JPH034219A - Method for controlling stop position of optical system - Google Patents

Abstract

PURPOSE:To stabilize a copy image by setting an initial stop position directly before an image to be obtained is copied. CONSTITUTION:When a copy button 51 is turned on, it is confirmed that a home position sensor HPS is on and then it is confirmed that a mirror base MB1 is in the range of a determined home position. Then a CPU 52 rotates a DC motor 54 clockwise through a motor driver 53 until the direction A where a base MB1 is fed and the motor 54 is rotated at a low speed to continue feeding operation. The base MB1 is set to a speed of 50 mm/sec, almost stop ping speed, and when the MB1 moves forth until the rear end of a detection piece 34a leaves the detection part of the home position sensor HPS, the rotation of the motor 54 is stopped. Consequently, the stop position of the optical system can be determined with extreme accuracy, so the time of movement from the stop position of the optical system to the front end of an image has no devia tion, synchronism with other sequence timing is accurately acquired, thus the copy image is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the stop position of an optical system used in an image forming apparatus, an image reading apparatus, or the like.

(Prior Art and Problems with the Prior Art) In general, in an optical system movable copying machine, a document is scanned at a constant speed when the optical system is fed, and the original is returned to the home position at high speed when returning. A home position sensor is placed at the home position,
Also, the optical system usually has 201. ~309. A detection piece having a certain length is provided, and the sensor and the detection piece detect that the optical system has returned to the home position and stop the optical system at a predetermined position. The method for stopping this optical system is to brake the optical system to a stop at the moment the optical system returns to its home position and the detection piece provided in the optical system reaches the detection part of the sensor, and the detection piece then stops at the detection part of the sensor. The system was configured to stop in a state corresponding to the following.

That is, as shown in FIG. 7(a), at the moment when the tip of the detection piece of the optical system in the direction of arrow R reaches the detection part S of the home position sensor HPS, the detection piece of the optical system returns in the direction of arrow R. Performs stop braking of the optical system. Then, the optical system moves in the direction of arrow R due to some inertia and stops. As shown in FIG. 7(b) to FIG. 7(C), this stopping position is somewhat affected by the braking condition, inertia force, etc. at that time, but the detection part S of the sensor HPS The detection piece K stops in the corresponding state. At this time, the braking state and the change in the stopping position due to inertia force can be determined by assuming that the detection piece is 20-
If it has a length of , the stopping position of the optical system will change with a width of at most 20.

Incidentally, in addition to the home position sensor described above for detecting and determining the initial position of the optical system, a typical copying machine is provided with a timing switch at a position corresponding to the leading edge of the image of the original. This timing switch starts timing from the moment the detection piece reaches the timing switch during feeding of the optical system, and measures sequence timing such as turning on the registration roller provided for conveying the transfer paper after a predetermined time. used for. When making a normal copy, the time required for an exposed area on the photoreceptor to reach the transfer position at the exposure position where a latent image is written on the photoreceptor is the time when the transfer paper starts the registration rollers and reaches the transfer position. It is set longer than the time. In other words, the optical system is positioned at the leading edge of the original image (timing switch position).
(the optical system is at a stable speed), and after a certain period of time, the registration roller is turned ON and the transfer paper is started. In other words, since the sequence timing is activated based on the timing switch, the optical system is at the stop position of 207. Even if there was some degree of deviation, the image did not shift forward or backward.

When making a normal copy using a copying machine as described above, it is possible to set the sequence timing of the registration rollers and the like according to the movement of the optical system using a timing switch provided at the leading edge position of the image of the original. however,
As described above, it is not always possible to measure the sequence timing by detecting that the optical system has reached the leading edge of the image. To give an example of this, an image at a predetermined position on a document as shown in FIG. 8(a) is moved downstream in the direction of movement of the optical system in the copy, as shown in FIG. 8(b). There are cases where this is desired. In such a case, the transfer paper is normally transferred from the timing when it starts from the registration roller (a predetermined time after the optical system reaches the leading edge of the image) for the time corresponding to the image movement distance, as shown in Figure 8. The paper must start early from the registration rollers.

In this way, when the transfer paper is started at an earlier timing than usual, if the start timing is before the optical system reaches the leading edge of the original image, the sequence timing is measured using the timing switch at the leading edge of the original image as described above. Instead, the start timing of the registration rollers must be determined based on the home position sensor. Furthermore, if the timing of the registration roller is further advanced, the optical system may be started from the home position after a predetermined time after the registration roller is turned on. In all of these cases, it is assumed that the time it takes for the optical system located at the home position to reach the leading edge of the image of the document is constant. However, in reality, as mentioned above, the stop position of the optical system has an error equal to the length of the detection piece installed in the optical system at the home position sensor position, so the stop position of the optical system is longer than the set time by the amount corresponding to that error. It may arrive at the leading edge of the document early or late. As a result, the image is moved to a position that is considerably different from the originally required image movement distance.

To solve this problem, in order to stop the optical system at a precise position when returning, the optical system is braked in several stages as it returns at high speed, and in the final stage it is braked in several stages. It is conceivable to return the optical system at high speed and stop it at a predetermined timing.

In this way, in the final stage, the optical system is moving at a speed just before stopping, so if the stop braking is performed at a predetermined timing, it is possible to stop the optical system at a fixed position without error. However, the speed at the final stage or the stop braking start position may vary depending on various factors, such as repeating deceleration braking several times before reaching the low speed at the final stage, and the speed at the next stage being affected by the speed inertia of the previous stage. This has the disadvantage that the position of the optical system is unstable due to fluctuations.

(Objective) The object of the present invention is to solve the above-mentioned conventional drawbacks, and to solve the above-mentioned drawbacks of the conventional optical system. The purpose of this is to stabilize the stopping position of the vehicle.

(Means for Solving the Problems) A method for controlling the stop position of an optical system according to the present invention scans a document by driving the optical system in the scanning direction, returns the optical system to the home position after scanning the document, and returns the optical system to the home position. The optical system is stopped at a position corresponding to a stop position detection sensor installed at the position, the optical system in this stopped state is driven at a low speed, and the drive of the optical system is stopped according to the output of the stop position detection sensor. This is a characteristic feature.

Further, in the method for controlling the stop position of an optical system according to the present invention, an original is scanned by driving the optical system in the scanning direction, and after scanning the original, the optical system is returned to the home position, and a stop position of the optical system is set at the home position. The optical system is stopped at a position corresponding to the first sensor, and the optical system in this stopped state is driven at an extremely low speed to correspond to the distance between the first sensor and a second sensor installed adjacent to the first sensor. The present invention is characterized in that the drive of the optical system is stopped when both of the above sensors detect a position detection piece having a length of

(Embodiment) FIG. 2 is a schematic structural diagram of a copying machine in which the method for controlling the stop position of an optical system according to the present invention is implemented.

A photosensitive drum 2 is arranged approximately in the center of the copying machine body 1, and around it are a charging device, a developing section, and a transfer device.

An optical system 3 including a zoom lens 30 that moves horizontally according to the set magnification is arranged above the photoreceptor drum 2, and a paper feed tray is arranged on the right side of the photoreceptor drum 2. A paper feeding section 4 including a cassette loading section and a cassette mounting section, a conveyance section 5 for conveying the paper after transfer, and a fixing section 6 consisting of two rollers are arranged on the left side. A document cover 7 is rotatably attached to the top of the copying machine body 1, and by setting a document under this cover, an image corresponding to the document is formed on the photoreceptor drum 2 by the feed scanning of the optical system 3. . A paper feed roller 40 that conveys paper from the paper feed unit 4 toward the photosensitive drum 2 is connected to a paper start clutch P to align the leading edge of the paper with the leading edge of the image on the drum.
Drive timing is controlled by SC. The ON/OFF timing of the paper start clutch PSC is controlled by a CPU for optical system movement control, which will be described later.

FIG. 3 is a perspective view of essential parts of the optical system 3 of the copying machine. The optical system scanning section 31 of the optical system 3 that scans the original includes a light source 31a and two mirrors 3lb.

31c, and a mirror base MB2 that supports a mirror 31d that reflects light from an original onto a mirror 31b. These mirror bases MBI and MB2 are supported by two rails 32 and 33 so as to be slidable in the horizontal direction. Mirror base M
One side 34 of the BI is fixed to a wire 35, and as the wire 35 moves in the A or B direction, the mirror base MB
Both IMB2 move in the A direction (feed direction) and the B direction (return direction). The wire 35 is wound around a pulley 36 and the rotating shaft of a DC motor (not shown), so that the mirror bases MBI and MB2 reciprocate as the motor rotates forward and backward.

The wire fixing side portion 34 of the mirror base MBI has a detection piece 34a, and a home position sensor HPS that detects the detection piece 34a is provided in the stop area of the mirror base MBI.
However, a start position sensor SPS is also arranged adjacent to the home position sensor HPS and on the downstream side of the mirror base MBI in the scanning direction. As this sensor, a photo ink converter, a micro switch, etc. can be used. When the mirror base MBI returns, deceleration braking and stop braking are applied from when the start position sensor SPS is turned off, and the mirror base MBI is stopped at a position corresponding to the home position sensor HPS. That is, in the case of this embodiment, the home position sensor HPS constitutes the stop position detection sensor.

Next, the control section of the copying machine in this embodiment will be explained with reference to FIG.

When the copy button 51 is turned on, the CPU 52 drives the DC motor 54 for driving the optical system via the motor driver 53. Then, when the detection piece 34a provided on the mirror base MBI of the optical system passes the position corresponding to the home position sensor HPS and start position sensor SPS, the CPU 52 detects the ROM 5 based on the output of each sensor.
The DC motor 54 is driven via the motor driver 53 according to a sequence program written in advance in the DC motor 54.

Next, a method for controlling the stop position of the optical system in this embodiment will be explained with reference to FIGS. 1 and 5.

Before the copy button 51 is turned on, the mirror base MBI of the optical system is located at the home position. To explain in more detail, as shown in FIG. 5(a), the detection piece 34a of the mirror base MBI is connected to the home position sensor H.
It blocks the detection part S of the PS and stops (HPS is turned ON in this state). As shown in Figure 1, when the copy button is turned on, the home position sensor HPS is turned on.
It is confirmed that the mirror base MBI is within the predetermined home position range. Then, the CPU 52 uses the DC power via the motor driver 53.
Rotate the motor 54 clockwise (C, W).

). In this example, this clockwise rotation is
This corresponds to the direction A in which the mirror base MBI is fed. The DC motor 54 rotates at an extremely low speed, and when the speed of the mirror base MBI reaches 2, it continues feeding while maintaining that speed. The rotation of the DC motor 54 is controlled so that the speed V2 of the mirror base MBI is extremely low, that is, the speed is close to stopping. More specifically, if the speed ■2 setting is 50″′″′/□ゎ or less,
It has been confirmed that the object of the present invention can be fully achieved.

The mirror base MBI moves forward, and as shown in FIG. 5(b), the rear end of the detection piece 34a is connected to the home position sensor HP.
The rotation of the DC motor 54 is stopped at the moment when it passes through the detection part S of S (HPS=OFF). In this way, since the mirror base MBI is originally moving at an extremely low speed on the verge of stopping, it will be in the state shown in FIG. 5(b), or will move somewhat in the feed direction A and then stop. Even if it moves a little in the feed direction A and stops, the distance is extremely small, and if the detection piece turned on the home position sensor as in the past, it was considered to be the normal stopping position. Compared to similar devices, the home position and stop position of the mirror base MBI can be determined with much greater precision. Therefore, the home position sensor HPS is OFF.
Even if you set the timing for turning on the registration roller from the timing of , or feed the optical system after turning on the registration roller, it is possible to accurately obtain the desired image without affecting the image position. can.

In addition, in any of the above cases, the mirror base MBI
The time from the home position stop position to the start position can be kept constant with almost no error.

Then, from the timing when the copy button is turned on (actually, the mirror base MBI moves to the initial stop position when the copy button is turned on, so the home position sensor HPS is turned off.
), the time (t++tz) for the mirror base MBI to reach the start position is set in advance according to the copy mode, and the time L2 for the mirror base MBI to start feeding is adjusted to correspond to various modes. I try to do that.

Mirror-based MBI has a stable feed speed at the starting position ■. This speed has reached ■. to scan the image area and reach the return position preset according to the document size. This return position is the speed of the mirror base MBI ■.

Then, the return position can be determined by calculating the scanning time from the document length and starting time measurement from the ON timing of the start position sensor.

When the mirror base MBI reaches the return position, the motor, which had been rotating in the clockwise direction (C1W,), switches its rotation to the opposite direction (C, C1W,). In response to this, the mirror base MBI is decelerated and braked, and after stopping, starts moving in the return direction. The return speed ■ is driven at a relatively high speed, and when the start position is reached, that is, when the detection piece 34a turns on the start position sensor SPS as shown in FIG. 5(C), the mirror base MB
I starts deceleration braking and the home position sensor HP
Before reaching S, it is decelerated to speed ■. This speed■
, has some inertia when the motor stops rotating,
The speed is such that the mirror-based MBI advances only a small distance.

When the mirror base MBI reaches the home position sensor HPS (HPS=ON), the motor stops rotating. As mentioned above, the speed ■ is relatively low, so the mirror-based MBI moves by an amount corresponding to some inertial force, but the amount is minute, and specifically, the detection piece 34a is the home position sensor. This prevents the HPS from overrunning. This state is shown in Figure 5(a).
It corresponds to the state shown in .

According to this control method, the braking when the optical system returns can be set without considering various factors, and the initial stopping position of the optical system can be set independently of the speed and braking during the return, and it can be set accurately. You can set the stopping position. Furthermore, since the initial stopping position of the optical system is accurate, the distance from this position to the leading edge of the document, in other words, the movement time is stabilized, so that errors in sequence timing are extremely reduced.

Furthermore, according to the above embodiment, the initial stop position is set after turning on the copy button, that is, before directly copying the desired image, so the reliability is lower than that in which the stop position is determined at the time of return. Very expensive.

Next, another embodiment of the method for controlling the stop position of the optical system will be described.

The difference from the previous embodiment is that the length of the detection piece 34a is different from that of the home position sensor HPS, as shown in FIG. 6(b).
The distance between the detection section S of the start position sensor SPS and the detection section S of the start position sensor SPS is made to correspond approximately to the distance between the detection section S of the start position sensor SPS and the detection section S of the start position sensor SPS. In order to determine the stop position of the optical system by this, first, the detection piece 34a of the optical system is stopped with either the home position sensor HPS or the start position sensor SPS turned ON, and then the optical system is turned OFF. Drive at extremely low speed toward the sensor on the side that is set to .

That is, in the embodiment, the detection piece 34a (optical system) stopped at the position shown in FIG. When this is reached (HPS=ON), the drive is stopped. If the start position sensor SPS, which was originally in the ON state, turns OFF when low-speed driving and stopping is performed in this way, in other words, if the detection piece 34a passes through the start position sensor SPS, the arrow Since it has gone too far in that direction, it should be driven again in the direction of arrow C. The stop position of the mirror base MBI is determined when both sensors are turned on (SPS=ON, HPS=ON) as shown in FIG. 6(b). As is clear from the above embodiments, in this embodiment, the home position sensor HPS and the start position sensor SPS constitute a stop position detection sensor.

Incidentally, when it is driven again in the direction of arrow C and this time it passes the home position sensor (HPS=OFF), it is driven in the direction of arrow C so that it approaches the state shown in FIG. 6(b). At this time, positioning can be further facilitated by reducing the speed each time the drive is repeated in the directions of arrows C and D.

In addition, in the above embodiment, a so-called analog optical system was described in which the image of the original is exposed and the image is guided directly to the photoreceptor, but instead of this, an image sensor such as a CCD may be used to read the original. Alternatively, a latent image may be formed on the photoreceptor by modulating a semiconductor laser or the like with this signal after the electric signal is changed into an electric signal corresponding to the image of the original document.

Furthermore, the present invention can also be applied to an image reading device that uses the image sensor as described above to read an image of a document, converts it into an electrical signal, and stores the electrical signal in a storage device.

(Effects) As explained above, according to the present invention, the stopping position of the optical system can be determined extremely accurately, so there is no deviation in the travel time from the stopping position of the optical system to the leading edge of the image, and there is no difference in timing from other sequence timings. Synchronization is accurate and the image on the copy is stable.

[Brief explanation of the drawing]

FIG. 1 is a timing chart for explaining the stop position control method of an optical system according to the present invention, FIG. 2 is a sectional view of a copying machine in which the present invention is implemented, and FIG. 3 is an optical system in the copying machine shown in FIG. FIG. 4 is a block diagram illustrating a control unit for carrying out the present invention, FIG. 5 is an enlarged view of a main part of the present invention, and FIG. 6 is a main part showing another embodiment of the present invention. FIG. 7 is an enlarged view of a main part for explaining the prior art, and FIG. 8 is a diagram showing an example of image movement. 3... 34a... 54... HPS... MBI... S... SPS... -Optical system, detection piece, DC motor, home position sensor, mirror base, detection unit, start position sensor

Claims (2)

[Claims] (1) Scan the original by driving the optical system in the scanning direction, return the optical system to the home position after scanning the original, and place the optical system at the position corresponding to the stop position detection sensor provided at the home position. 1. A method for controlling the stop position of an optical system, comprising: bringing the optical system into a stopped state, driving the optical system in this stopped state at an extremely low speed, and stopping the drive of the optical system in accordance with the output of a stop position detection sensor. (2) The original is scanned by driving the optical system in the scanning direction, and after scanning the original, the optical system is returned to the home position, and the optical system is moved at a position corresponding to the first sensor provided at the home position. The optical system in the stopped state is driven at an extremely low speed, and the position detection piece having a length corresponding to the distance between the first sensor and the second sensor provided adjacent to the first sensor is set as described above. A method for controlling the stop position of an optical system, characterized in that driving of the optical system is stopped when both sensors detect it.