JPS5962876A - Variable magnification copying machine - Google Patents

Abstract

PURPOSE:To allow the front end of an electrostatic latent image and that of a copy paper to coincide with each other accurately by setting a timing in relation to an extent of movement for adjustment of a detecting means, which is provided in a scanning path, to control a carrying means. CONSTITUTION:A pair of timing rolls 107 placed before a transfer position hold the copy paper carried from a paper supply device 108, and the front end of the copy paper sent at a proper resist timing coincides with that of an image in the transfer position. A scanning system 1 consists of a scanning optical system 1-1 and a scanning optical system 1-2 which is moved in the half speed of the system 1-1, and the scanning system 1 is moved forward (scans) in the direction of an arrow A and is moved backward (returns) in the opposite direction by a DC motor M1. An encoder 2 generates a pulse signal proportional to the rotation number of the scan motor M1, and the extent of movement and the speed of the scanning system 1 are detected.

Description

[Detailed description of the invention]

The present invention relates to a variable magnification copying machine which performs variable magnification copying by changing the scanning speed of an optical scanning system in accordance with the copying magnification and conveying copy paper at a constant speed. BACKGROUND OF THE INVENTION In general, variable-magnification copying machines use a system in which the circumferential speed of a photoreceptor and the conveyance speed of copy paper are kept constant, and the scanning speed of a document scanning system is varied in accordance with the copying magnification. In this method, the copy paper is transported from a fixed standby position to the transfer position so that the leading edge of the electrostatic latent image formed on the photoreceptor and the leading edge of the transported copy paper coincide at the transfer position. The timing for starting copy paper conveyance has generally been determined from a signal from an original scanning system. However, with this method, when the copy magnification is changed,
Since the scanning speed also changes, the time from the start of scanning to the output of the copy paper conveyance start signal differs depending on the copying magnification and the time from the start of scanning to the output of the copy paper transport start signal.With one detection means, it is difficult to synchronize the leading edge of the electrostatic latent image and the leading edge of the copy paper. A method has been proposed in which a plurality of detection means are provided depending on the copying magnification, and when a certain copying magnification is selected, a signal from the detection means corresponding to the selected copying magnification is used as a copy paper conveyance start signal. In such a method, the detection means is changed in its installation position. Since the timing at which the copy paper transport begins at 15t6 can be easily changed, it has the advantage that it can be easily adjusted even if there are variations in the response time or physical positional relationship of each part depending on the individual copying machine. If the number of detectors is large, the number of detection means increases, resulting in increased cost and disadvantages in that the structure becomes unstructured. In another method, the scanning speed of the scanning system changes as the copying magnification changes, but the circumferential speed of the photoreceptor is always constant. A method has been proposed that focuses on the fact that the time it takes to reach the transfer position is always constant. In other words, a detection means is provided to detect when the scanning system has reached a common document leading edge exposure start position for both copying magnifications, and the copy paper is placed on standby after a certain period of time independent of the copying magnification based on the signal from this detection means. When conveyance is started from the position to the transfer position, the leading edge of the electrostatic latent image on the photoreceptor always coincides with the leading edge of the copy paper, no matter what the copying magnification. This method requires only a profit-taking detection method, so the structure is better than that of the previously mentioned method.
It has the advantage that tSj is simple and the cost is low. However, in this method, the detection means is exposed to the leading edge of the document te1.
Even if the detection means is aligned with the positive and negative images, if there are variations in the response of each part or the physical positional relationship, copy paper transport cannot be started from the detection signal. Generally, this time is constructed as a block diagram of a microcomputer or in other digital circuitry. In such cases, it is extremely difficult to adjust the time for each individual copy. In other words, it is difficult to adjust even a timer made of an electric circuit, and furthermore, if the timer value is set as a microcomputer program, the microcomputer itself must be controlled. The present invention has been made in view of the following drawbacks.The purpose of the present invention is to have a simple structure that can be used even when there are many types of copying magnifications.
To provide a variable magnification copying machine in which the leading edge of an electrostatic latent image and the leading edge of a copy sheet can be accurately aligned at a transfer position and whose synchronization can be easily adjusted. Summary: In order to achieve the second objective, the present invention
The variable-magnification copying surface includes a detection means installed in the scanning path of the scanning means (this position adjustment EI function), a means for measuring the adjustment movement amount of the detection means, and the iMl adjustment amount movement related Q. a timer means having a timer value set, and a control means for activating the timer means by detecting the detection means or the running means and for operating the conveyance means by a timer knob of the timer means. In the copying machine described above, the timer value of the timer means can be changed by adjusting the position of the detection means, so the timing at which the conveyance means is activated can be easily adjusted, and moreover, it can be used for multiple copying magnifications. The basic idea of the present invention will be explained using Figure 1. In Figure 1, the horizontal axis is time (and the vertical axis is short). This is a graph taken between the scanning optical system and scanning means such as the document platen at the original edge exposure start position (origin O) and when the magnification is constant (×1) and when the magnification is varied (×m). This shows the movement locus.Here, switches SW-T and SW- are placed in the scanning path of the scanning means.
13 are installed, each initially at a distance Lo from the origin O.
and Lo-4-LTBo □＼ are provided at different base ξ positions PTo and PBo. Also, the time Tro from when the scanning means passes the document leading edge exposure start position to when the conveying means starts conveying the copy paper, and the switch SW- at the standard position PTo of the scanning means at the same magnification.
Time 1't from turning on T until the conveying means starts conveying the copy paper. Set them respectively. These times are values that can be theoretically determined from design drawings and the like. From the above, the time from turning on the switch SW-T at the scanning means or base position gate O during magnification change (magnification In) to the timing at which the conveying means starts conveying the copy paper (hereinafter referred to as registration timing) is ' rt is expressed as 'rt=Tto+i-tl, where Ttx is the difference in the time when the switch 5W-T is turned on between the same magnification and the variable magnification. Here, the speed of the scanning means at the same magnification is V. Then, L. Ttx = (l − m ) − ■0 Also, L. Since Tro = Tto 10- 0, the time -1-t is L. 1-t='Fro-m-O. If the copying machine is manufactured exactly according to the original design, the tip of the image on the photoreceptor is activated after the timer value ``l''r has elapsed after the scanning means or switch 5W-T is turned on. The leading edge of the copy paper should match at the transfer position. However, even in such a device, there are inherent differences in the response of individual members and assembly errors, and in order to absorb such machine differences, it is necessary to correct the system timing for each copying machine. In this invention, the timing is corrected by the switch 5W.
- Do this by moving T. That is, the switch 5W-T is moved from the reference position PTo to the position PT+, which is a distance Lε away from the reference position PTo.
Furthermore, the timer value is corrected by a correction value Tl that includes the moving distance Lε of the switch SW-'r. Therefore, the new timer value r

[' becomes -rtl=-rt+Ttz-TL3. Since Tt2 is the change in the timer value due to the movement of the switch 5W-T, (2), ε'I'L2: m - (2)0. Here, if the correction value Tta is defined as Lε TL3 = α − 0, the timer value Tt' becomes. Also, the time Tr from when the scanning means passes the document leading edge exposure start position until the corrected registration timing.
' is Tr' = Tro −Tt3·−·−■. According to the formula (■), when the switch s'w--r is moved by a distance Lε from the reference position, the timer value 'I' t ' expressed by the formula (■) is used to obtain the corrected registration timing. It will be a good thing. Therefore, if you adjust the position of switch SW-■ when adjusting the copying machine so that the leading edge of the copy does not shift, the copy paper will be transported with accurate registration timing, and the leading edge of the image on the photoconductor will be aligned with the leading edge of the copy paper. It never shifts. The coefficient .alpha. which determines the amount of correction may be set to an appropriate value by taking into account the movable range of the switches S---T and the accuracy requirements of the timer value. For example, if α is set to a value larger than 1, the timer value can be corrected widely for a certain amount of movement of the switch sw-r, and conversely, if α is set to a value smaller than 1, highly accurate correction can be performed. can. The movement amount ■ and ε of switch s W-T are switch 5W-
It is measured as the difference between the distance LTB after adjusting T and 5W-H and the distance LTBo when both switches are in the reference position. That is, Lε-LTB-LTBO. switch 5W
-B is only used as a reference for calculating the moving amount Lε of the switch SW-T, so its position is arbitrary. The distance can be measured, for example, by using an encoder to measure how many times the shaft of the motor that drives the scanning means or the scanning means rotates while moving between the switches 5W-T and 5W-B. The amount of movement of the switch 5W-T may be measured by other methods. If the copy 1 has a non-volatile memory whose memory contents are not cleared even when the power is turned off, the timer value 1'E' determined as described above should be stored in this memory, and if necessary, the timer value 1'E' should be stored in this memory. It's good to readjust from time to time. However, the memory used in copying machines is generally a volatile memory whose contents are cleared when the power is turned off. In such a case, prior to copying, the scanning means is preliminarily moved back and forth to measure the distance LTB, and a new timer value of 1 is set.
It is a good idea to calculate 'E'. The advantage of this method is that there is no need to use expensive non-volatile memory, and since the timer value is updated at least every time the power is turned on, accurate registration timing can always be obtained regardless of changes in the equipment over time. Examples Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a cross-sectional view schematically showing an electrophotographic copying machine to which the present invention is applied, in which an original placed on the original placing glass (101) is scanned by a scanning system, and its light (image is imaged onto a photosensitive drum (104) by a lens (102) and a mirror (103).The photosensitive drum (104) is uniformly charged in advance by a charger (105), and is irradiated with a light image of the original. and forms an electrostatic latent image corresponding to the document.The electrostatic latent image is turned into toner by a developing device (106) and reaches a transfer position.A pair of timing rollers (107) located before the transfer position is connected to a paper feeding device. (1,08
) (109) is kept on standby, and the copy paper is sent out by measuring the registration timing. The fed copy paper matches the leading edge of the image at the transfer position, one image of toner is transferred by the transfer charger (110), and the photosensitive drum (1,04) is transferred by the separation charter (111).
It is separated from the fixing device Effi (112) and discharged to the outside of the machine. On the other hand, the photosensitive drum (104
), residual toner is removed by a cleaner device (113) and residual charge is erased by an eraser lamp (114), and then the next copying process begins. FIG. 3 is a perspective view showing the scanning system (1) in FIG. 2,
The scanning system (1) consists of a first scanning system (1-1) including an illumination system and a second scanning optical system (1-2) that moves at half the speed of the first scanning optical system. motor,
M+), it is controlled to move forward in the direction of the arrow (hereinafter referred to as scan) and to move backward in the opposite direction (hereinafter referred to as return). (2) is an encoder composed of a Hall element, which is installed on the rotating shaft of the scan motor (Ml) and generates a pulse signal proportional to the number of rotations.The number of pulses moves the scanning system (1). It is a dJ function that detects the distance and the speed of the scanning system (1) at pulse intervals. (SW-II) (SW-1') (SW-
Reference numerals 13) denote a home switch, a timer switch, and a brake switch, which are arranged in this order starting from the home position "Tsukuda" and are activated by the first scanning optical system (1-1) to detect their positions. The home switch (SW-II) issues a scan signal when the first scanning optical system is at the home position (scan start position). The timer switch (SW-T) is provided so that its position can be adjusted.
When turned on by step 1), a timer is activated to start conveying the copy paper. The brake switch (SW-B) is used as a reference to measure the travel amount Lε of the timer switch (SW-T') during scanning, and is used to detect the reference position for braking control during return. It will be done. FIG. 4 shows a control block diagram for reciprocating the scanning system (1). (3) is a microcomputer which is the central part of control.
It consists of a readable and writable random access memory for storing data for braking control, a read only memory, an 8-bit internal counter, an input/output port, etc. (4) is the driver circuit, and the output port (Ho) of the microcomputer (3), (1-11)
The scan motor (IVlt) is controlled by a forward/reverse signal (F/R) and a drive signal (D/S) from the motor. (5)
is a waveform shaping circuit which converts the pulse signal of the encoder (2) into a square wave, and its falling (or rising) signal is inputted to the interrupt terminal (INT) of the microcomputer (3). Reference numeral (6) denotes a reference oscillation circuit which generates a fixed frequency reference pulse for measuring the time interval (FG) of the encoder pulse signal to the external clock terminal (IiCK) of the microcomputer (3). The microcomputer (3) counts the pulses from the reference oscillation circuit (6) using an internal counter, and uses the counted value to control the scan motor (
The rotational speed of Ml), that is, the speed of the scanning system (1) is calculated. On the other hand, (Ml) is a DC main motor for driving the photoreceptor drum, etc. It is connected to a control circuit (9) and a microcomputer (3) by an encoder (2') similar to the scan motor (Ml). The constant speed side fIII is controlled by the pulse signal emitted to the constant speed side fIII. (7) is a DA converter which converts the signal emitted from the output port (Po) into an analog signal based on the pulse from the encoder (2'). (8) is an adder circuit, which connects the DA converter (
The output from 7) and the thread voltage corresponding to the minimum allowable speed are added together to obtain a driving voltage, and this is sent to the control circuit (9),
``Thus, the main motor (Ml) is controlled at a constant speed. Figure 5 shows a specific example of the driver circuit (4). The DC power source (E) is connected to a bridge-connected transistor (T
Tesca 7 motor (Ml) via (Tr4)
diodes (D1) to (1)4) are connected to each transistor (Tr) to form a bypass for the back electromotive voltage.
l) to ('rr 4 ) are connected in parallel. The input terminal (10a) is the one to which the forward rotation signal l1l (IJ, reverse rotation signal "L"') is input, and the antgelt (ANI)
+) and the base of the transistor (Trl), and is connected to the input side of the AND gate (AND2) and the transistor (Tra) via the inverter (11).
connected to the base of. Another input terminal (1
0b) is the one in which the on signal "H" and the off signal "L" are input, and the following signals are input: (ANDl), (ANI)
2) is connected to the input side. Also, the output side of the AND gate (AND l) is a transistor (Trz) (IJ) H-7, IC, and the output side of the AND gate (AND 2) is a transistor (1" r
4) Connected to the base. In the second configuration, in the forward rotation mode (FD), the transistor Crr3) is connected to the input terminal (10a) or '11'.
is turned on, and the AND gate (AND+) is turned on at l-1' of the input terminal (10b), and the transistor (
Trz) turns on, current flows in the direction of arrow (a), and the motor (Ml) rotates in the normal direction. In addition, in the reverse mode (RD), the input terminal (tOa) is switched to "L", the transistor (Trl) is turned on, and the input terminal (tab) is switched to "H".
At 1+, the AND gate (AND2) becomes "H", the transistor (Tr+) turns on, and the current flows in the direction of the arrow (b1), causing the motor (Mt) to reverse. On the other hand, in brake mode (FS) In the reverse state, the input terminal (10a) is switched to "I" and (lQb) is switched to "I-" to turn on only the transistor (Tr3). In this case, the current to the motor (Ml) is cut off. but,
An arrow (al) that attempts to reverse the rotation of the motor (Ml)
A back electromotive force is generated in the direction. This back electromotive voltage flows through the transistor (Tra), the motor (Mt), and the diode (Dl), and acts as a brake against the reverse rotation of the motor (Mt), that is, as a regenerative brake. In addition, the diode (υI)l (D2), (υ3), (D
4) cuts the back electromotive force generated during forward rotation and the back electromotive force generated when switching modes, and
l'r2). (Tra), prevents abnormal voltage from being applied to (Tr4). Here, a feature of the present invention is that the scanning system detects the registration timing for sending out the copy paper waiting at the timing roller position so that its leading edge coincides with the leading edge of the image on the photoreceptor. The registration timing is determined by a timer that is activated when one switch is turned on, and the registration timing is corrected by measuring the movement of the switch whose movement amount is related to the timer value. Also,
The movement of the switch is measured by measuring the distance between it and any switch. As mentioned above, there are various ways to correct the registration timing, but in this embodiment, a preliminary reciprocating motion is set prior to the first reciprocating motion for copying in order to control the braking at the time of return. Since the configuration is such that correction is applied in the next reciprocating motion using the results measured during the previous reciprocating motion, the correction of the registration timing, that is, the calculation of the timer value, is performed during the preliminary forward motion. In addition, in order to shorten the return time and accurately stop at the home position, the braking control at the time of return is such that the timing to apply braking to the scanning system (1) during return at full power is set to the time of braking on the previous return. The system sequentially corrects the measured data and starts braking at the optimal timing. Specifically, after turning on the scanning system (1) or the brake switch (SW-B), the braking delay counter (TM
), the braking is started after a delay of (TM), and this count value (TM) is corrected with the data measured during the previous braking. Braking is performed in the order of regenerative braking and forward braking.
As shown in the figure, when the speed is reduced to a predetermined speed by braking,
It is controlled at a constant speed at that speed and stopped when the scanning system (1) or the home switch (SW-I) is turned on. and,
The displacement during constant speed control is measured and used to correct the braking delay counter (TM). The details will be described later. In this embodiment, the scanning system (1) is a control r11+ during copying.
Therefore, prior to this, a preliminary reciprocating motion (SCAN: A, RETURN) is performed at the start of copying. Reciprocating motion when copying the actual number (S CAN: B,
RETURN) becomes the optimum opening/opening j corrected by the data measured by this preliminary reciprocating movement. Figures 8 to 17 show the microcomputer (
3) is a flow chart diagram of a control program according to FIG. Hereinafter, specific control will be described in detail with reference to this flowchart. First, the main routine shown in FIG.
Explain. When the power is turned on in the microcomputer (3), internal parameters are initialized in step 2, and the copy magnification is set in step 3. Data such as scan size is input, and then data input is repeated until a scan signal is input. When the scan signal is input, "Y14S" is input in step ■.
J is determined, and a subroutine (1-IONiE,
) is processed to ensure that the scanning system (1) is located at the home position (scan start position). Thereafter, in step (2), a subroutine (SCAN:A) is executed, and the scanning system (1) performs a preliminary scan to read data for registration timing correction in the next actual copy scan. Further, in step (2), a subroutine (RETURN) is processed, the scanning system (1) is returned to the hole position, and data for subsequent return is collected. Next, wait for the scan signal to be input in step ■, and if it is determined to be YESJ, process the subroutine (SCAN:B) in step ■, perform the actual copy scan, and from then on depending on the number of copies. Repeat steps ■, ■, ■. Here, constant speed jtill a of the scan motor (Ml)
l will be explained. For constant speed control, an external interrupt is applied to the interrupt terminal (INT) of the microcomputer (3) at the falling edge (or rising edge) of the encoder pulse corresponding to the rotation speed of the scan motor (Ml). Scan time (MTON) calculated using the formula σ0N-)-A (FG-1'G o) according to the interval and the time counted by the internal counter driven by the base r4jξ oscillation circuit (6). This is done by turning on the motor (Ml) (see Figure 7). In addition, (TON) is the reference time when the scan motor (M+) is turned on to keep it at a constant speed, and (FC) is the time interval of encoder pulses measured by the internal counter.
(FGo) is the motor rotation speed and gear ratio. This is a setting value that changes depending on the copy magnification. Therefore, (
A+ is the motor on time due to the error between the set value and the actual measurement (
This is a coefficient that determines the correction amount of MTON). Here, (TON) is (in scan time constant speed control)
FC), and the correction value is further corrected by the value of A
Since the motor on time (MTON) is the value corrected by (FG-1'G o ), the motor on time (+zT
ON) is double corrected to a more appropriate value. In this embodiment, the constant speed control has two types: during scanning and near the end of return. Also, when scanning, the scanning speed varies depending on the copy magnification. The values of (FGO), (A), and ('rON) above are multiple tonal. The timer interrupt and FC interrupt in the constant speed control are scan and return subroutines (Fc; WA IT)
(MCOFF). A timer interrupt occurs every time the internal counter overflows due to a pulse input from the reference oscillation circuit (6) to the external clock terminal (ECK) of the microcomputer (3). The internal counter continues counting from zero again even after overflow. In this embodiment, the circular J counter is 8 bits, and the frequency of the reference oscillation circuit (6) is set to 2QQ.
Since l (l I z), a timer interrupt occurs at 28 = 256 clocks (1,28 ms). This timer interrupt is accepted after the l"G interrupt processing described later, and the processing routine (I NT -r), the motor on time (MTON
) has elapsed, and if it is determined as YES, the drive OFF data is output in step σ and the process returns to the main routine.
) has not passed, in step σIIF, "N
It is judged as OJ and the process returns directly to the main routine. The drive tJFF data is set in the RAM area of the microcomputer (3) when interrupts are permitted, together with the drive ON data executed by the I-'G interrupt processing routine (iNT-t='). 0N-OF
F data is forward/reverse signal (F/R) and drive signal (D/S)
It is a combination of (F) is forward rotation, (10 is reverse rotation, (I)
) means hW mt, (S) means stop. That is, ON data (FD), OFF data (FS) during scanning,
The ON data during constant speed control during return is (R1)), O
The FF data is (R5). On the other hand, control data for the motor (Ml) when constant speed control is not performed is similarly output as a combination of a forward/reverse signal (F/R) and a drive signal (D/S). For example, the control data for normal rotation flaking at the time of return is (F D ), and the control data for regenerative braking at the time of return is (If''S). It is generated mainly by the fall (or rise) of the encoder pulse corresponding to the scan motor. The time (FG) since the previous FC interrupt is calculated at C=D, the difference (Δl-'G) from the set value (1'Go) is calculated at step σ, and the difference (Δl-'G) from the set value (1'Go) is calculated at step C. Determine whether or not there is a TON correction request. 'l' The ON correction request is set at the speed of the stationary system (1) or the set reference speed (FGo in terms of the time interval of the encoder noculus), then the scan ends. 1 until
If it is set to “NO”, it moves to the step entrance, but if it is “YESJ”, it moves to the step CI■ (Δ+′G>
0). "YIS" is because the pulse interval (FG) is larger than the set value (FGo) and the scanning speed of the scanning system is slow, so the predetermined value (1 in the non-executive example) is set in step r. Add to standard time (TON). If the above step opening] is j'-NOJ, on the contrary, the scanning speed is fast, so a predetermined value is subtracted from the reference time (1" ON) in step C. Next, in step C, (1ΔI・Determine whether Gl≦+< ). (Kl is a constant that determines the allowable range of the difference (ΔFG) between the measured value (FC,) of the encoder pulse interval and the set value (FGo), and (1Δt; 'cl) or exceeds the allowable range, the determination is "NO" and step [D
Determine whether (∆FG>O) in the same way as step [step port]], and if it is JYESJ, drive in step [■, set the main motors (1 to 11) to full on, and step C lower down]. Outputs ON data and returns to the main routine. If step loco is "NO", set step C to full off, and turn drive off with step
Output the F data and return to the main routine. On the other hand, if the step port is determined to be YESJ, the step C child step is determined to be (ΔFG<O) and 1”N
If it is OJ, move to C complete], and then change the -r ON correction request to °゛1''' in step C if it is YESJ, then move to (E = engineering). When the speed of the scanning system is lower than FGo, the TON correction request is set to 1.
Figure 11 shows the subroutine (HOME). This is to reverse the main motor (Ml) and move the scanning system (the moon to the home position) if the scanning system (1) is not in the home position at the start of scanning. This is a subroutine that returns to John. In other words, at step 0, Baum switch (SW-1-1)
If it is "No", the scanning system (1)
QjAlthough it has returned to the home position, it returns to the main routine immediately. [If YESJ, the lever scanning system (1) is far away from the home position, so first, in step 0, the control data is set as (RD) to drive the motor (Ml) in reverse, and in step 2, the data for constant speed control is set as (RD). Set (FGo) + (ToN) + (A).
) and (R5), the subroutine (FGWAIT) is executed at step 0, and the constant speed side E is executed. Here, in step 0, turn on the scanning system (1) or the home switch (S'W-I-1), that is, after confirming that the scanning system (1) has returned to the home position, go to step Execute the interrupt prohibition routine (+vtCOFF), turn off the constant speed control, set the stop timer at step @, and proceed to the stop operation (fixed position control). That is, in step 0, the ff1l punishment l data is set to (L(I)), and the motor (Ml) is driven in normal rotation, and in step [phase], the end of the stop timer is waited for. The reason why the motor (Ml) is rotated in the forward direction is to cancel the reverse speed at the time of return. After the stop timer expires, the scan motor (Ml) is stopped by setting the control data (t's) in step O, and the process returns to the main routine. The subroutine (FGWAIT), as shown in Fig. 12, is for permitting interrupts for constant speed control.
After waiting for the falling input of the encoder pulse at step O, the TON correction request is set to "0", interrupt is enabled at step O, and the main routine is decided. The subroutine (MCOFF) is for terminating the constant speed open side j as shown in Fig. 13. After prohibiting interrupts in step [phase], control data is inputted in step [phase].
R5), the motor (Ml) is stopped and the process returns to the main routine. FIG. 14 shows the subroutine (SCAN:A). (SCAN:A) is the actual copy scan (SCAN2B)
) is a pre-scan execution routine that is performed prior to copy scan (S CAN: B), in which data is set for the motor on time (MTON) used in the subsequent copy scan (S CAN: B), and the timer value Tt for registration timing is set. ' or is set. First, in step [phase], (FD) is set in the control data to drive the motor (Ml) in normal rotation. This full-power forward rotation drive continues until the first encoder pulse input ball enters, helping the scanning system (1) to stand up. Then, the drive ON data (1 (D)) is stored in the RAM area of the microcomputer (3), and the drive OF
(FS) is set as F data. Next, in step 0, initial data is set in the braking delay counter (TM) upon return. Next, in step O, constant speed control data (FGo), (TON),
Set (A). At the same time, in step [phase], the counter correction value calculated from the scan size in the copy scan (SCAN:13) is set as (CT). this is,
The preliminary scan (SCAN:A,) is set to the minimum scan size and is usually larger than the actual copy scan L (SCAN:A,).
AN: Since it is shorter than B) and the braking start timing changes depending on the scan size, the preliminary scan (
This is to correct the counter measurement value at the return after SCAN:A). Next, in step (2), the subroutine (FGWAIT) is processed, the first input of the encoder pulse is awaited, and constant speed control is started. Then, at step [phase], wait until the 2-immer switch (SW-1") or the scanning system (1) is turned on, and when it is confirmed that it is turned on, step [
Start the counter at step [phase] and wait for the brake switch (SW-13) to be turned on at step [phase]. When the playback switch (SW-+3) is turned on, the counter value at that time is set to the timer switch (step [phase]).
distance l1 between sw-■) and brake switch (SW-B)
It is saved in the register as lIl-LTB and the counter is set to the preliminary scan size in step (2). The counter value set here is the brake switch (
, 5W-B) to the preliminary scan position. Then, wait at step [phase] for this counter to finish, and when it finishes, step @ and start the subroutine (MO
)FF) and disables interrupts. And motor +V corrected during preliminary scan (SCAN: A)
The on-base thread time 'I' ON (calculated at step C=〒)) of h is saved in the register (1"ON R) in step @, and the LTB saved in the register in the step [phase] is saved in step @. Based on the timer value -1-
t' is calculated by the following formula. 1-ε=1-TB-LTB. The timer value 1”E′ calculated here is (SCAN:B)
It is used to determine the registration timing. FIG. 15 shows the subroutine (SCAN:B). (SCAN:B) is the preliminary scan (SCAN:A)
This is a copy scan execution routine that is performed after. First, in step [phase], preliminary scan (SC; AN:
Similarly to step [phase] of A), the motor (Ml) is driven in normal rotation and the drive ON-OFF data is set, and in step O, the braking delay counter (TM) at the time of return is corrected. In other words, the speed control distance (C) and the constant set value (C) measured at the time of return as described below
K), and add the difference to the data (TM) set last time (preliminary scan). Next, in step O, a counter is cleared in order to measure the next return braking timing. At the same time, in step 0, the constant speed control data (F
Go), (A) is restored, and in step O, the basic time (1'' found by the preliminary scan (5CAN: A))
ON). Next, in step O, the subroutine (FGWA I T
) is processed, and constant speed control is started. Then, wait for the timer switch (SW-T) to be turned on in step ①, and when the timer switch (SW-T) is turned on, the timer value ゛r calculated by the preliminary scan (SCAN:A) is
[' timer is started at step O. and,
At step O, determine whether the brake switch (SW-B) is turned on, and if YES, set the scan size on the counter at step [phase].This scan size is set at step O of (SCAN:A) The scan size is based on the paper size.Next, step [Phase]
to determine the end of the timer '17t', and if YESj, step O and output a signal to turn on the timing roller (107) to the outside (signal 1 to turn off the timing roller) i<ON to "0'" At step O, the timer TTRON, which determines the timing roller on time, is started at step O.Then, at step O, the end of timer rT[++i is determined.If YES, the timing roller (107) is turned off at step O. Step 2 determines the end of the counter, and if ``NO'', the process returns to step @ and repeats the loop; if ``YESJ'', the subroutine (MCOFF) is processed at step O, and the scan system 41 is ended. Figure 16 shows the subroutine (RIi TU RN). First, in step [phase], set (RD) to the control data and drive the motor (M+) in reverse at full power, and in step O, during scanning. At the same time, in step 0, the main motor check routine ((j-IECK) described below is processed to correct the rotation speed of the main morph (M2), and to check if there is any abnormality. Since the scanning system (1) and the photoreceptor cannot be synchronized, the scan motor (MQ) is stopped for one moment.Then, in step @, the brake switch (SW-B) is switched to the scanning system (1). Wait for it to turn on.This brake switch (
When SW-13) is turned on, a braking delay counter (-1”M) is started at step @, and step [
Wait for its completion. The set value of this counter (TM) is the value of the initial data set in step (2) when returning after the preliminary scan, and the value corrected in step (2) when returning after the subsequent copy scan. When the counter (TM) ends, in step [phase], set (FS) to the control data and apply a regenerative brake to the scan motor (Ml), and in step @, set the predetermined value (TC) in the counter. Wait for the end of the count in step [phase]. At the end of the count, (F I) is set in the control data in step [phase], and the forward rotation brake is applied to the motor (Ml). With this, when the rotation speed of the motor (Ml) (that is, the scanning system) is decelerated to below the return speed or a predetermined speed, this is detected in step [phase], and in step O, the reverse constant speed control data is is set, and constant speed control of reverse rotation is performed. That is,
In step O, the control data is set to (1 (1)) to reverse the motor (Ml), and the drive ON data p (1 (D) and drive OFF data (KS) are set. subroutine (FGWAI
T) and performs constant speed control. Next, set the counter in step O, and step 0
The home switch (S'W-1-f) is the scanning system (1)
Count the number of encoder pulses until it is turned on,
The count number (CT) is saved in step @. The count number (cr) exactly corresponds to the distance traveled by the scanning system (1) during constant speed control, and is used at step 0 in the next copy scan to determine the braking timing for the next return. used for calculations. Then, in step O, a subroutine (MCOFF) is processed, interrupts are prohibited, and constant speed control is terminated. Then, position control, i.e. nGJN self-sufficiency (1-IOME)
The same control as step @ ~ [phase] is performed, and the scanning system (moon) stops at the home position. Figure 17 shows the main motor (Mz) check routine (
(j (IiCK). First, in step [phase], the pulse time interval (F
G/), and in step O, the pulse time interval (FG/) is measured.
) is within a certain range from the reference value (FG'o). If it is determined as YES, this routine (CHECK) ends and returns to the main routine.
If it is determined that j'-NOj, (FG'
-FC' o-ΔFG/ ) positive/negative (Δl・c'>
o) is determined. 1YEsJ If the rotation rate of the main motor (Mz) is low, check the motor level (step O), and if it is at the highest level (15) that is allowable for correction, a trouble signal will be issued at step O, and correction will be made. If it is within the allowable range, increment the level with step, and increase the rotation speed of the main motor (Mz) with step @.
Return to main routine. On the other hand, if it is determined as "1 NO" in step O, the rotation speed of the main motor (Mz) is good, and the motor level is checked in step [phase], and if the correction a1: is the lowest level (0) of A trouble signal is issued in step O, and if it is within the correction allowable range, the level is decremented in step [phase], and the rotation speed of the main motor (Mz) is decreased in step O. Also, if a trouble signal is output outside the correction tolerance range,
In step O, set (FS) to the control value and apply regenerative braking to the scan motor (+vft).In step O, wait until the encoder pulse interval (FG) becomes below a certain level, and when it becomes below a certain level. Step O
(LL) N-OF Set (KS) to the data and stop the scan motor (Ml). ” - At the time of return of the embodiment described above, the setting value (j') of the braking delay counter (TM) that determines the braking timing is
fvln-1-z, n number of scans) is measured during constant speed control of the previous return (step @-@) Data indicating the moving distance during constant speed control of scanning system (1) (
C'l'n) to successively correct the optimum braking timing.
↓I will do it (Step O). Expressed as a control equation, 1
'M +1 + 1 ='l'M n +cTn -C
In other words, when (CTn < CK), the braking timing is earlier, so the next count setting value (TM n +r) is set to the previous count setting value (Ta).
n n ). On the contrary, (CI'n >C
K), the braking timing is delayed, so the next count setting value (1"Mn-1-t) is corrected to be smaller than the previous count setting value (TMn). In other words, in either case Also, the next count setting value (TMn
H−+ ) to a constant value (71″) that is (σI″n=CK)
M). In the following embodiments, the registration timing is corrected at the time of shipment from the factory or during maintenance by service personnel. That is, while making a test copy, the position of the timer switch (SW-T) is adjusted so that the leading edge of the copy paper coincides with the leading edge of one image on the photoreceptor. After being adjusted in this way, the timer value T is set for each preliminary scan prior to copying.
Since t' is calculated and used in a timer that determines the registration timing during actual scanning, the timing roller is always turned on or off according to the latest timer value, so that the leading edge of the temporary sheet and the image on the photoreceptor accurately match. As described in detail in ``Effects'' (2), the present invention includes a scanning means for scanning a document at a speed corresponding to the copying magnification, and a method for projecting and forming an image of the scanned blood document onto a photoreceptor that is driven to rotate at a constant speed. an image forming means for transferring the image formed on the photoreceptor onto copy paper; and a conveying means for feeding the copy paper from a common standby position to the transfer means for any copying magnification. a variable magnification copying machine comprising: a detection means installed in a scanning path of the scanning means so that its position can be adjusted; a means for measuring an adjusted movement amount of the source means; a timer means having a timer value determined by the timer value; and a control system for activating the timer means by detecting the detection means or the scanning means and for activating the conveyance means by time-up of the timer means! +llI means, it is possible to easily adjust the registration timing for moving the conveying means by 1", and the detection means for operating the timer for multiple copying magnifications is only 1".
It has the advantage that only one person is required. Further, if the adjustment movement amount of the detection means is measured by measuring the distance between the detection means and the second detection means, the measurement can be easily performed. Here, since the position of the second detection means is arbitrary, it can also be used as a detection means used for other controls.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the basic idea of the present invention, Figure 2 is a schematic sectional view of an electrophotographic copier to which the present invention is applied, Figure 3 is a perspective view of the scanning system, and Figure 4. 5 is a block diagram of the control means, FIG. 5 is a motor control circuit diagram, FIG. 6 is a graph showing speed changes during scanning and return of the scanning system, and FIG. 7 is a pulse waveform diagram for explaining constant speed control. Figures 8 through 17 are flowcharts of the control means. (1) Scanning system, (2) Encoder, (3) Microcomputer, (4) Driver circuit,
(5)...Waveform shaping circuit, (6)...Reference oscillation circuit, (M+)...Scan motor (SW-J-1)
... Home switch, (SVV-B)... Brake switch, (SW-T), Timer switch, (S
CANNA)... Preliminary scan, (2B to SCA)... Copy scan, (Tt')... Timer. Patent applicant Minolta Camera Co., Ltd. Figure 1 Figure 2 Figure 11 Figure 12 Figure 13

Claims (1)

[Claims] 1. A scanning means for scanning an original at a speed corresponding to the copying magnification, and a scanning means for projecting and imaging the scanned original 4'1% (gl) onto a photoreceptor which is rotated at a constant speed. A variable image forming apparatus having an image means, a transfer means for transferring the image formed on the photoreceptor onto copy paper, and a conveyance means for feeding the copy paper from a common standby position toward the transfer means for any copying magnification. In a double copying machine, a detection means is installed in a scanning path of a scanning means so that its position can be adjusted; a means for measuring an adjustment movement amount of the detection means; and a timer means having a timer value associated with the adjustment movement amount. and a control means for activating the timer means when the detection means detects the scanning means and for activating the conveying means when the timer means times up, and controlling the timer of the timer means by adjusting the position of the detection means. A variable speed copying machine, characterized in that the timing at which the conveying means is actuated is adjusted by changing a value. 2. A second detection unit in which the movement amount measuring means is installed vertically with the detecting means. and wherein the adjusting movement amount is measured as a difference between a reference distance and a distance between the detecting means and the second detecting means. Double copying machine.