interval at which the above-described interrupt processing is performed may be such that a multiple thereof becomes the detection delay time. For example, if the detection delay time is 80 msec, interrupt
The recording paper conveyance amount within the detection delay time may be detected by performing the operation eight times at 0 msec intervals.

[0028]

As described above, according to the paper transport mechanism of the first aspect, the number of transport steps of the transport means between the leading edge detection signal and the trailing edge detection signal of the recording paper is determined by the paper sensor to determine whether the recording paper has been moved. Because the length of the recording paper is obtained by subtracting the number of transport steps by the transport means within the detection delay time of the paper sensor before the time when the edge detection signal is obtained, recording is performed only by the counter value of the counter. Occurred when asking for paper length,
The detection error caused by the detection delay time of the paper sensor is corrected. Thus, even if the recording paper is intermittently transported, the length of the recording paper being transported can be accurately detected. Therefore, when recording is performed on a recording sheet, a predetermined margin can be accurately provided at the end of the sheet, and the recording can be accurately completed within a guaranteed recording range.

According to the paper transport mechanism of the present invention, the number of transport steps within the delay time is stored in each of the plurality of areas of the storage means. The number of transport steps within the delay time stored in the storage means at the time when the trailing edge detection signal of the recording paper is detected by the paper sensor, and the actual number of transport steps within the delay time Can be kept within the range of the number of transport steps within the predetermined interval. Accordingly, the number of transport steps stored in the storage unit at the time when the trailing edge of the recording paper is detected becomes closer to the actual number of transport steps, and the length of the recording paper can be detected more accurately.

According to the paper transport mechanism of the present invention, each time the number of transport steps of the latest interrupt processing is obtained, this transport step number and the oldest transport step number are rewritten. In the means, the number of transport steps within the latest delay time can be stored, and a simple circuit configuration is required for that purpose.

According to the paper transport mechanism of the present invention, the occurrence of a paper jam is determined based on the counter value of the counter. Therefore, a counter for detecting the length of the recording paper and a paper jam are provided. Can be used in combination with a sensor for detecting the occurrence of the phenomenon. Therefore, a separate device other than the paper jam detection counter is not required to detect the recording paper length according to the present invention, and the manufacturing cost of the paper transport mechanism can be reduced.

[Brief description of the drawings]

FIG. 1 is an external view of a recording apparatus equipped with a paper transport mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view of the recording apparatus.

FIG. 3 is a schematic block diagram of the recording apparatus.

FIG. 4 is a diagram illustrating a RAM provided in the paper transport mechanism.

FIG. 5 is a flowchart illustrating a flow of a process when the recording paper length is detected by the paper transport mechanism.

FIG. 6 is a diagram showing a use state of a recording paper length correction buffer in the RAM.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording device 5 Recording part (recording means) 34, 36 Paper feed roller (conveyance means) 40 Paper sensor 41 Control part (recording paper length detection means, storage means) 43 RAM (storage means) 47 Transport motor (conveyance means) 48 Jam Counter (Counter)

Continued on front page F-term (reference) 2C058 AB03 AB04 AB15 AC07 AC11 AD03 AD04 AF20 GB01 GB09 GB14 GB17 GB20 GB22 GB31 GB32 GB48 GE03 2C059 AA00 AA05 AA51 AA54 AA55 3F048 AA02 AA04 AA05 AB01 BA07 BA14 BC08 CA03 CC03 CB033 FC03 KB20 MA26 MA36 MC10

Claims (4)

[Claims] 1. A recording apparatus, comprising: a recording device having recording means for performing recording on a predetermined line unit in a direction orthogonal to a recording paper transport direction; a transport means for intermittently transporting the recording paper; and an upstream side of the recording means. And a paper sensor having a paper sensor for detecting the leading and trailing edges of the recording paper conveyed by the conveying means, wherein a trailing edge detection signal is obtained from the time when the leading edge detection signal of the recording paper is obtained by the paper sensor. A counter that counts the number of transport steps of the transport unit until the time when the recording paper is obtained, and a detection delay time of the paper sensor before the time when the trailing edge detection signal of the recording paper is obtained by the paper sensor. Storage means for counting and storing the number of transport steps by the transport means; storing in the storage means the number of transport steps counted by the counter And a recording paper length detecting means for calculating the length of the recording paper by subtracting the number of transport steps performed. 2. The storage unit according to claim 1, wherein at least the number of transport steps within a time corresponding to the delay time is divided into a plurality of areas in a time series and stored. 2. The paper transport mechanism according to claim 1, wherein the number of transport steps for the set time is stored by interruption processing at predetermined intervals. 3. The storage unit stores at least the number of transfer steps of the latest interrupt processing in the first area and shifts out the oldest number of transfer steps stored in the last area. 3. The paper transport mechanism according to claim 2, wherein the number of transport steps corresponding to the delay time is stored. 4. When the trailing end of the recording paper is not detected by the paper sensor when the counter value of the counter reaches a predetermined value, it is determined that a paper jam has occurred in the recording paper. The paper transport mechanism according to claim 1.