JPH06118514A - Lens position controller - Google Patents

Abstract

PURPOSE:To obtain a lens position controller which precisely positions a lens at a desired power position. CONSTITUTION:A detection plate which is formed by plural slits used for controlling the movement position of the lens and indicates fixed power is arranged along the movement direction of the lens and the slits of the detection plate are detected by a sensor 13; and a motor 6 for moving the lens along a movement path is driven by steps through a CPU 20 to position the lens at a position corresponding to inputted power. The CPU 20 moves the motor 6 for positioning the lens at the slits when the inputted power corresponds to the fixed power of each slit of the detection plate, but drives the motor 6 on the basis of a slit indicating close power as a target when not and then calculates the number of steps regarding the inputted power from remaining target slits to drives the motor 6 as many as the steps and then stop it, thus controlling the position of the lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens for projecting an original on a recording medium or a reading element (image reading element such as CCD), and changing the position of the lens to change the projection magnification. Regarding position control.

[0002]

2. Description of the Related Art In an image forming apparatus, an image reading apparatus, etc., an optical lens is used to project (image) an image of a document on a recording medium or an image reading element such as a CCD.
For example, in an image forming apparatus, a lens is arranged in the optical path between a document and a recording medium, that is, a photoconductor, and the lens projects an image of the document on the surface of the recording medium at a desired magnification.

When an image is projected on a photoconductor, a document placed at a predetermined position is illuminated with light, and reflected light from the document is guided by a mirror or the like in the lens arrangement direction. An optical path is formed that leads to the photosensitive member through the optical path. In this case, if the focal point of the fixed focus lens is f, the optical path length from the document to the lens is a, and the optical path length from the lens to the photoconductor is b, the image of the document is in the relationship of 1 / a + 1 / b = 1 / f. Will be imaged on the photoreceptor. Further, it is well known that the projected magnification m of the image at this time has a relationship of m = b / a.

Therefore, when using a fixed focus lens,
In order to change the magnification m variously, it is necessary to move the lens along the optical axis and appropriately set the optical path lengths of a and b. That is, if the magnification m is determined, the optical path lengths a and b are
It can be easily calculated from the above-described image formation formula and magnification formula, and the lens is moved along the optical axis so as to match the calculated optical path lengths of a and b. At this time, since it is not possible to set the optical path lengths of a and b to the obtained values by moving only the lens, it is necessary to move the placement position of the document and the position of the photoconductor, but Since the position and the position of the photoconductor are immovable, some of the mirrors arranged in the imaging optical path are moved to a predetermined position along the optical path.

On the other hand, if a zoom lens (lens whose focal length is variable) is used as the lens, various magnifications can be set while the optical path length a + b at the same magnification remains unchanged. In this case, it is only necessary to move the position of the lens to a predetermined position according to the magnification, and it is not necessary to move the lens and the like.

In order to make the magnification variable as described above, it is essential to move the lens. Therefore, in order to deal with a plurality of magnifications, a large number of sensors or the like are provided to detect the moving position of the lens and the lens is positioned at a predetermined magnification position. In this case, if the magnification is large, there is no space to install the sensor. For example, when it is desired to change the magnification at the stage of 1%, it becomes impossible to detect the position by the sensor and perform the positioning.

Therefore, conventionally, a stepping motor is used as a driving source for moving the lens, and the lens moving position is specified by counting the step pulse or the like for driving the stepping motor. This allows
It is designed so that the magnification can be changed in 1% steps.

[0008]

Conventionally, when a lens is moved to a predetermined magnification position by a stepping motor, the lens position is recognized by counting the number of steps, so that the stepping motor is prevented from stepping out. Need to consider. In other words, the position of the lens may not reach the predetermined magnification position due to step out.

Therefore, when the lens is moved, it is driven with reference to one reference position, for example, an equal magnification position, until a predetermined pulse is counted from that position. That is, the lens is returned to the same magnification position, and the stepping stepping motor is driven from that state according to the magnification to be set.

However, when the movement of the lens is controlled by one motor, it becomes impossible to perform accurate positioning due to a step out due to load or other problems.

It is an object of the present invention to provide an apparatus capable of accurately controlling the position of a multi-step magnification when moving a lens by using a step-driving motor as a drive source.

[0012]

In order to achieve the above-mentioned object, a lens position control device according to the present invention is provided with a lens provided so as to be movable along a moving path according to the magnification, and the lens having a predetermined magnification. A motor that is step-driven to move to a position, a detection plate that is arranged along the movement path of the lens and that has slits formed according to a plurality of fixed magnifications, a detection unit that detects the slits of the detection plate, any Input means for setting the magnification of, the lens at a position corresponding to an arbitrary magnification set by the input means, and when the set magnification is a magnification corresponding to the slit of the detection plate, At the slit detection position, the drive of the motor is stopped, and when the set magnification does not correspond to the slit of the detection plate, the slit detection position close to the set magnification is obtained, and the target is the target slit position. Tsu is moved until note position, to drive the position number of steps the motor until corresponding to the set magnification the position as a reference position, characterized by comprising a control means for stopping.

[0013]

Since the lens position control device of the present invention has the above-mentioned configuration, when the magnification arbitrarily set by the input means corresponds to one of a plurality of fixed magnifications previously formed on the detection plate. , The motor is driven up to the detection position of the slit corresponding to the fixed magnification, and the lens moves to that position, that is, the input set magnification and stops.

When the input arbitrary set magnification is different from the fixed magnification corresponding to the slit of the detection plate, the lens is first moved to the slit having a magnification close to the set magnification. Using this slit position as a reference position, the motor is driven by the number of steps corresponding to the set magnification to move the lens to the position corresponding to the set magnification.

Therefore, when the lens is moved to an arbitrary set magnification position, if it matches a preset fixed magnification, the lens can be moved to an accurate magnification position according to the slit detection of the detection plate corresponding to the fixed magnification. Even if the set magnification does not match the fixed magnification, the slit is detected close to the magnification position and step drive is performed using that position as a reference, so the lens is returned to the home position one after another and the predetermined number of steps is counted Positioning control can be performed more accurately and easily without the need for complicated control.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens position control device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a top view showing an optical system portion of an image forming apparatus equipped with a lens moving mechanism according to the present invention, particularly a copying apparatus. In the figure, the main body of the copying apparatus is an illuminating means 1 including a lamp and a reflecting plate for illuminating an original placed on an original placing table (transparent glass plate) not shown, and an image forming means for reflecting light from the original. And a mirror 4 for exposing the reflected light from the original document through the lens 3 to a drum-shaped photoreceptor which is a recording medium (not shown). Equipped with an optical system. The original placing table is provided on the optical system, and the photoconductor is rotatably provided under the optical system.

The lens 3 is a fixed focus lens, and the lens holder 3-1 is used to change the magnification variously.
Are provided so as to be movable along the two lens guides 5. A part of the wire 7 for transmitting the drive of the motor 6 is fixed to the lens holder 3-1, and the lens holder 3-1 is appropriately moved right and left along the lens guide 5 in the figure by the rotation of the motor 6. The motor 6 is step-driven, and a stepping motor that rotates at a rotation angle determined for each step is used. Therefore, the lens 3 is moved by a predetermined amount by driving the motor 6 by one step.

The wire 7 is wound around a drive pulley (not shown) fixed to the rotary shaft of the motor 6 and driven pulleys 8 ... Arranged appropriately, and the rotation of the motor 6 is applied to the lens holder 3-1. Then, the lens holder 3-1 is moved.

Further, the mirror 4 is movably provided in order to set the optical path length according to the magnification in response to the movement of the lens 3. That is, the mirror 4 is fixed to the mirror base 4-1 and the mirror base 4-1 is fixed to the guide rail 9
It is provided so as to be movable along. Mirror base 4-
1 has an action portion 4-2 which is brought into pressure contact with the rotary cam 10, and the action portion 4-2 is brought into contact with the cam peripheral surface of the rotary cam 10 by an urging force such as a spring (not shown). It is moved in the left and right directions. The rotation cam 10 transmits the rotation of the motor 6 via a gear or the like, and rotates in a direction corresponding to the rotation direction. Therefore, the mirror 4 is also moved to the position corresponding to the set magnification according to the magnification position of the lens 3.

When the lens 3 has a fixed focus, it is necessary to move the mirror 4 to a predetermined position according to the magnification, but when using a zoom lens that makes the focal length variable according to any magnification. , The mirror 4 is always fixed at a fixed position, and only the lens 3 is moved.

Therefore, the lens 3 is placed at a position corresponding to the magnification.
In order to move the lens, a detection plate 11 for lens positioning is arranged in parallel with the lens guide 5. As shown in FIG. 2, the detection plate 11 has a plurality of (six) fixed magnifications set in advance, for example, 64%, 70%, 75%, 80%, 1
The slits 12 corresponding to the magnification positions of 00% (equal magnification) and 122% are formed. An optical sensor 13 is fixed to the lens holder 3-1 to detect the slit 12. Therefore, the lens 3 is moved by driving the motor 6, and when the magnification of 80% is set, the slit 1 of 80%
When the optical sensor 13 detects the positions 2-3, the lens 3 is positioned at the set magnification. The optical sensor 13 comprises a light emitting and receiving element and a slit 1
When it corresponds to 2, the light is received, or the opposite light at the non-slit position is received. In the following description, it is assumed that the optical sensor 13 turns on when it detects a slit. FIG. 3 is a block diagram relating to movement control of the lens 3 to a position according to the set magnification. In the figure, a control means (CPU) 21 for performing various controls according to a ROM (not shown) in which a program for a copying operation of a copying apparatus is recorded in advance has necessary information, that is, magnification setting information and slit setting information in the present invention. A RAM 21 that stores position information and the like, and an operation unit 22 on an operation panel of the copying apparatus are connected. The motor 6 is driven and controlled according to the control of the CPU 20, for example, when the CPU 20 inputs a slit detection signal from the optical sensor 13. That is, the CPU 20 drives (step-drives) the motor 6 based on the slit detection signal in accordance with the set magnification input via the operation unit 22, and the lens 3
Is positioned at a position corresponding to the input set magnification.

With the above arrangement, the lens position control according to the present invention will be described below with reference to FIGS.

First, the lens position control by the initial setting after the copying machine is powered on will be described with reference to FIGS.

When the power of the copying machine is turned on, the lens 3
Is moved to the slit position 12-5 at the copy magnification of 100% (equal magnification) of the detection plate 11 shown in FIG. That is,
Before turning on the power, the position of the lens 3 could not be specified,
Set 100% position to identify it.

When the initial setting control of the lens is started, C
The PU 20 first sets the lens motor 6 in step n1 of FIG.
Is driven in reverse (rotational drive in the direction in which the lens 3 is moved to the right, that is, in the reduction direction). After the motor 6 is reversely driven to switch the phase of the motor in step n2, whether or not the lens sensor 13 has detected the slit 12 of the detection plate 11 is determined in the next step n3. If the slit 12 is not detected, step n2
Then, the phase of the lens motor 6 is switched again.

The phase switching in step n2 and the like is as described in detail in FIG. 7, which will be described.
When the subroutine of FIG. 7 is called, the CPU 20 first sets the time limit (predetermined time) in the timer T1 in step n101, and when it confirms that the time set in the timer T1 has ended (n102), It is determined whether or not the lens motor 6 is driven in the normal direction (n103), and in this case, it is determined that the lens motor 6 is driven in the reverse direction. Signals LM1, LM2, LM3, LM4
give. As a result, the phase switching for the reverse rotation driving of the lens motor 6 is performed, and the one-step driving is performed.
Then, the process returns to the flow shown in FIG.

By repeating the above control, the sensor 13
When the slit 12 is detected, the process proceeds to step n3 → n4, and the CPU 20 clears the pulse counter (“0”).
To do. The pulse counter acts as a counter that is incremented by +1 each time a predetermined area of the RAM 21 is set and the lens motor 6 is driven one step. That is, the number of phase switching (1 step driving) of the lens motor 6 is counted. Therefore, after clearing the pulse counter, C
The PU 20 again controls the phase switching (n5) of the lens motor 6 according to the subroutine of FIG. 7 to perform one-step driving (reverse rotation). Then, at n6, it is determined whether or not the sensor 13 has detected (ON) the slit 12, and the sensor 13 can detect the slit 1 even after the motor 6 is driven one step.
If 2 is detected, the pulse counter is + in n7.
Count up by 1. After this count-up, it is determined in n8 whether the count number of the pulse counter is "15". This is the slit 12 of the detection plate 11 being detected.
Alternatively, the detection plate 1 further to the right of the slit 12-1 shown in FIG.
This is for distinguishing whether the position deviates from 1.

Therefore, the width of the slit 12 of the detection plate 11 is set so that the lens 3 will pass through the slit when driving 10 steps in this embodiment. Therefore, if the pulse counter counts "10" during the movement of the lens 3 while the sensor 13 is detecting the slit 12, then the sensor 13 is in the non-detection state, that is, the detection plate 1
It becomes OFF at 1. From the above, if it is the slit 12, the pulse counter in step n8 is "15".
While counting the above, in step n6 the sensor 1
3 does not detect the slit 12, and steps n2 and n
The drive of the motor 6 for detecting the slit at 3 continues further.

With the above control, the CPU 20 drives the motor 6 in the reverse direction to move the lens 3 once to the slit 12 of the detection plate 11.
If you move to a position outside the formal area of step n
8 and the motor 6 is stopped at step n9 in FIG. 6 (O
FF) Then, at step n10, 100 mse
The subroutine for performing the interval processing of c is executed, and the process proceeds to step n11 where the lens motor 6 is turned on,
Forward drive is started.

When the normal rotation driving of the motor 6 is started in step n11, the control for detecting the position of the slit 12-5 of the detection plate 11 at the same magnification (100%) is executed.
Therefore, the slit counter M ₀ for indicating the slit position is set in the desired area of the RAN 21, and this state is always stored. That is, in the slit 12-1 which is first detected by the normal rotation driving of the motor 6, the slit counter M ₀ provided separately from the target slit counter M ₀ set above is incremented by +1. And slit 1
Each time 2 is detected, the slit counter M is incremented by +1 and the lens 3 is stopped at the position where the slit counter M counts "5". That is, the count content of the slit counter M matches the slit counter M ₀ that stores the set target value.

To explain the above in more detail, at steps n12 and n13, this is repeated until the sensor 13 detects the detection plate 11 (OFF). Then, when the detection plate 11 is detected, the content of the slit counter M set in a desired area of the RAM 21 is cleared (“0”) (n14), and in steps n15 and n16, the slit of the detection plate 11 is detected by the sensor 13. When the detection state of 12 (12-1) is determined and the slit 12 is detected, the slit counter M is incremented by 1 (n17), and it is determined whether the content of the slit counter M is "5". Now slit 12-
If it is based on the detection of 1, the slit counter M is "1" and the slit 1 is detected in steps n19 and n20.
It is determined whether or not 2-1 has been passed. Slit 12-1
If it passes, the process returns to steps n15 and n16 to execute the control for detecting the next slit 12-2. When the lens 3 is moved to the position of the slit 12-5 by the step driving of the motor 6 by repeating such operations, the slit counter M is incremented by 1, the content becomes "5", and the control routine of n18 is skipped. To execute.

This control routine starts with step n.
At 21, the pulse counter described above is cleared. For subsequent control, the lens 3 is moved to the slit 12 of the detection plate 11.
The motor 6 is driven to position it at the center of (12-5). Therefore, first clear the pulse counter (n2
1) Then, set the content to "0". And step n2
Every time the phase switching for driving the motor 6 by one step is executed at 2, the pulse counter is incremented by +1 (n23). This is repeated until the pulse counter counts "5". Therefore, the slit 12
Is set so as to correspond to the 10-step driving of the motor 6, the lens motor 6 is turned off (n25) after the 5-step driving, that is, when the pulse counter counts "5". Thereby, the slit 12
From the time of detection of −5, the lens 3 is stopped at the center of this slit 12-5. This position is positioned as the initial magnification of 100% (equal magnification), and the initial setting is completed.

By the above procedure, the CPU 20 completes the initial setting to control the movement of the lens 3 to the position corresponding to the magnification input through the magnification setting input section provided in the operation section 22 described above. To do.

Therefore, when the magnification is input by the input means in FIG. 8, if the current magnification and the set magnification are the same, the state is maintained as it is, and if the set magnification is different from the current magnification (changed). If so, the process proceeds from step n201 to n202 assuming that the set magnification has been changed. In the processing of the CPU 20 in step n202, the input set magnification is such that the fixed magnification of the slit detection plate 11 shown in FIG. 2 is, for example, 64%, 70%, 75%, 80%, (10
0%) or 122% is determined. That is, it is determined whether the input magnification matches any of the fixed magnifications corresponding to the slits. Then, the process proceeds to step n203, and if there is the same fixed magnification, the processing of n204 is executed, and if there is no same magnification, the processing of n207 is executed.

In step n203, if the set magnification is the same as the magnification of the slit position of the detection plate 11, the lens 3 is moved to the slit position determined as a fixed magnification that is determined in advance, and the CPU 20 operates according to the input set magnification. , The slit position of the magnification to be moved is calculated. For this calculation, each slit 12 of the detection plate 11 has a number in advance, that is, 64% is "1" (slit 12-1), 70%.
% Is set as “2” (slit 12-2) ..., 122% is set as “6” (slit 12-6), and if 64% of reduction is input, it is set as “1” first. The data is stored in another slit counter M ₀ corresponding to the slit counter M described in 1. The above-mentioned value stored in the slit counter M ₀ , the position where the lens 3 is currently stopped (the value indicating the position stored in the slit counter M, and the step counter corresponding to a predetermined magnification position with respect to the slit position). (The position stored in) is compared (n20
By doing 5), the direction in which the lens 3 is to be moved is determined. That is, at the current position of the lens 3, the content of "5" is stored in the slit counter M at the time of initial setting. If the stop position of the lens 3 is a magnification position other than the slit position, the contents of the slit counter M indicating the slit position closest to the magnification and the magnification position corresponding to a predetermined pulse from that position are stored. The stop position can be specified by the contents stored in the counter.

Therefore, by comparing the current stop position of the lens 3 with the slit position according to the set magnification, when the magnification is smaller (more reduction side), the lens 3 is reduced side (direction in which the motor 6 is reversed). ), Or to the enlargement side when the magnification is large. In this example, if 64% magnification is set after the initial setting, the routine shown in FIG. 10 is executed to move the lens 3 in the reduction direction, assuming that the magnification becomes smaller. Further, if the 122% magnification setting has been made, the routine shown in FIG. 9 is executed so as to move the lens 3 in the enlargement direction.

On the other hand, if the input magnification is not the slit position corresponding to the fixed magnification in step n203, the slit position closest to the magnification input in step n207 is obtained. This is because the magnification of each slit 12 is 64%, 70%, 75%, 80%, 100%, 122
It suffices to find out which of the two is closest to each other. When the lens is located at the center between the fixed magnifications, the slit position that passes first in the lens moving direction is given priority over the current lens position. Good. Alternatively, the smaller or larger magnification may always be selected.

Next, when the closest slit position is obtained, the number of steps by the motor 6 from the slit position to the input magnification position is calculated. That is, the motor 6
If the number of steps in step 1 is proportional to the magnification for each 1%, the remaining magnification value after subtracting the magnification at the slit position and 1
It can be calculated by multiplying the motor step number m corresponding to%. However, if the number of steps by the motor 6 and the change in magnification at every 1% are all different, the number of steps corresponding to each magnification is stored in advance in a memory (ROM or the like), and the number of steps corresponding to the magnification is stored. Should be read. In this case, the number of steps for each magnification may be stored in the memory with reference to each slit position.

Then, in step n209, the reference slit position obtained as described above and the position (magnification) corresponding to the current lens stop position are compared in the same manner as in n205, and the reference slit and the lens stop position are determined. In the case of the same slit position, the moving direction of the lens is determined in n211 and in the case of not the same slit position, the moving direction of the lens is determined in n212. As with n206, the movement direction is determined as to whether the magnification position input with respect to the current lens stop position is large or small. Therefore, CP
U20 executes the routine shown in FIG. 11 when the set and input magnification in n211 is larger than the current stop position, and when the set and input magnification is smaller, it is shown in FIG. To execute the routine. Also, CPU
In n212, 20 executes the routine shown in FIG. 12 when the target slit position closest to the input magnification is larger than the corresponding slit position being stopped, and the set and input magnification is smaller. Sometimes the routine shown in FIG. 13 is executed.

In FIG. 9, the CPU 20 normally rotates the motor 6 to move the lens 3 from the current position to the input magnification position, and moves it in the direction of increasing the magnification. At this time, when the lens 3 is at the position corresponding to the slit (the position corresponding to 100% at the time of initial setting), the motor 6 is normally rotated and moved so as to be out of the slit (n213 to n217). In this case, if the lens 3 is not at the magnification position corresponding to the slit regardless of the initial setting, the motor 6 is driven in the normal rotation direction (n218). It is checked (n220) whether the slit 12 of the detection plate is detected by the sensor by the normal rotation driving of the motor 6. If any slit 12 is detected by this check, the content of the slit counter M is incremented (n221). The slit counter M is a counter that stores the magnification position corresponding to the position where the lens 3 was stopped before moving the lens 3. Therefore, the content of the slit counter M is incremented each time a slit is detected in the moving direction, that is, in the direction in which the magnification is large.

As described above, the slit counter M is counted up each time the slit is detected, and the contents of the slit counter M ₀ stored corresponding to the input set magnification are compared (n222, n223), and If not, make sure that it passes through the slit position (n224, n2
25) After (operation for detecting the next slit 12)
Then, the control for detecting the next slit is executed at n219 and n220.

When the slit counter M matches the slit counter M _{0 of the} target input magnification, the subroutine shown in FIG. 6 for positioning the slit 12 at the center of the slit 12 is executed. That is, n21 to n shown in FIG.
In the processing of n25, movement control for moving the lens 3 to the center of the target slit 12 is performed. If a magnification smaller than the magnification of the current lens stop position is set and input in step n206 of FIG. 8, lens movement control is executed as shown in FIG. This is different only in that the lens motor 6 in FIG.
The other controls are the same. Moreover, when the lens 3 is driven to rotate in the reverse direction by the lens motor 6, the content of the slit counter M is counted down (n239) every time the slit is detected, and the slit position corresponding to the target magnification is stored in the slit. A comparison with the counter M ₀ is performed and the slit is positioned at the input target magnification position.

The above is the movement control for positioning the lens 3 at the slit position where the input set magnification corresponds to a plurality of fixed magnifications.

Position control for moving the lens 3 to a position having a magnification different from the fixed magnification corresponding to each slit will be described with reference to FIGS.

When it is determined at n211 in FIG. 8 whether the moving direction of the lens 3 is the expansion or contraction direction, the routine of or of FIG. 11 is executed. When the routine is executed, the motor 6 is driven in the normal direction until the motor 6 is detected whether it is out of the slit indicating the lens position (n252).
Is driven one step. The number of pulse steps corresponding to the input magnification calculated in step n208 of FIG. 8 by being out of the slit is set in the pulse counter (n2
53) is performed. Then, the motor 6 is driven by one step (n
Every time 254), the contents of the pulse counter are counted down. In this case, apart from the pulse counter,
A step counter for storing the number of steps corresponding to the input magnification calculated in n208 is provided, and the lens 3 is determined by the contents of the step counter and the slit counter M.
The magnification position of can be specified. Therefore, the contents of the step counter are set in the pulse counter, and the contents of the step counter are held as they are until the number of steps corresponding to the next input magnification is newly stored.

By performing the one-step driving of the motor 6 as described above, the content of the pulse counter is counted down, and when the counted content becomes "0", the driving of the motor 6 is stopped.

On the other hand, when the routine of (1) is executed, the motor 6 is driven in reverse, and the same position control as in the case described above is executed. Here, the number of steps for driving the motor 6 is different from the position of the reference slit 12 in the moving direction of the lens 3 even at the same magnification. For example, when the input setting magnification is 85%, the reference slit is 12-5.
The number of steps from 100% (equal size) and slit 12
-4 is different from the number of steps from the 80% position. Therefore, as for the number of steps corresponding to the corresponding 1% magnification from each slit position, the number of steps corresponding to the target magnification is determined depending on whether the movement is in the enlargement direction or the reduction direction with reference to the slit. It is good to remember each one.
Alternatively, when only the number of steps when moving from the respective slits to be the reference in the enlargement direction is stored, the number of steps when moving from each slit to the reducing direction is the total number of steps between each slit ( It may be obtained by subtracting the number of steps of the corresponding magnification from (the total number of steps of driving the motor 6 when moving the slits from the adjacent slits).

Next, in order to position the lens 3 at a slit position where the input magnification is different from the slit position corresponding to the current stop position and at a magnification corresponding to a predetermined slip number from the reference slit position, FIG. The routine for determining n212 in step S21 will be described with reference to FIGS.

First, in n258, the content (numerical value) corresponding to the slit position obtained in n207 of FIG. 8 is set in the slit counter M ₀ , and the motor 6 is driven in the normal direction (n25).
9, n260), and it is checked whether the sensor detects the slit 12 of the detection plate (n261).

When the slit is detected, the slit counter M
Is counted up (n262), and the slit counter M storing the contents before driving the motor 6 (the slit position corresponding to the stop) is compared with the contents of the slit counter M ₀ set by the input (n263, n263). n26
4) Do. When it becomes the same as the target slit position input by the step driving of the motor 6, the moving direction from the reference slit position to the desired input magnification position is determined (n265, n266). At this time, if the moving directions are the same, the routine shown in FIG. 14 is executed, and if the moving directions are opposite, the routine after executing the routine shown in FIG. 14 is executed.

The routine of FIG. 14 is as shown in FIG. 14, and the same control as steps n253 to n257 of FIG. 11 is executed. That is, the number of steps corresponding to the input magnification calculated in n208 of FIG. 8 is set in the pulse counter (n280), the motor 6 is continuously step-driven (n281), and the content of the pulse counter is incremented for each step driving. Is counted down, and when the content of this pulse counter becomes "0", the lens motor 6 is stopped.

This routine is another control, that is, the control in the case of driving the motor 6 in the reverse direction after the detection of the reference slit. First, the motor 6 is once stopped (n285) and then 100
After the interval (n286) of msec, the motor 6 is reversely driven (n287, n288), the slit position is confirmed (n289), the step drive of the motor 6 is continued, and the lens 3 is moved to the end (edge) of the slit 12. Move (n2
90, n291). After that, the processing from n280 onward is performed in order to execute the routine described above.

At the final stage, in n212 of FIG. 8, when the movement of the lens 3 in the reduction direction is judged, that is, when the target input set magnification from the reference slit is on the reduction side, the routine shown in FIG. To execute. In this case, contrary to the control routine of FIG. 12, the motor 6 is driven in the reverse direction to move the lens 3 to the target reference slit position. Before the lens 3 is moved, the contents of the slit position obtained in n207 of FIG. 8 are set (n269) in the slit counter M ₀ and stored. The motor 6 is step-driven (reverse rotation driven), and a slit different from the slit at the present stop is detected (n272) to count down the content of the slit counter M (n273). After this countdown, the slit counter M ₀ that stores the target slit position and the slit counter M are compared (n274, n275), and if they match, the target slit is set as the reference slit position and the motor 6 is driven in the current driving direction. And whether it is in the same direction as (n276, n277)
Then, in the case of the same direction, the motor 6 is continued and driven, and the control routine of is executed. If the motor 6 is in the opposite drive direction, the control routine for temporarily stopping the motor 6 is executed.

As described above, the lens 3 has slits 12-1 to 12-6 in which the input magnification shows a plurality of fixed magnifications.
If any of the above conditions is met, the movement is controlled to the position of the input magnification by detecting the slit. When the input magnification is other than the fixed magnification corresponding to the slit, the target slit is obtained, and the motor 6 is driven from the target slit position by the number of steps corresponding to the magnification so that the lens 3 receives the input magnification. The position is controlled to.

The number of slits is not limited to this embodiment and may be set to any number. Further, the present invention is not limited to the copying machine of the present embodiment, but can be used for projection on a subject at various magnifications using a lens.

[0057]

As described above, according to the present invention, when the input magnification is a fixed magnification, it can be positioned at the slit position corresponding to the fixed magnification, and when it is not fixed, it is close to the input magnification. Positioning is performed by obtaining a target slit and step-driving from the target slit. Therefore, the amount of step driving from the reference slit position is small, and since the movement is controlled from the reference slit position each time the magnification is changed, the lens position can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is a plan view showing an optical system of a copying machine of the present invention.

FIG. 2 is a perspective view showing details of a detection plate with a slit.

FIG. 3 is a block diagram showing a lens control system of the copying machine of the present invention.

FIG. 4 is a CPU when the lens motor is step-driven.
6 is a timing chart showing a drive signal given to the lens motor from the.

FIG. 5 is a CP in the lens initial operation of the embodiment.
The flowchart which shows a part of U control procedure.

FIG. 6 is a CP in the lens initial operation of the embodiment.
The flowchart which shows the continuation of the control procedure of U.

FIG. 7 is a flowchart showing the control procedure of the CPU for step driving in the phase switching processing of the lens motor.

FIG. 8 is a flowchart showing a control procedure for determining the moving direction of the lens motor of the CPU in the setting magnification changing process of the embodiment.

9 is a flowchart showing a control procedure continued from FIG. 8 of the CPU in the position control of the lens motor to the slit position according to the set magnification.

10 is a flowchart showing a control procedure continued from FIG. 8 by the CPU in the position control of the slit position of the lens motor according to the set magnification.

FIG. 11 is a flowchart showing a control procedure subsequent to FIG. 8 of the CPU for stepwise driving the lens motor from the slit position corresponding to the set magnification.

FIG. 12 is a flowchart showing a control procedure continued from FIG. 8 of the CPU for controlling the position of the lens motor up to the slit position corresponding to the set magnification.

FIG. 13 is a flowchart showing a control procedure continued from FIG. 8 of the CPU for controlling the position of the lens motor up to the slit position corresponding to the set magnification.

FIG. 14 is a flowchart showing a control procedure of the CPU for step driving the lens motor from the slit position corresponding to the set magnification, which is subsequent to FIGS. 12 and 13;

[Explanation of symbols]

3 lens 3-1 lens holder 5 lens guide 6 step drive lens motor 7 wire 11 detection plate 12 (12-1, 12-2, 12-3, 12-4, 12
-5, 12-6) Slit (for fixed magnification) 13 Slit detection sensor 20 CPU 21 RAM 22 Operation part

Claims (1)

[Claims] 1. A lens provided so as to be movable along a moving path in accordance with a magnification, a motor driven stepwise to move the lens to a predetermined magnification position, and arranged along the moving path of the lens. A detection plate having slits formed in accordance with a plurality of fixed magnifications, a detection means for detecting the slits of the detection plate, an input means for setting an arbitrary magnification, and the input means. And a means for deciding whether or not the set magnification is a fixed magnification and recognizing that the discrimination means is a fixed magnification. In response to slit detection according to the predetermined magnification of the detection plate, the drive of the motor is stopped, and the set magnification is set after driving to the slit position corresponding to the fixed magnification that is close to the set magnification input when the magnification is other than the fixed magnification. Corresponding number of steps: A lens position control device comprising: motor drive control means for driving and stopping the motor.