JPH07112900B2 - Recording sheet supply control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet supply control device for supplying a recording sheet to a recording device such as a copying machine, and particularly when the sheet conveying path is relatively long. With respect to a process for supplying a sheet as a matter of course.

[Prior Art] In general, a copying machine has a paper feed tray or a paper feed cassette that holds a large number of recording sheets in an overlapping state, and a paper feed mechanism is provided in the vicinity of the paper feed tray or paper feed cassette to make a paper feed request. Each time, one recording sheet is fed out. The recording sheet fed by the paper feeding mechanism is temporarily stopped in contact with a registration roller located downstream of the path, and the registration roller is at a predetermined timing synchronized with the progress of the process of the copying machine. Send out the recording sheet.

Some recent copying machines are equipped with a large number of paper feed trays and paper feed mechanisms, in which a transport mechanism is further interposed between each paper feed mechanism and the registration rollers. In addition, a copying machine that automatically performs double-sided copying is equipped with a double-sided tray that holds recording sheets for which single-sided copying has been completed.

In a copying machine having a large number of paper feed trays and a double-sided tray, the conveyance path of recording paper becomes very long. Therefore, it takes a considerably long time from the start of the paper feeding operation until the recording paper reaches the predetermined position. Therefore, when the paper feed operation is started after the copy start instruction is issued, it takes a long time to make one copy. So, from the past,
In the copy operation for the second and subsequent sheets in the case of performing continuous copy, the copy speed is increased by controlling the feeding operation of the next recording paper before the end of one copy cycle.

Specifically, for example, the following is performed. The cycle of the paper feeding operation is the same as the recording cycle of the recording system. When the paper feeding operation is started, first, the paper feeding mechanism is driven to feed one sheet of recording paper, and when the paper feeding sensor located immediately downstream (downstream) of the paper feeding mechanism detects the leading edge of the recording paper, the paper feeding mechanism is temporarily stopped. When the paper feed operation is stopped and the time after the start of the paper feed operation reaches a predetermined time, the paper feed mechanism is driven again, and the fed recording paper is delivered to the transport mechanism located downstream of the paper feed mechanism, and then the paper feed mechanism is driven. To stop.
The transport mechanism is constantly driven. The leading edge of the recording paper transported by the transport mechanism comes into contact with the registration rollers located downstream of the transport mechanism and stops. The registration roller is
Driving is started in synchronization with the progress of the operation of the recording system, and the fed recording paper is sent out to the recording system. The recording paper is deformed in a state in which the leading end portion is slightly slackened with the leading end abutting the registration roller, but is normally sent out by the registration roller before the deformation amount becomes large.

In this type of paper feeding system, if the recording paper actually reaches the registration roller too early, a large slack will occur in the recording paper, causing jamming or bending. Further, if the timing at which the recording paper reaches the registration rollers is late, the paper feed may be unsuccessful or the position of the recording paper may deviate from the position of the recording image. That is, a large change is not allowed in the time from the start of the paper feeding operation until the recording paper reaches the registration rollers. However, in general, it is inevitable that some slippage will occur due to the slip between the rollers of the paper feed mechanism and the recording paper. Therefore, in the above example, the paper feed mechanism is temporarily stopped after the paper feed sensor detects the recording paper, and the positional deviation is corrected by the stop time. Therefore,
In this case, a paper feed sensor is indispensable for each paper feed mechanism.

Further, in the paper feed system having a long paper feed path for recording paper as described above, in the case of continuous paper feed operation, there may be two or three recording papers in one paper feed passage. In that case, if a jam occurs and the device stops, many recording papers will remain in the device, and it is difficult to remove the recording papers.
A large number of recording sheets are wasted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording sheet supply control device in which the paper feed mechanism and the transport mechanism are simple in structure and the paper feed operation is reliable.

[Configuration of the Invention] In order to achieve the above object, in the present invention, when the sheet is continuously supplied, the drive control of the sheet feeding means is performed at a cycle of Ta− (Tc + Td); and the sheet is Tb + Tc. If it exists between a position upstream of the registration means by a distance equivalent to time and a position corresponding to a time Tb time before the driving start time of the registration means, until the sheet comes out of the range, the sheet The start of drive control of the feeding means is delayed.

Here, Ta is the recording cycle of the recording system in the case of continuous recording of a plurality of sheets, Tb is the time from when the sheet feeding means starts the feeding operation until the sheet on the sheet holding means reaches the sheet conveying means, Tc is a margin time of the sheet feeding means, and Td is a sheet stop time in the registration means.

By doing this, the paper feed operation cycle is shorter than the recording system operation cycle by Tc + Td, so even if the actual paper feed is delayed a little due to paper slip in the paper feed system, the delay is Tc + Td. The paper can be absorbed and supplied to the recording system from the resist means in accordance with the operation of the recording system.

Also, when the recording paper exists near the registration means,
Since the start of the paper feeding operation is delayed, the cycle of the paper feeding operation becomes the same as the operation cycle of the recording system as a whole when this delay is included. Further, as a result, the next sheet feeding operation is prohibited until it is confirmed that the sheet located at the most downstream side (near the registration means) of the sheet feeding system is normally completed. In case of occurrence of, the number of papers remaining in the paper feed system is minimized.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[Embodiment] FIG. 1 shows one type of copying machine embodying the present invention. A description will be given with reference to FIG. In brief, this copier consists of the copier body, ADF (Automatic Document Delay Device) 60, sorter.
70, automatic double-sided processing unit 80 and other optional units.

The sheet feeding system for supplying the recording sheets has five stages. That is, the first sheet feeding system and the second sheet feeding system are provided in the main body of the copying machine, and the second sheet feeding unit 170 and the fourth sheet feeding unit 170 which are the third sheet feeding system.
A third paper feeding unit 180 including a paper feeding system and a fifth paper feeding system is connected to the copying machine main body. 21, 22, 23 and 24 are cassettes provided in the first paper feeding system, the second paper feeding system, the third paper feeding system and the fourth paper feeding system, respectively, and 25 is a tray of the fifth paper feeding system. is there.

When copying on the back side in the double-sided processing mode, the double-sided tray 81 provided in the automatic double-sided processing unit 80 is used.

FR1, FR2, FR3, FR4, FR5 and FRd are the first paper feed system, the second paper feed system, the third paper feed system, the fourth paper feed system, the fifth paper feed system and the double-sided paper feed system, respectively. It is a paper feed roller equipped with. Each of these paper feed rollers is connected to the main motor 40 via a paper feed clutch (electromagnetic clutch).

In this example, regarding the first paper feeding system and the second paper feeding system, the recording paper delivered by each paper feeding roller is directly supplied to the registration roller 27. However, regarding the other paper feeding systems, the recording paper fed by the respective paper feeding rollers is fed to the registration rollers 27 through the paper feeding transport system TRU having a relatively long transport distance. A large number of transport rollers provided in the paper feed transport system TRU are coupled to each other and connected to the main motor 40 via a transport clutch (electromagnetic clutch).

The registration roller 27 is connected to the main motor 40 via a registration clutch (electromagnetic clutch). At a position slightly upstream (upstream) of the registration roller 27,
A registration sensor for detecting the presence or absence of recording paper is provided.

A contact glass 1 on which a document is placed is provided at the top of the main body of the copying machine, and an optical scanning system 30 is provided below it. The optical scanning system 30 includes an exposure lamp 31, a first mirror 32,
A third mirror 33, a fourth mirror 34, a lens 35, a fifth mirror 36, a slit 37, etc. are provided. When performing document scanning, the first carriage equipped with the exposure lamp 31 and the first mirror 32 and the second carriage equipped with the third mirror 33 and the fourth mirror 34 are set to 2: so that the optical path length does not change. Scanned mechanically at a relative speed of 1. The lens 35 is a zoom lens, and its magnification can be changed by driving a motor.

Therefore, the light emitted from the exposure lamp 31 is imaged on the photosensitive drum 2 through the first mirror 32, the third mirror 33, the fourth mirror 34, the lens 35, the fifth mirror 36 and the slit 37. .

Around the photosensitive drum 2, there are provided a main charger 3, an eraser 4, a developing device 5, a pre-transfer charge eliminating lamp 6, a transfer charger 7, a separation charger 8, a knealing unit 9, and the like.

The image reproduction process will be briefly described. The surface of the photoconductor drum 2 is uniformly charged to a predetermined high potential by the discharge of the main charger 3. The eraser 4 erases the charges of the portion not used for image reproduction. When the charged surface of the photoconductor drum 2 is irradiated with the reflected light from the original, the potential of that portion changes (decreases) according to the intensity of the irradiated light. The photoconductor drum 2 rotates in the direction shown by the arrow in the figure, and the optical scanning system 30 sequentially scans the document surface in synchronization with it, so that the density (light reflectance) of the document image is formed on the surface of the photoconductor drum 2. A potential distribution corresponding to the distribution, that is, an electrostatic latent image is formed.

When the portion on which the electrostatic latent image is formed passes near the developing device 5,
The toner in the developing device 5 is adsorbed on the surface of the photoconductor 2 according to the potential distribution, whereby the electrostatic latent image is developed and a visible image corresponding to the electrostatic latent image is formed on the photoconductor drum 2. It On the other hand, in synchronization with the progress of the copy process, the recording sheet is supplied from any one of the six paper feeding systems selected.
The recording sheet is fed via the registration roller 27 so as to overlap the surface of the photosensitive drum 2 at a predetermined timing.

Then, the transfer charger 7 transfers the visible image (toner image) on the photosensitive drum 2 to the recording sheet side, and the separation charger 8 separates the recording sheet on which the visible image is transferred from the photosensitive drum 2. To do. The separated recording sheet is conveyed to the fixing device 12 by the conveyor belt 11. After passing through the fixing device 12, the toner image on the recording sheet is fixed on the fixing device 12.
It is fixed on the recording sheet by the heat inside. The recording sheet which has been fixed is discharged to the sorter 70 or the automatic double-sided unit 80 through a predetermined discharge path.

FIG. 2 shows a schematic electric circuit configuration of the copying machine shown in FIG. Referring to FIG. 2, a microcomputer unit is provided as a main control unit 100, to which various devices are connected.

The main control unit 100 includes a microprocessor 110, a read only memory (ROM) 120, a read / write memory (RAM) 130,
It has an I / O port 140, an A / D converter 150, and a serial I / O unit 160.

The main control unit 100 includes an automatic document feeder 60, a sorter 7
0, automatic double-sided processing unit 80, operation board 203, optical system control unit 204, high-voltage power supply unit 205, heater / lamp control unit 207, signal processing circuits 208, 210, and drivers 209, 21
1 is connected.

A timing pulse generator TPG and a registration sensor SEN1 are connected to the signal processing circuit 208. The timing pulse generator TPG is composed of a disc connected to the drive shaft of the main motor 40 and a transmission type optical sensor arranged in the vicinity of the disc. Many openings (slits) are formed in the disc, and when the main motor 40 rotates,
Since the disk rotates and a large number of slits sequentially cross the optical path of the transmissive optical sensor, the timing pulse generator TPG outputs a number of electric pulses corresponding to the rotation amount. The registration sensor SEN1 is the registration roller 27
It is located in the vicinity of and outputs an electric signal according to the presence or absence of recording paper.

The driver 209 includes a sheet feeding clutch CL1 of the first sheet feeding system and a second sheet feeding clutch CL2.
Paper feed clutch CL2 for paper feed system, paper feed clutch CL for third paper feed system
3, the paper feed clutch CL4 of the fourth paper feed system, the paper feed clutch CL5 of the fifth paper feed system, the paper feed clutch CLd of the double-sided paper feed system, the transfer clutch CLt, the registration clutch CL reg, and the main motor 40 are connected. ing.

The signal processing circuit 208 is connected with a large number of sensors such as a sensor for detecting the presence / absence of paper in each paper feed system, a sensor for detecting the size of paper in each paper feed system, a toner density sensor, and a document density sensor. Various clutches, relays, solenoids, etc. are connected to the driver 211.

FIG. 3 shows a schematic operation of the main control unit 100 shown in FIG. This will be described with reference to FIG.

When the power is turned on, first an "initialization" process is performed. In this process, the contents of the memory 130 are cleared, the state of each input port is read, and the contents of the memory 130 and the state of the output port are set to the initial state based on the read result and predetermined initial data.

When the "initialization" process ends, the "wait mode" process proceeds. Reading the status of each input port, heater temperature control,
Display processing and so on. In this operation mode, the temperature of the fixing heater is mainly controlled. The display on the operation board 203 becomes "please wait", indicating that copying is not possible. Also, key input is not accepted. This process is repeated until the temperature of the fixing heater stabilizes. However, if an abnormality is found, the process proceeds to "abnormal mode" processing. If the heater temperature does not reach the target range even after the lapse of a predetermined time or more, the process proceeds to "standby mode" processing.

In the "standby mode" processing, energization of all loads other than the fixing heater and the display is prohibited, and temperature control and display control of the fixing heater are mainly performed.

In the "abnormal mode" processing, energization of all loads other than the display unit is prohibited, a display is made according to the content of the abnormality, and the process waits until the abnormality is cleared.

When the temperature of the fixing heater is stabilized within a predetermined temperature range in the "wait mode" process, the process proceeds to the next "ready mode" process. In this processing, the status reading of each input port, key input processing, heater temperature control, display processing, etc. are performed. In this mode, the display on the operation board 203 is "copy ready", and key input from the operation board 203 is accepted. Therefore, for example, when setting the number of copies, this mode is set. This process is repeatedly executed until the print start key on the operation board is pressed.

When the print start key is pressed in the "ready mode" process, the process proceeds to the next "pre-copy mode" process. In the "pre-copy mode" processing, the cleaning processing of the photosensitive drum and the control of a part of the paper feeding system, which are necessary before starting the copying process, are performed. That is, regarding the third paper feed system, the fourth paper feed system, the fifth paper feed system, and the double-sided paper feed system, since the paper transport path is long, the paper feed control should be performed before the actual copying process is started. Start.

When the "pre-copy mode" process is completed, the process proceeds to the next "copy mode" process. In this "copy mode" process, most of the copy process is performed. Paper feed start control of the first paper feed system and the second paper feed system is processed in this mode.

When the copy process for one sheet is completed in the "pre-copy mode" process, the process proceeds to the next "copy end mode" process.
In the "copy end mode" processing, various kinds of processing required until the paper, which has completed the copying process, is discharged to the sorter 70 or the automatic duplex processing unit 80.

When the "copy end mode" processing is completed, the "wait mode" processing is performed again. In this case, since copying is possible, the process immediately proceeds to "ready mode" processing. If the number of copies is set to two or more, the same state as when the print start key is pressed is reached, and the process immediately proceeds to the next "pre-copy mode" process to repeat the copy operation.

A specific operation will be described below mainly regarding the processing of the paper feeding system. The contents of the "pre-copy mode" process in FIG. 3 will be described with reference to FIG. 4a.

First, initial conditions are set. That is, various flags necessary for starting the copy process are initialized. Next, set the contents of the set number counter CN set to the paper feed counter CNf.
To turn on the main motor 40. The set number counter CN set stores the number of copies set by key input from the operation board in the "ready mode" process.

Next, the "initial paper feed" subroutine is executed. And
If there is no abnormality, the flag Fprc is checked, and if it is "0", pre-copy cleaning processing is performed. The flag Fprc is "0" in the initial state, and is set to "1" when the pre-copy cleaning process is completed. Next, the flag Fok is checked, and if it is "0", the "feed standby" subroutine is executed. The flag Fok is "0" in the initial state, and is set to "1" when the predetermined paper feeding process is completed in the "pre-copy mode" process. Furthermore, flag F
When both prc and Fok are "1", the flag Fcomp is set to "1" and the timing pulse counter CND is cleared to 0. The flag Fcomp is referred to when determining whether the pre-copy mode is completed.

Details of the "initial paper feed" subroutine of Figure 4a will be described with reference to Figure 4b. In this process, first, the paper feed system is determined. If the selected paper feed system is the first paper feed system or the second paper feed system, the following processing is skipped. Timing pulse counter if other paper feed system is selected
Start counting CNA, CNB and CNC. Then, the transport clutch CLt is turned on, and the paper feed counter CNf is decremented (-1). Further, if the selected paper feed system is the double-sided paper feed system, the third paper feed system, the fourth paper feed system, and the fifth paper feed system, the double-sided paper feed clutch CLd, the third paper feed clutch CL3, and the fourth paper feed clutch CL3, respectively.
The paper feed clutch CL4 and the fifth paper feed clutch CL5 are turned on.

Details of the "paper feed control" subroutine of FIG. 4a will be described with reference to FIG. 4c. In this process, first, the paper feed system is determined. If the selected paper feed system is the first paper feed system or the second paper feed system, the following processing is skipped. If any other paper feed system is selected, "pulse count", "paper feed clutch off", "next paper feed on", "paper feed clutch disable",
Each subroutine of "paper feed clutch on" and "transport clutch off" is executed.

The contents of the "pulse count" subroutine are shown in Figure 4d. Please refer to FIG. 4d. In this process, when there is a pulse input from the timing pulse generator TPG, it is counted and the contents of various counters (registers) are updated.
First, the content of the counter CNS is incremented. Then, the counter CND is incremented. Further, the state of the transport clutch CLt is checked, and when it is turned on, the contents of the counters CNA, CNB and CNC are incremented respectively.

If the transport clutch CLt is off, the paper feed clutch C
Check the status of Lf (either CL3, CL4, CL5 or CLd). If the paper feed clutch is on, the content of the counter CNA is incremented. That is, the counter CNA counts the timing pulse when either the transport clutch or the paper feed clutch is on, and the counters CNB and CNC count the timing pulse only when the transport clutch is on.
The counter CNS is cleared to 0 when the registration sensor detects the leading edge of the paper, and the CND is cleared to 0 when the flag Fok becomes "1". The content of the "paper feed clutch off" subroutine is shown in FIG. 4e. This will be described with reference to FIG. 4e.
In this process, first, the paper feed system is determined, and the process according to the result is performed. When the double-sided processing paper feed system is selected, the content of the timing pulse counter CNA is compared with 80. If CNA> 80, turn off the paper feed clutch CLd.

When any one of the third paper feeding system, the fourth paper feeding system and the fifth paper feeding system is selected, the content of the counter CNA is set to 70.
Compare with. If CNA> 70, paper feed clutch CL3, CL4 and CL
Turn off 5 respectively.

The content of the "next paper feed on" subroutine is shown in Fig. 4f. First
This will be described with reference to FIG. In this process, first, it is confirmed that the paper feed counter CNf is not 0, and if CNf is not 0, the next process is performed.

The selected paper feed system and the size of the paper in the paper feed system are determined. When the double-sided paper feed system is selected and the paper size is A5, A4, A3, ..., the content of the timing pulse counter CNA is 323, 507, 760, ..., respectively.
・ Compare with. And, for example, when the paper size is A5,
When the timing pulse counter CNA exceeds 323, "1" is set in the paper feed request flag Ffon.

If any of the third paper feed system, the fourth paper feed system, and the fifth paper feed system is selected and the paper size is A5, A4, A3, ... 313,497,750, ...
・ Compare with. And, for example, when the paper size is A4, CNT
If it is> 497, "1" is set to the paper feed request flag Ffon.

Fig. 4g shows the contents of the "prohibit paper feed clutch" subroutine. Refer to FIG. 4g. First, the selected paper feed system is determined. In the case of the double-sided processing sheet feeding system, the contents of the timing pulse counters CNA, CNB and CNC are compared with 535. CNA, C
If the content of any one of NB and CNC is 535, the paper feed prohibition flag Fdis is set to "1".

Similarly, in the case of the third paper feed system, if the content of any one of CNA, CNB, and CNC is 210, the flag Fdis is set to "1", and in the case of the fourth paper feed system, If the content of any one of CNA, CNB, CNC is 410, the flag Fdis is set to "1", and in the case of the fifth sheet feeding system, the content of any one of the counters CNA, CNB, CNC is predetermined. If the value is N5, the paper feed prohibition flag F
Set dis to "1".

The contents of the "paper feed clutch on" subroutine are shown in Fig. 4h. Refer to FIG. 4h. In this process, first, the paper feed request flag Ffon is checked. When Ffon is "1", that is, when there is a paper feed request, the paper feed prohibition flag Fdis is checked next. If Fdis is "0", that is, if the paper feed is not prohibited, the next paper feed system is determined.

In case of double-sided paper feed system, turn on the paper feed clutch CLd,
In the case of the third paper feed system, the paper feed clutch CL3 is turned on, and the fourth
In the case of the sheet feeding system, the sheet feeding clutch CL4 is turned on, and in the case of the fifth sheet feeding system, the sheet feeding clutch CL5 is turned on. Then, when any one of the double-sided processing paper feeding system, the third paper feeding system, the fourth paper feeding system, and the fifth paper feeding system is selected, the following processing is further performed.
First, the transport clutch CLt is turned on, the paper feed counter CNf is decremented, the contents of the counter CNB are transferred to the CNC, the contents of the counter CNA are transferred to CNB, and the contents of the counter CNA are cleared to 0.

The contents of the "transport clutch off" subroutine are shown in FIG. 4i. Refer to FIG. 4i. In this process, first, the state of the registration sensor SEN1 is checked. When SEN1 is off, that is, when there is no recording sheet near the registration roller 27, the flag Fcns is reset to "0". When the registration sensor SEN1 is turned on, that is, when the recording sheet exists near the registration roller 27, the following processing is performed. First, the flag Fcns is checked. Immediately after the registration sensor SEN1 detects the leading edge of the recording sheet, the flag Fcns is "0", so the counter CNS is cleared to 0 and the flag Fcns is set to "1". When the content of the counter CNS reaches 20, the conveyance clutch CLt is set to OFF.

The contents of the "wait for paper feed" subroutine in FIG. 4a are shown in FIG. 4j. Refer to FIG. 4j. In this process, first, the selected paper feed system is determined. In case of double-sided paper feed system,
Timing pulse counters CNA, CNB and CNC contents 542
Compare with. One of the contents of CNA, CNB and CNC is 54
If it is 2, the paper feed OK flag Fok is set to "1".

Similarly, in the case of the third paper feed system, if the content of any one of CNA, CNB, and CNC is 217, the flag Fok is set to "1", and in the case of the fourth paper feed system, If the content of any one of CNA, CNB, and CNC is 417, the flag Fok is set to "1", and in the case of the fifth sheet feeding system, any one of CNA, CNB, and CNC is set.
If the contents are the predetermined value N5 + 7, the flag Fok is set to "1".

Referring again to FIG. When the above-mentioned "pre-copy mode" processing is completed, the processing shifts to "copy mode" processing. In this "copy mode" process, a substantial copy process process is performed. This processing includes a "paper feed control" subroutine shown in FIG. 4c, a "registration clutch on" subroutine shown in FIG. 4k, and paper feed processing for the first paper feed system and the second paper feed system. . The sheet feeding process for the first sheet feeding system and the second sheet feeding system is simpler than the process for the other sheet feeding systems described above, and therefore, illustration and description thereof will be omitted.

The contents of the "registration clutch on" subroutine will be described with reference to FIG. 4k. In this process, first, the state of the registration sensor SEN1 is checked. If SEN1 is off, that is, if there is no recording paper at the registration position, the contents of counter CND are checked. Then, when the counter CND is 24, the paper feed prohibition flag Fdis is reset to "0". If SEN1 is on, that is, if there is a recording sheet at the registration position, the content of the counter CND is compared with 84. Then, if CND = 84, the registration clutch CLreg is turned on and the conveyance clutch CLt is turned on.

At the start of the actual copying process, the counter CND
When counting starts, that is, timing pulse counter CN
When any of the contents of A, CNB, and CNC becomes 542, at that time, the exposure lamp 31 is turned on, the main charger 3 is turned on, and the scanning of the optical scanning system 30 is started.

Next, the overall operation of the paper feeding system will be described with reference to FIG. The concrete numerical values in this example are as follows.

(A) One pulse output from the TPG corresponds to 1 mm of the moving distance of the drive system.

(B) The copy speed is as follows.

A3 size vertical feed: 17 CPM (sheets / minute) A4 size vertical feed: 25 CPM A5 size horizontal feed: 38 CPM (c) Paper feed / feed speed is 224 mm / sec (d) Chart paper The stop time of the recording paper from when the registration roller 27 reaches the registration roller 27 to when the registration roller 27 starts is usually 0.05 sec (e) The slack amount of the recording paper reaching the registration roller 27 is
Usually, it is 10 to 15 mm. FIG. 5 shows a case where A5 size recording paper is continuously fed from the double-sided paper feeding system. Therefore, an operation example in that case will be described. In this case, the distance from the paper feed roller to the registration roller is 615 mm (= 615 pulses).

When the paper feeding operation is performed, first, the counters CNA, CNB, and CNC are cleared and then counting thereof is started, the transport clutch CLt is turned on, and the paper feeding clutch CLd is turned on (see FIG. 4b). If no slip occurs between the recording paper PAP1 to be fed and the paper feed roller FRd, the recording paper PAP1 reaches the first conveyance roller in 60 pulses after starting the paper feeding operation.

In this example, in consideration of the possibility of slippage, 20 pulses for margin are added to 60 pulses, and when the counter CNA exceeds 80, the paper feed clutch CLd is turned off (see FIG. 4e). Therefore, the recording paper PAP1 is reliably delivered to the first transport roller before the paper feed clutch CLd is turned off, and the recording paper PAP1 is further transported by the transport roller.

Since the paper size of the recording paper PAP1 is A5, when the content of the counter CNA exceeds 323, the paper feed request flag Ffon is set to "1" (see FIG. 4f).

When the paper feed request flag Ffon becomes "1", the paper feed prohibit flag Fdis is initially "0", so the paper feed clutch CLd is turned on (see FIG. 4h). As a result, the next recording paper PAP2
Sheet feeding operation is started. Also, the transport clutch CLt is turned on. Then, the content of the counter CNA is changed to another counter C.
Move to NB and clear CNA to 0. Therefore, the recording paper PAP1
Position information (the number of pulses) is continuously counted by the counter CNB, and the counter CNA starts counting position information of the new recording paper PAP2.

Therefore, unless the paper feed prohibition flag Fdis becomes "1",
The paper feeding operation is repeated at a cycle of 323 pulses. Note that 3
The value of 23 is predetermined by the following formula.

TF = Ta- (Tc + Td) (1) However, TF: Paper feed cycle, Ta: Copy cycle, Tc: Margin time, Td: Stop time at resist section In other words, Ta = Conveyance speed [mm / sec] / copy speed [CPM] = 224 / (38/60) = 353.7 [pulses, mm] Tc = 20 [pulses, mm] Td = transport speed x stop time = 224 x 0.05 = 11.2 [pulses, mm] Therefore, TF = 353.7- (20 + 11.2) ≈ 323 [pulse, mm].

Also, if any of the counters CNA, CNB, CNC becomes 535,
The paper feed prohibition flag Fdis is set to "1" (Fig. 4g).
The paper feed prohibition flag Fdis is reset to "0" when the registration sensor SEN1 is off and the counter CND reaches 24 (Fig. 4k). When the flag Fdis is "1",
Even if the paper feed request flag Ffon is set to "1",
That is, the sheet feeding operation is not started even at the sheet feeding timing according to the sheet feeding cycle TF. After that, the flag Fdis is "0"
Then, the paper feeding operation is started. That is, the flag Fdis
While is “1”, the start of the next paper feeding operation is delayed from the scheduled timing according to TF.

The timing Tset for setting the flag Fdis to "1" is predetermined by the following equation.

Tset = Tmax- (Tb + Tc) (2) Here, Tmax is the time corresponding to the distance between the paper feed registration rollers, and Tb is the time corresponding to the distance between the paper feed conveyance rollers.

Specifically, since Tmax = 615, Tb = 60, Tc = 20,
When set = 535 and the content of any of the counters CNA, CNB, and CNC reaches 535, the flag Fdis is set to "1".

That is, the flag Fdis is set when the recording paper reaches the position 80 pulses before the registration roller.

On the other hand, when the content of any of the counters CNA, CNB, and CNC reaches 542, the flag Fok is set to "1" (Fig. 4j). F
When ok becomes "1", the counter CND is cleared to 0 (Fig. 4a). That is, the counter CND is the counter CNA, CN
Restart when either B or CNC reaches 542.

The timing Tcnd for clearing CND to 0 is determined in advance as follows.

Tcnd = Tmax- (Tstart-Td) (3) However, Tstart is the time from the start of the copying process to the start of driving the registration roller, and in this example, 83.8.
[Pulse].

In other words, Tcnd = 615- (83.8-11.2) ≈542 [pulse].

Since the flag Fdis is reset to "0" when the counter CND reaches 24, the flag Fdis is set to "0" at the time of 566 pulses in terms of the relative time from the start of driving the paper feed roller. Will be reset. That is, the paper feed prohibition state is released at the timing when the paper theoretically reaches the position of 49 pulses before the registration roller (that is, at the time of 84 pulses before the start of the registration roller drive).

In addition, the recording paper advances further, and the registration sensor SEN1
When PAP1 is detected, the counter CNS is cleared to 0 when it is detected for the first time. That is, the counter CNS restarts counting when the registration sensor detects the leading edge of the paper. When the counter CNS reaches 20, that is, when 20 pulses elapse after the registration sensor detects the leading edge of the paper, the transport clutch CLt is turned off (FIG. 4i).

Therefore, after the leading edge of the paper comes into contact with the registration roller and stops, the transport roller further advances the rear portion of the recording paper by a predetermined amount. As a result, the recording paper comes into contact with the registration roller at its leading edge and stops in a state of being slightly deformed so as to have a slack of about 10 to 15 mm.

The registration roller starts driving when the content of the counter CND reaches 84 (Fig. 4k).

In the case of this embodiment, the cycle TF of the sheet feeding operation is about 71 pulses (Tc + Td) as shown in the equation (1).
Since it is shorter than Ta, it is possible to feed the recording paper to the registration roller with a sufficient margin for the timing of the copy operation. Therefore, even if the recording paper is conveyed with a slight delay due to slippage or the like in each part of the paper feeding system, the paper feeding abnormality does not occur. Further, when the recording paper theoretically exists in the predetermined range near the registration rollers, the start of the next paper feed is delayed until the recording paper is out of the range, so that the actual paper feed cycle corresponds to the cycle of the copy operation. Automatically adjusted.

[Effect] As described above, according to the present invention, since the cycle of the paper feeding operation is sufficiently shorter than the cycle of the recording operation, even if a slip or the like occurs between the drive mechanism and the recording paper in the paper feeding system, the recording timing The recording paper can be sent to the recording system in time. Moreover, it is not necessary to provide a special sensor other than the registration section, and the paper feed roller, the conveyance roller, and the registration roller can be driven at the same speed, so the structure of the drive mechanism is simplified. It can be applied without problems even when there are a plurality of types of sheet lengths and sheet lengths to be fed.

[Brief description of drawings]

FIG. 1 is a front view showing the internal structure of a copying machine of one type embodying the present invention. FIG. 2 is a block diagram showing an electric circuit of the copying machine shown in FIG. FIG. 3 is a flow chart showing a schematic operation of the main control unit 100 of FIG. Figures 4a, 4b, 4c, 4d, 4e, 4f, and
4g, 4h, 4i, 4j and 4k are flowcharts showing details of a part of the operation of the main control unit 100 of FIG. FIG. 5 is a timing chart showing an operation example of one paper feed system of the copying machine of FIG. 1: Contact glass, 2: Photoconductor drum 3: Main charger 21,22,23,24: Cassette 25,81: Tray (sheet holding means) FR1 to FR5, FRd: Paper feeding roller (sheet feeding means) TRU: Paper feeding / conveying system (sheet conveying means) 27: Registration roller (registration means) 30: Optical scanning system, 40: Main motor 70: Sorter 80: Automatic duplex processing unit 100: Main control unit (electronic control means) CL1 to CL5, CLd: Paper feed clutch CLt: Transport clutch CLreg: Registration clutch SEN1: Registration sensor TPG: Timing pulse generator

Claims (3)

[Claims] 1. A sheet holding means for holding a plurality of recording sheets in a stacked state; a sheet feeding means for feeding one sheet on the sheet holding means; and a sheet feeding means provided downstream of the sheet feeding means. Sheet conveying means for conveying the sheet sent out by the conveying means; registration means provided downstream of the sheet conveying means for temporarily stopping the sheet conveyed by the means, and then transmitting the sheet to a predetermined recording system; and the sheet Electronic control means for supplying a recording sheet to the recording system by controlling the feeding means, the sheet conveying means and the registration means;
In the recording sheet supply control device having: a recording cycle of the recording system in the case of continuous recording of a plurality of sheets, from the start of the feeding operation of the sheet feeding means until the sheet on the sheet holding means reaches the sheet conveying means Is Tb, the allowance time of the sheet feeding means is Tc, and the sheet stop time in the registration means is Td; the electronic control means uses the sheet feeding means at a cycle of Ta− (Tc + Td). When the sheet exists between a position upstream of the registration means by a distance corresponding to Tb + Tc time and a position corresponding to a time Tb time before the driving start time of the registration means. Control for delaying the start of the drive control of the sheet feeding means until the sheet comes out of the range. 2. The sheet feeding means, the sheet conveying means and the registration means are connected to one driving source via an electromagnetic clutch, respectively, and the driving source generates a pulse for outputting an electric pulse according to its operation. The electronic control means counts the number of electric pulses output by the pulse generation means, grasps the position of the sheet, and controls the sheet feeding means, the sheet conveying means, and the registration means based on the position. Claim (1) for determining timing
The recording sheet supply control device according to the item. 3. The electronic control means counts the number of electric pulses output by the pulse generation means by a plurality of counting means,
The recording sheet supply control device according to claim (2), wherein counting of pulses of at least one counting means is interrupted when the sheet conveying means is stopped.