JPH0453640Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to drive control of an original exposure unit used in a recording device such as a copying machine, and particularly relates to an original exposure unit in which an illumination system and an imaging system are scanned independently. The present invention relates to a drive control device.

[Conventional technology]

Conventionally, in such a drive control device, the illumination system and the imaging optical system that constitute the document exposure section are driven by the same drive system, the image of the document, etc. is exposed, and the exposed image of the document is transferred onto the photoreceptor. was being formed. However, with this control, the illumination system and the imaging optical system are driven by the same drive system, which increases the load on the drive system, making variable speed scanning difficult and causing vibrations in the imaging system. Ta. In order to improve this drawback, recently, a drive control device for a document exposure section has been proposed in which the illumination system and the imaging optical system are separated and each is driven independently.

[Problem that the invention attempts to solve]

However, with the drive control device described above, if the optical axis of the illumination system and the optical axis of the imaging optical system do not match during scanning, the exposure amount of the exposed image formed on the photoreceptor decreases, and the recording paper after transfer There was a problem in that the copy quality of the image recorded on the camera deteriorated.

The present invention was devised in view of the above-mentioned problems, and provides a drive control device for a document exposure section that can synchronize the illumination system and the imaging optical system to align their optical axes when scanning the document exposure section. The purpose is to

[Means and actions for solving problems]

The present invention detects a positional error based on the positions of the illumination system and the imaging system, and controls the driving means of the illumination system and the imaging system so as to be phase synchronized according to the positional error. The axes can be aligned.

〔Example〕

Embodiments of the present invention will be described in detail based on the drawings of FIGS. 1 to 3.

FIG. 1 is a system configuration diagram according to an embodiment of the present invention. In the figure, an illumination system 11 and an imaging system 12 that constitute a document exposure section are driven by separate DC servo motors (hereinafter referred to as DC motors) 13 and 14. Encoders 15 and 16 are attached to the rotation shafts of the DC motors 13 and 14, respectively, and the encoders 15 and 16 output pulses corresponding to the rotation angles of the DC motors 13 and 14. A registration sensor 17 is disposed at a document scanning start (registration) position of the illumination system 11 to detect the registration position of the illumination system 11 and output a detection signal. Further, a position detection sensor 18 is disposed at a predetermined position between the stop position of the imaging system 12 and the registration position in the conveyance path of the imaging system 12.
detects the position of and outputs a detection signal. The detection signals output from the registration sensor 17 and the position detection sensor 18 are both input to a control circuit 19, and position error control of the illumination system 11 and the imaging system 12 is performed. Note that the distance d between the registration sensor 17 and the position detection sensor 18 is constant.

Further, the amount of movement of each illumination system 11 and imaging system 12 and the number of pulses of each encoder 15 and 16 per rotation of DC motors 13 and 14 are set to be equal. Note that the imaging system 12 includes a first mirror 12a,
a second mirror 12b;
moves at 1/2 the speed of the first mirror 12a,
The optical path length is kept constant.

A pulse indicating the movement state of the illumination system 11 outputted from the encoder 15 is sent to an up-down counter 2.
0, 21 and the down counter 22. The up-down counter 20 includes a control circuit 1
A reference pulse from a crystal oscillator 23 whose frequency is controlled by 9 is input, and an up-down counter 20 adds and subtracts the pulse indicating the moving state of the illumination system 11 and the reference pulse, and converts this value into a digital signal.
It is output to an analog (D/A) converter 24.
The D/A converter 24 outputs an analog value corresponding to the input value, the phase compensation circuit 25 compensates the phase of the output of the D/A converter 24, and the amplifier 26 performs pulse width control to drive the servo motor 13. is driven at a constant speed. That is, the up-down counter 20,
The crystal oscillator 23, D/A converter 24, phase compensation circuit 25, amplifier 26, DC motor 13, and encoder 15 collectively constitute a servo control loop for the lighting system, and this control is performed using a PLL (Phase
Locked Loop).

A pulse indicating the moving state of the illumination system 11 is supplied to an input terminal for counting up the up-down counter 21 under the control of the control circuit 19, and a pulse indicating the movement state of the illumination system 11 is supplied to an input terminal for counting down under the control of the control circuit 19. A pulse indicating the movement state of the imaging system 12 is outputted from the encoder 16. The up-down counter 21 is
The pulses input to both terminals are added and subtracted, and this value is sent to the digital-to-analog (D/A) converter 2.
It is output to 7. The D/A converter 27 outputs an analog value corresponding to the input value, the phase compensation circuit 28 compensates the phase of the output of the D/A converter 27, and the amplifier 29 controls the pulse width to drive the servo motor 14. is synchronized in phase with the DC motor 13 of the illumination system 11. That is, up-down counter 2
1, D/A converter 27, phase compensation circuit 28, amplifier 29, DC motor 13 and encoder 15,
The entire system constitutes a servo control loop for the imaging system, and like the illumination system, this control is performed using a PLL (Phase Control Loop).
Locked Loop). Therefore,
The DC motor 14 is driven using a pulse indicating the movement state of the illumination system 11 outputted from the encoder 15 as a reference pulse, so that the position of the imaging system 12 is moved in synchronization with the position of the illumination system 11, and The optical axes can be aligned, and an exposed image of the original can be formed on the photoreceptor 30. Moreover, the amplifiers 26 and 29 are
It is connected to the control circuit 19 and controls the power supply voltage supplied to the DC motors 13 and 14 during start/stop and scan/return.

The down counter 22 is a position error detection counter loaded with a value corresponding to the distance from the stop position of the illumination system 11 to the position detection sensor 18. The down counter 22 counts down the pulses from the encoder 15 when the illumination system 11 starts moving, and outputs the count value when the position detection sensor 18 detects the imaging system 12 to the control circuit 19.

Next, the control operation of the drive control device shown in FIG. 1 will be explained based on the flowchart shown in FIG.

First, when the power is turned on, in step 101, both the illumination system 11 and the imaging system 12 are scanned at the same speed for initialization, and in step 102, the output data of the imaging system up/down counter 21 during synchronization is _nNPD. is read and stored in the memory within the control circuit 19. This output data _nNPD is the output data of the lighting system.
This is a data signal necessary to drive the DC motor 14 of the imaging system in synchronization with the drive of the DC motor 13, and differs for each device depending on the load conditions at the time of setting. Next, in step 103, the lighting system 11,
The return of the imaging system 12 is started, and the number of encoder clocks n _H from the registration sensor 17 to the predetermined stop position of the illumination system 11 is measured and stored in the memory of the control circuit 19 (step 104). The control circuit 19 then controls the illumination system 1 before starting the scan.
The number of clocks _n
5). This lock number _nX is expressed by the following equation.

n _X = n _H − n _dHere , n _H is the resist sensor 1
7 to the stop position of the illumination system 11, and _nd is the number of clocks from the registration sensor 17 to the position sensor 18.
This is the number of encoder clocks corresponding to the distance d between.

Next, in step 106, the illumination system 11 and the imaging system 12 are
drive at the same time to start scanning.
Further, the clock number _nX loaded into the down counter 22 is counted down by the encoder clock of the illumination system DC motor 13 after the scan is started. Thereafter, when the imaging system 12 reaches the position of the position detection sensor 18, the position detection sensor 18 detects the imaging system 12 in step 107, which causes an interrupt to the control circuit 19, and the counter at that point is Read the count value n _e .
This count value _ne becomes a value representing the positional error between the illumination system 11 and the imaging system 12 at the time when the position detection sensor 18 detects the imaging system 12. In other words, if this count value n _e =0, the positions of the illumination system ₁₁ and the imaging system 12 match, and if n _e <0, the imaging system 12 is behind the position of the illumination system 11. , n _e
>0 indicates that the imaging system 12 is ahead of the position of the illumination system 11.

The control circuit 19 subtracts this count value n _e from the output data n _NPD and loads it into the up-down counter 21 (step 108). By performing position error control using the PLL of the imaging system, the imaging system 12 will match the movement position of the illumination system 11 by the time it reaches the position where the registration sensor 17 is placed.

Figure 3 shows how position error control is performed when the imaging system lags behind the position of the illumination system, with Figure 3a showing the position profile and Figure 3b showing the velocity profile. It is a diagram. In Fig. 3a, when the imaging system reaches the position of the position detection sensor t ₂ hours after the start, the illumination system has already reached the position t ₁
It passes the position of the position detection sensor 18 at the same time, and the count value n _e of the counter is n _e <0. Therefore, the control circuit 19 instantly subtracts this count value n _e from the output data n _NPD , and the resulting value (n _NPD −
n _e ) is loaded into the up-down counter 21.
Therefore, the up-down counter 21 is at time t ₂
Thereafter, as shown in FIG. 3b, PLL control is performed in which the speed of the imaging system is inclined to the higher speed side by the loaded value than the speed of the illumination system 11. As a result, the speed of the imaging system 12 temporarily becomes faster than the speed of the illumination system 11, but then convergence to a value corresponding to the speed of the illumination system 11 is performed. Therefore, lighting system 1
By the time t ₃ when 1 is detected by the registration sensor 17, the illumination system 11 and the imaging system 12 can be synchronized.

In addition, if the imaging system is ahead of the illumination system, PLL control is performed so that the speed of the imaging system 11 is tilted to a lower speed side by the loaded value than the speed of the illumination system 12. Synchronization can be achieved by temporarily making the speed of the system 12 slower than that of the illumination system 11, and then counting up to reach the speed of the illumination system 11. Therefore, the illumination system 11 and the imaging system 12 are synchronized from the start of the scan until time _t3 , that is, until they reach the position of the registration sensor 17, so that their optical axes can be aligned, and the registration position can be adjusted. When the illumination system 11 starts exposure from , an exposed image of the original is formed on the photoreceptor 30 with a good exposure amount via the optical device of the imaging system 12 . When the exposure is completed, the illumination system 11 and the imaging system 12 return (step 103) to prepare for the next scan.

[Effect of idea]

As explained above, according to the present invention, the positional error between the illumination system and the imaging system is detected, and the drive means for the illumination system and the imaging system are adjusted in phase until the illumination system reaches the exposure position. Since the optical axes are made to coincide with each other through synchronization control, there is no decrease in exposure amount, and deterioration in copy image quality can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a drive control device for a document exposure section according to the present invention, FIG. 2 is a flowchart showing the control operation of the device in FIG. 1, and FIGS. 3a and 3b are lighting FIG. 4 is a diagram showing the position profile and velocity profile of the system and the imaging system. 11...Illumination system, 12...Imaging system, 13, 14
...DC servo motor (DC motor), 15, 16
... Encoder, 17 ... Registration sensor, 18
...Position detection sensor, 19...Control circuit, 20,
21...Up-down counter, 22...Counter, 23...Crystal oscillator, 24, 27...Digital-analog converter, (D/A converter), 25,
28...Phase compensation circuit, 26, 29...Amplifier,
30...Photoreceptor.

Claims (1)

[Claims for Utility Model Registration] A first driving means for driving an illumination system and a second driving means for driving an imaging system, the illumination system and the imaging system being driven by separate driving means. In the drive control device for the original exposure unit to be driven, a first
means for detecting distance traveled by the illumination system from when it is detected by the first means to a predetermined stop position; and disposed between the predetermined stop position and the exposure position. a second means for detecting the imaging system; and a second means for detecting the illumination system from a predetermined stop position based on the moving distance detected by the distance detecting means and the arrangement position of the second means. means for calculating a distance to be moved to an arrangement position of the illumination system and the imaging system from the predetermined stop position toward the exposure position, and the imaging system is driven by the second means. means for detecting a positional error between the illumination system and the imaging system at the time when the illumination system is detected; and means for driving and controlling the first or second driving means in accordance with the positional error detected by the detecting means so as to achieve phase synchronization with the document exposure unit. Control device.