JPS592026A - Variable power image forming device - Google Patents

Abstract

PURPOSE:To enable the formation of an original image at an exact magnification by returning an optical member once to a reference position after plural times of operations at changed magnifications are performed then moving the optical member. CONSTITUTION:When a motor 29 is run forward and a lens is kept moved in an arrow A direction, a microswitch 45 emits a signal upon lapse of certain time. The signal indicates the arrival of the lens at a reference position but in some cases the lens stops in the position deviated from said reference position. A torque limiter 25 is provided in the route where the driving power is transmitted to a lens base 16, in order to correct said deviation. The torque limiter is designed to continue the operation of the motor 29 up to the point of the time slightly after the point of the time when the switch 45 forms the signal and to de-energize the motor 29 after a bearing 18 is held pressed positively to a stopper 44 by such continued operation, that is, after the lens is correctly stopped and held in the reference position.

Description

[Detailed description of the invention] The present invention relates to a variable magnification image forming apparatus.

In a variable magnification image forming device, such as a variable magnification electrophotographic abdominal camera,
By changing the position of optical members such as lenses and/or mirrors constituting the optical system that projects the original image onto the photosensitive surface, changing the magnification (9) is 4V i
It is nl. It is conceivable to control the amount of movement of the C member (as shown above) by counting the pulses generated by the pulse train generating means when changing the magnification, but if the predetermined number of pulses is If the driving means is stopped and the optical member stops due to the inertia of the optical member from its normal position corresponding to the selected magnification, or if the means for driving Q is rotated. Due to stuffiness, etc., the relationship between the number of pulses and the rotation speed of the driving means may deviate from the desired relationship, and the optical phase may deviate from the normal position and stop. .Thus, as the magnification changing operation is repeated many times, the above deviation accumulates.
L.

It may become impossible to form an original image at the required magnification on the photosensitive surface, or
The focus state of the image goes out of the permissible range, and you feel relaxed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable magnification image forming apparatus which solves the above-mentioned disadvantages.

The present invention will be described in detail with reference to the drawings below.

FIG. 1 is an explanatory diagram of a variable magnification electrophotographic copying machine to which the present invention can be applied. In the figure, reference numeral 1 denotes a photosensitive drum having an electrophotographic photosensitive member on its circumferential surface, which rotates in the direction of the arrow. As the drum 1 rotates, it is first uniformly charged by a corona discharger 2, and then transferred to an optical system to be described later via a slit 3.
The optical image at a selected magnification is slit exposed. As a result, the electrostatic latent image formed on the drum 1 is developed by the developing device 4, and a toner image is obtained. This toner image is then transferred under the action of a transfer corona discharger 5 to a transfer paper P that is conveyed in the direction of the arrow. This transfer paper P is then sent to a fixing device 6, and the transferred toner image is fixed on the paper P. on the other hand,
After the transfer, the drum 1 is cleaned by a cleaning device 7 and used again for the image forming process.

The original is placed on a fixed transparent original table 8. The original O is illuminated by a lamp 9, and the light reflected from the original is sequentially reflected by mirrors 10, 11, and 12, and enters a zoom lens 13. The imaging light beam from the document exiting the zoom lens 13 is reflected by the mirror 14 and enters the photosensitive drum l as described above, forming an optical image of the document O at a selected magnification. The lens 13 is at the solid line position 1 & 13 in the figure. When the l/lens 13 is moved to the 132nd position, an m1 times image of the document is formed on the drum 1, and when the l/lens 13 is moved to the 132nd position, an m2 times image is formed on the drum 1.
When moved into position, an m3 magnification image is formed. town here)
m2) Set to ff13. For convenience, m,=
Although the present invention will be described as No. 1, the present invention can also be applied to an apparatus capable of copying an enlarged image of a document. Note that this is the reference position of the 134th lens 13.

When the position of the zoom lens 13 is changed as described later, zooming is performed in conjunction with this, and the lens focal length is changed to a value corresponding to the new lens position, in other words, a value corresponding to the selected copy magnification. Ru.

Here is the optical path length between the original and the lens! , and the sum of the optical path length 12 between the lens and the photoreceptor is /(J is constant), and the imaging magnification of the original image (i.e., the selected copying magnification) is m, and the focal length of the lens is f, then 11-box The position and focal length of the lens may be changed in accordance with the selected magnification m so that i, -m 1 m + 1 .

The apparatus shown in FIG. 1 is of an original scanning type. In order to scan the original, the mirror 10 is integrated with the lamp 9 in the direction of the arrow, and the circumferential speed of the drum 1 is multiplied by the reciprocal of the selected copying magnification, 17 m, in order to set the copying magnification in the same rotation direction of the drum to m. The mirrors 11 and 12 move in the direction of the arrow at a speed of 1/2° of the mirror 10 in order to keep the optical path length between the document and the lens constant. In this way, the original O is scanned and its image is placed on the drum 1.
slit exposure. When scanning of the original is completed, members 9~
12 moves backward and returns to their respective forward movement starting positions.

FIG. 2 shows the movement and zooming mechanism of the lens 13.

In the figure, 15 is a lens barrel housing the zoom lens 13. This lens barrel 15 is fixed to a lens stand 16. Slide bearings 17 and 18 are fixed to the lens stand 16, and these bearings 17 and 1B are slidably fitted into an iα linear guide rail 19 fixed to the substrate 20. Therefore, the lens stand 16 on which the lens 13 is mounted can reciprocate under the guidance of the guide rail 19 in directions parallel to the guide rail (direction A, direction B). Note that the direction of the rail 19 and therefore the moving direction of the lens 13 are inclined with respect to the optical axis of the lens 13, but this is because the side edge of the document is aligned with the side edge reference position of the document table 8 during copying at any magnification. This is to form an image of the document side edge onto the reference position of the photoreceptor side edge. Therefore, when copying at any magnification, the center of the document is placed at the center of the document table, and the image of the center of the document is placed at the center of the photoreceptor K&'? In a copying machine such as the one shown in FIG.

Both ends 21' of the wire 21 are attached to the lens stand 16.

21" is locked. The wire 21 is hung on pulleys 22 and 23 that are rotatably supported by shafts 22' and 23' fixed to the base plate 20, and is driven between the pulleys 22 and 23. The driving pulley 24 is wound around a pulley 24 several times.
It is attached to the support 26 via 25. This shaft 26
There is a worm wheel.

27 is fixed, and this...worm wheel 27
The motor 29 is meshed with a wino gear 28 fixed to an output shaft 30 of the motor 29. When the motor 29 rotates forward, the worm gear 28 and the worm wheel 27 rotate the shaft 26.
rotates clockwise, and when the torque limiter 25 fixedly connects the shaft 26 and the pulley 24, this pulley 24 rotates clockwise, so the lens stand 16 on which the lens 13 is mounted is indexed to the wire 21. and moves in the direction of arrow A.

Similarly, when the motor 29 reverses, the pulley 24 is rotated counterclockwise in the H1 direction, and the lens stand 16 is guided by the wire 21 and moved in the direction of arrow B.

A disc 31 as shown in FIG. 3 is fixed to the output shaft 30 of the motor 29. Therefore, this disk 31 is
As is clear from the above, when the shaft 26 and the pulley 24 are fixedly connected by the torque limiter A25, the disk 31 rotates in synchronization with the lens 1.
It rotates in synchronization with the movement of the lens stand 16 on which the lens 3 is mounted.

As shown in FIG. 3, the disc 31 is an opaque disc 31' provided with a large number of light-transmitting strips 31" of equal width at equal intervals. 32 is a photocoupler fixed to the substrate 20. The light-emitting element section 32' and the light-receiving element section 3f are arranged with the slit forming area of the disk 31 in between.Therefore, as the disk 31 rotates due to the operation of the motor 29, The light emitted from the light emitting element section 32' passes through the slit 3.
1", the light-receiving element section 3f periodically generates electric pulses.The rotation angle of the shaft 26 that rotates during one pulse period of this pulse train is the same at any time, so the above-mentioned l The amount of movement of the lens stand 16 on which the lens 13 is mounted with the pulse period f is the same at any time.When the motor 29 is driven during the magnification change operation, the lens 13 starts to move as described above, and The above-mentioned pulse train starts to be generated synchronously, and as described later, the number of pulses is counted, and when the number of pulses corresponding to the selected magnification is counted, the motor 29 is deenergized and the lens is turned off. Therefore, the lens 13 moves by a distance corresponding to the selected magnification.

As described above, the lens 13 is a zoom lens, and in the embodiment shown in FIG. 2, zooming of the lens is performed in conjunction with the movement of the lens. FIJ, lens mirror fi'i
A cam hole 15' is provided in f 15, and a bin 33 fixed to a focal length changing lens holding tube movably provided in the lens barrel 15 in the optical axis direction is provided in the cam hole 15'. is provided with an engaging protrusion. A zoom ring 34 is attached to the lens barrel 15 so that it does not move relative to the lens barrel 15 in the optical axis direction, but can rotate about the optical axis X. The zoom ring 34 is provided with a long hole 34'.
The bottle 33 is engaged with this elongated hole 34'.

Therefore, when the zoom ring 34 is rotated, the bin 33 moves along the cam hole 15', and thereby the lens barrel 1
Since the spacing between a given lens element within lens 5 changes, the focal length of lens 13 also changes.

The mechanism for rotating the zoom ring 34 is as follows.

That is, the zoom f:A34 is wound with a twister 35 one to several times. 36 is a wire support member slidably attached to the lens stand 16, and the wire 35
One end 55' is locked to one end of the support member 36, and the other end 35'' of the wire 35 is connected to the other end of the support member 36 via a tension spring 37 for preventing loosening. A linear guide rod 38 extending in a direction perpendicular to the optical axis She is almost cumming in the middle of the day.

Therefore, the wire support member 936 moves relative to the lens stand 16 in a direction perpendicular to the original axis X, and this movement drives the wire 35, so that the zoom ring 34 rotates. Here, a cam follower 41 is fixed to the wire support member 36, and this follower 414-1 is provided on a cam plate 43 fixed to the substrate 20 and is long in a direction inclined with respect to the lens movement direction. It is engaged with the cam groove 42 [2].

Therefore, if the lens stand 16 on which the lens 1:3 is mounted is moved as described above, the wire support section can be moved under the restrictions of 42. For the 36i□-t lens stand 16, the above
Relative contact! Since I+, Sushi, and υ Zoono and Current 34 rotate, the focal length of the lens 13 is changed. ``As you can see from the book, the amount of lens movement and lens zooming■'
a t, -1, corresponds. and cam 15', 42
The shape and installation direction of -Lens position and focal point l1llj
The settings are made so that the three equations described above hold true during V.

Now, 4.4. This is a stopper fixed to the iI′1 substrate 20.

In FIG. 2, this stopper 44 is provided at one end of the lens movement path. Then, when the lens stand 16 moves in the direction of arrow A and reaches its movement end position 1r1', the side surface 18' of the bearing 18 mentioned above is moved to the side surface 44' of the stopper 44.
, and the further movement of the lens base 1G in the direction indicated by the arrow q) is ejected. The position of the lens stand [6] which is stopped with the bearing 18 of the lens stand 16 in contact with the stopper 44 as described above is the reference position of this lens stand 16, and J1
The position of the lens 13 in this state is iff (first
Position 134 in the figure) is the reference position of the lens 13 in one row.

A microswitch 45 is fixed to the stopper 44, and when the bearing 18 contacts the stopper 44, the side surface 1B' of the bearing 18 contacts the actuator of the microswitch 45. . In other words, when the lens stand 16 comes to the reference position, the lens 13
When the microswitch 45 reaches the reference position 134, the microswitch 45
gives a signal.

As described above, when the motor 29 is rotated in the forward direction to continue moving the lens in the direction indicated by the arrow, the microswitch 45 issues a signal after a certain period of time has elapsed. This signal is a signal indicating that the lens 13 has reached the reference position as described above, but if the motor 29 is deenergized and the driving of the lens stand 16 is stopped at the same time as this signal is generated, the lens 13 It is possible for the motor to stop at a position deviated from the reference position 13. This may be due to an error in the mounting position of the switch 45, an error in the activation timing of the switch 45, or a reaction to the collision between the bearing 1B and the stopper 44, causing the base 1
This is because 6 may be displaced in the B direction. In any case, the lens 13 is at the reference position 13.
When the lens 13 is moved from this position a distance corresponding to the number of pulses corresponding to the selected magnification, the new lens position will be the position 13.ttt corresponding to the selected magnification. or 13. Otherwise, the VM"f object with the required magnification cannot be obtained. Therefore, in the embodiment shown in FIG.
, and the operation of the motor 29 (L-continues) until a moment after the microswitch 45 forms the signal, thereby ensuring that the bearing 18 is firmly pressed against the stop 44 (i.e. with respect to the lens 13). position 13
4), the motor 29 is deenergized. In addition to the switch 45 shown in the illustrated example, as a position detecting means for the 1/lens, it is also possible to use a device in which a magnet is attached to one of the lens stand 16 and the stopper 44, and a Hall element is attached to the other. The signal generated by the Hall element when facing each other can be used in the same way as the signal from the microswitch 45.

Fig. 4 shows an example of a torque limiter. In FIG. 4, a shaft 26 (d) to which a worm wheel 27 is fixed is rotatably supported by bearings 46 and 47 fixed to the substrate 20.A flange 26' is integrally attached to this shaft 26. A perforated disk 48 is fitted through the shaft 26Kf.The base of the pulley 24, the shaft 26, and the flange 2
6', disk 48o) rl [K is spacer 49, 50.5
1 is interposed.

A compression spring 53 is interposed between the disk 4 and another perforated disk 52 loosely fitted onto the shaft 26. A nut 54 is screwed onto a screw provided on the shaft 26 to receive the disc 52. By adjusting the nut 54, the pressing force applied by the spring 53 to the disc 48 can be adjusted.

In any case, the elastic pressing force of the spring 53 brings the disc 48 and the spacer 51 into contact, the spacer 51 and the base of the pulley 24, the base of the pulley 24 and the spacer 50, and the spacer 50 and the 7 flange 26'. As long as the wire 21 is not subjected to a load exceeding a predetermined value, the shaft 26 and pulley 2
4 are connected to the same>52, and when the wheel 27 is driven to rotate, the pulley 24 also rotates integrally with the shaft 26, and the lens is moved in the A direction and the B direction as described above. However, when the lens mount 16 is rotated eastward with the bearing 18 of the lens mount 16 in contact with the stopper 44 as described above, that is, when the lens holder 16 is further moved in the direction of the arrow, the wire 21 Because the applied load exceeds the specified value (1) above [
J spacers 49, 50, 5] and the shaft 26, flange 26', and disk 48 that are in contact with each other, slipping occurs, and the worm wheel 27 is rotated when the pulley 24ij is in a state where it has stopped rotating. It only rotates 1H1J integrally with 26. In other words, what about motor 29? (2 turns. Thus, lens 1
Accurate positioning to the reference position It134 of 3 is maintained! d: It will be done.

In addition, if the correct positioning of the lens position detection means and the pressure line operation timing are guaranteed, and if the stand 16 is torn, the torque limiter is omitted, and the torque limiter is immediately activated when the microswitch 45 issues a signal. The transmission of the driving force to the lens stand 16 may be stopped.

Next, the operation of the above mechanism will be explained. A microcomputer is used for operation control. That is, as shown in FIG. 5, the one-chip microcomputer MO includes a copy key SWa for instructing the copying machine to perform a copy operation, and a copy magnification ml.
Confidence key SWI to command, copy magnification m, specify m
7x key SW2, m3x key S to specify copy magnification ms
A drive circuit D to which signals from W3, the pulse train generator 32, and the lens position detector 45 are applied, and rotates the motor 29 in the normal direction.
It outputs a signal (2) that energizes the drive circuit A, a signal (2) that energizes the drive circuit DB that reverses the motor 29, and a heat signal (3) that causes the copying machine to perform a copying operation. When the signal ■ is at H level, the circuit DA is energized and the lens 13 moves in the direction of arrow A in FIG. Also, when the signal ■ is at H level, the circuit DE is energized, and the lens 13
q@2 Move in the direction of arrow B in the diagram. When the signals ■ and ■ are at the b level, the circuits DA and J)B are not energized and the lens 13
has stopped. In addition, the output of the signal (■) causes the driving means of the photosensitive drum 1 to the driving means of the chargers 2 and 5, the driving means of the developing device 4, the driving means of the fixing device 6, the driving means of the rung 9, and the driving means of the mirror 10+1lt12. The drive means, the paper P conveyance drive means ℃ (the above opening drive means are collectively referred to as CD) are energized according to a predetermined sequence, and the first
The copying process explained in the figure is carried out to form a copy image from the original O onto the paper P. As the sequence of the copying process in which each of the driving means OD operates can be a known one, the description thereof will be omitted in this specification to avoid complexity.

In addition, the microcomputer MO has a Noculus train generator 32.
Counter (TNI) that counts the number of pulses generated by
) function and a counter (TN2) function that counts the number of times the lens is moved to change the magnification.

As shown in FIG. 7, the lens moves from the reference position 134 to the position 13. when copying 1113 times. The pulse train generator 32 generates 27 pulses to move at t, generates 22 pulses to move from position 133 to position 132 when copying m2 times, and moves from position 13 . From m1 times y y, t.

Hour position 13. It is assumed that 23 pulses are generated to move to .

Now, what is shown in FIG. 6(A) #(B) 1 (0) is a flowchart of the control software by the microcomputer MO. In FIG. 6(A), when the power is connected to the copying machine (power ON), whether the lens 13 is located at the reference position 134 or not depends on whether the microswitch 45 is forming a signal or not. If it is Yes, it will jump to Step S4, but if it is NO
In this case, the signal ■ is set to H level and the lens 13 is moved in the direction of arrow A (step S).

When it is determined by the signal from the microswitch 45 that the lens 13 has reached the reference position 134 (step SS), the counter TN2 is first cleared (step S), and then the counter TNI is set to 24 count pulses. (Step Ss). This is the number of pulses 24 from the time when the bearing acts on the micro switch 45.
This is to continue driving the motor 29 in the forward direction until a later point in time, thereby accurately holding the 1/lens 13 at the reference position 134 as described above. (Accordingly, P4 does not need to be as large as a value, but is selected to be as small as possible within the range that allows accurate positioning of the lens 13 at position 8134.) For this reason, after step S, a pulse train is sent to the counter TNl. It is determined whether or not a pulse input from the generator 32 is received (step S6), and each time a pulse is input to the counter TNl, the counter T
Decrement NI and go (Stella 1S).

In this way, it is determined whether TN1:Q has been reached, that is, it is determined whether the time corresponding to the number of 24 pulses has elapsed since the microswitch 45 issued the signal.
), if Yes, the signal ■ is set to L level to stop driving the motor 29 (step 8112), and then the counter TN2 is set to 1 (step S1°). This counter TN2 indicates how many times the lens 13 is at position 13 or 13.
2 or 13. (In other words, each position when the copying process is performed)
The number of times the mouth is positioned is α (for example, 5 times, but the number of times depends on the desired imaging magnification accuracy and the positioning error in each of the above positions, etc.). Once the selected magnification is reached, the lens 13 is returned to the single reference position 134 and the position 13. or 13. or 133. Therefore, in the embodiment, this counter TN2 corresponds to the lens 1.
3 in the above position 13. Or, before moving to 1 or 133, the movement is counted as one time. In any case, after step 81G, the lens 13 is moved from the reference position 134 to the position 13. Counting pulses required to move to & (, P, + p, 10 p
, ) are set (step 8+1). Next, the signal ■ is set to H level and the lens 13 starts moving from the position 134 in the direction of arrow B (step 81!). Then, it is determined whether the lens is in position 13 or not (Step 813)% Next, pulse generator 32 is applied to counter TN1.
Step &! 4),
If there is this human power, the counter TNI is decremented (step S4), and then 1...' The number of pulses set by the counter TNI (P, + P2 + I°
3) are all counted (step S).
, 6).

When it is determined that TNI = O in this step 811,
The lens is 13. Since the position has been reached, the signal ■ is then set to the L level, the motor 29 is stopped, and the lens movement is stopped (step S7). Thus, compound′! When the power is turned on to the machine, the lens 13 is first positioned at the reference position 11134 1a, and from that position it is moved to the position W13. I
tc movement is stopped. Therefore, next press the copy key SWa to O.
If N is selected, an accurate same-size image of the original can be copied. (Incidentally, the highest frequency of reconnaissance is the same size four copies.) Now, the operator presses the keys SWI, Si2, Si.
2. Turn on the desired magnification designation key. Therefore, the microcomputer MO next determines in step SI8 whether or not the magnification designation key is manually available, and if No, the process proceeds to step S, which will be described later. However, in the case of Ye8, go to step S. , the current position of the lens is selected times −
It is determined whether it is necessary to move the 0J lens to the position corresponding to the position corresponding to the designated key 16 (resultant force), in other words, to 1rt corresponding to the selected magnification, and if NOσ], the process returns to step S18. The presence or absence of the manual input of the magnification specifying key is determined again in steps S and 8, but at this time, the input information has already been determined and deleted, so the determination is No, and step S continues.

go to. In step S2°, it is determined whether or not the copy key SWa has been turned on. If YES, the above-mentioned copying step 82+ is carried out by the signal (2), but if NO, the process returns to step 5Ill. Therefore, next copy key SWa
S,...,S until you turn on or turn on the magnification specifying key.
,. The steps are repeated repeatedly.

On the other hand, if it is determined in step 310 that it is necessary to move the lens 13, the counter TN2 is incremented in step sty, and then it is determined whether the count number of this counter TN2 has reached (α+1) (step sty). S, 8).

If it is determined that TN2: (α+1), the lens has already been used α times for 13. or 13. Or, since the movement to the 133rd position is being performed, move to the ■ system shown in Figure 86 (0), return the lens 13 to the -f reference position 134, and from that position press the (#f rate digit designation key). Therefore, it is moved to the designated position.However, if No in step 82B, steps S and 4 in FIG. 6(B) are performed.
Move the lens to position 13. From 13. It is determined whether or not to move the lens to position 1113. If no, the lens is moved to position 1113. It is determined whether or not to move the lens from position 15□ to position 13. It is determined in step S26 whether or not to move from to 133. Step S24
y 5211 + S26 is a determination as to whether or not to move the lens in the direction. Then step 82
If Yes in step 4, the number of counted pulses is 23, and step S
! If Yes for Kuzu, count pulse I! I(Ps+Pt
) and, if Yes in step S26, the number of counted pulses p, respectively, are set in the counter TNI (step s
2□, s2゜+"!11)0 Next, the signal ■ is set to the H level and the lens 13 starts moving in the direction A from the position where it is currently located (step 83
0 ), step set ``Ty s! 11 ''9, step 331 + ``'at + '''33
r 834, and set the lens 13 to the counter TN.
Move the distance N corresponding to the number of pulses set in l. That is, the lens 13 is moved to a position corresponding to the magnification specified by the magnification specifying key and stopped. When this is completed, the program jumps to the location shown in FIG. 6(A).

On the other hand, if the result in step S26 is NO, the remaining case is to move the lens 13 in the B direction.

Then, use the Stetsuno 5311 to move the lens to position 13. From 13
Steps S, ), and N to determine whether to move to ° or not.

In this case, move the lens from position 133 to position 13. Step 536)% If the answer is No, it is required to move the lens from position R13s to position R132.
2 (step S3°). On the other hand, step S
If Yes in step sse, count pulse number P, and if Yes in step sse, count pulse l1i(p2+P3
) are respectively set in the counter TNl (step S31
eS3g). Next, in step 840, the signal (2) is set to H level, and the lens 13 starts moving in the direction of arrow B from its current position. ;t: PM S4
1 +S42 eS49° is executed to move the lens] 3 a distance corresponding to the number of pulses set in the above-mentioned curvature TNI. That is, the lens 13 is moved and stopped at a position corresponding to the magnification specified by the rate specification key.

When this is completed, the program jumps to the point ◯ in FIG. 6(A).

Next, step S2 in FIG. 6(A). If the result is Yell, the process moves to step 845 in FIG. Set the initial value l to TN2. Next, in step SSS, it is determined whether or not to move the lens to the 133rd position, and if NO, it is determined in step 86' whether or not to move the lens to the 137th position, and if NO, the lens is moved to the 132nd position. Step 5
At 11g, the n1 number pulse number (P!
＋P! +P3). On the other hand, step S
If Yes in step s4, if Yes in step s,
In steps S@61 and S57, counting pulses W1. P, , (P++Pt) are set respectively. Then, in step S, the signal ■ is set to the H level, and the lens 13 is moved from the reference position Iff 134 to the B-direction step≠seo ys61 +562A, and the lens 13 is set to the number of pulses set in the counter TNI. It is moved from the corresponding distance reference position 134. Tsuma υ
The lens 13 is moved from the reference position 134 to the position specified by the magnification specifying key and stopped. In the case where the magnification designation key is not turned on during the movement of the lens,
Step 811B and Step S. is repeated. Then, when the copy key SWO is turned on, the copying step S21 of forming a copy image at the selected magnification is actually performed seven ffti. If the magnification designation key is turned on somewhere else during the lens movement operation and is pressed 1, step S181811
1, the process moves to step S22, and the above-mentioned control is performed.

Note that in the above example, the lens is returned to its original position after multiple magnification change operations, but if you do not mind that it takes time to change the magnification each time, then the magnification change operation can be performed. Each time, the lens is returned to the reference position to ensure accurate positioning, and then moved to 1d corresponding to the selected magnification. For this purpose, for example, step S4 t SIO'rStt +S23 of the program flownayat described above is omitted (therefore, the function of counter TN2 is removed from the microcomputer Opu), and when YO2 is determined at step S1°, the function shown in FIG. It is sufficient if the connection is made to step S45 of (0).

Further, in the above example, the end of the lens moving path is set as the reference position of the lens, but the position between both ends of the lens moving path may be set as the reference position ]n. In this case, the stopper that stops the lens at its reference position should be moved in and out of the lens table moving path using a solenoid or the like. to lock it.

Furthermore, in the example of side 3, the reference position of the lens is set to eight positions other than the lens position used in the copying process, but the lens position used in the copying process may be set to the eighth position. For example, if lenses are arranged at 134 positions, a copy image of m4 times the size may be obtained.

In the above-mentioned embodiment, the magnification can be changed in 3 to 4 steps, but the present invention can also be applied to a copying machine capable of copying at the same number of magnifications. The present invention can also be applied to a device capable of changing the magnification in many steps, that is, a device capable of changing the magnification virtually steplessly1.Also, in the above embodiment, the pulse train is generated by a slit disk rotated by a motor. However, other clock pulse oscillators and the like can also be used. In this case, a pulse motor whose rotation is controlled by the clock pulse oscillator may be used as the motor 29.

Furthermore, in the embodiment described above, the movement and stopping of the lens is controlled by energizing and deenergizing the motor 29. However, a clutch is provided between the motor 29 and the worm gear 2B":;', and the energizing 1 of this clutch is controlled. The movement and stopping of the lens may be completely controlled depending on the stay.

Although a zoom lens was used as the lens in the above example, the present invention can also be applied to device a that uses a fixed focus lens. In that case, when changing the magnification, use Haragiri,
It is also necessary to change the total optical path length between the photosensitive surfaces, so the forward movement starting point iI'1 of mirror 10 or mirrors 11 and 12 must be changed.
1 or the position of the mirror 14 may be changed in accordance with the selected magnification. Thus, the present invention can be used to change the mirror position as described above with a quotient of 1/14.

Furthermore, the present invention provides a device that scans a document by moving the document table, or by moving the document using a document transport roller, a belt, etc., or a device that scans the document by moving the document table, or by condensing all 101 bXX images onto nine surfaces at once. M JJJ can also be used for a device u that emits red light.

The present invention is a digital copying machine that forms an original image on a COD or the like to form an electrical signal corresponding to the entire original image, and uses the electrical signal to form a desired image.

It can also be used for facsimile, etc.

In any case, according to the present invention, in a device that controls the movement of an optical member by applying pulses dI when changing the magnification, after at least a plurality of magnification changing operations have been performed, the yC member is moved at once. Since the optical member is moved after returning to the reference position, the number of pulses that is Nl and the position of the optical member that has been moved corresponding to the number of pulses are:
The selected magnification will be accurately correlated,
It is possible to form a 1 quintillion draft image with accurate magnification and focus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example of a "Machi variable magnification" Yamiko photocopying machine to which the present invention is applied, FIG. 2 is an explanatory diagram of an example of the lens moving mechanism of the device shown in FIG. 1, and FIG. 3 is a slit disc An explanatory diagram of an example of
FIG. 4 is an explanatory diagram of an example of a torque limiter, FIG. 5 is a block diagram of a control system according to an embodiment of the present invention, and FIG. 6 (A) F
(B) f (0) is a flowchart for explaining the software of the control system in FIG. 5, and FIG. 7 is a diagram for explaining the number of pulses for lens movement. 0 is the original, 1 is the photosensitive drum, 13 is the zoom lens, 15
is the lens barrel, 16 is the lens stand, 19 is the guide rail,
21 is a drive wire, 24 is a drive pulley, 25 is a torque limiter, 26 is a drive shaft, 27 is a worm wheel, 2B
is a worm gear, 29 is a motor, 31 is a slit disk,
32 is a photocoupler, 34 is a zoom ring, 44 is a stopper, and 45 is a microswitch. 111 people Canon Co., Ltd. Agent Gi Marushima Says: 9°:j ”:', 1. + 1 in sl

Claims (1)

[Claims] In a variable magnification image forming apparatus that changes the imaging magnification of the original image by changing the position of an optical member for forming an image of the original on a photosensitive surface, the apparatus includes a pulse train generating means and a pulse train generating means for changing the erroneous rate. means for controlling the amount of movement of the optical member by counting the pulses generated by the pulse train generating means;
For each magnification change operation, the magnification change operation is performed one or several times. Variable magnification image formation characterized by comprising means for moving the optical member to a desired position by once moving the optical member to a predetermined reference position and counting the number of pulses from the reference position. Device.