JPH04163434A - Traveling speed controller of optical system - Google Patents

Abstract

PURPOSE:To carry out highly accurate control and provide a better picture image by comparing a speed signal obtained through a process of integrating a signal from an acceleration sensor with a reference speed signal, and carrying out constant speed control based on the compared results. CONSTITUTION:Acceleration related to the movement of an optical system is detected by an accleration sensor 41e, and after the acceleration signal is converted into a speed signal V by a integration circuit F, it is inputted into a speed control circuit 8 to carry out constant speed of a motor 91 by the circuit 8. Namely, a deviation of the speed of the optical system obtained by the circuit F from a reference speed is detected, and voltage and current proportional to the deviation are given to the motor 91 to carry out feedback control so that speed deviation may be minimized. Consequently, any abnormality in the operation of the optical system is detected, and feedback control can be carried out so that traveling speed may always become constant, thus it is possible to prevent occurrence of copying failure in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a movement speed control device for an optical system of an electrostatic copying machine, a document reading device, or the like.

<Prior Art> In image processing devices such as electrostatic copying machines and document reading devices that illuminate and scan a document by relatively moving the document table on which the document is placed and an optical system, each part of the device ,especially,
If the optical system becomes unstable or if there is an abnormality in the operation of the drive member that moves the optical system relative to the main body of the device, the moving speed of the optical system will not be constant. This may adversely affect the formed or read image, resulting in image defects such as image blur and density unevenness.

In order to prevent the speed unevenness mentioned above, conventionally,
An optical encoder consisting of a disc with a slit and a photosensor was attached to the rotary motor that drives the optical system, and its output pulse signal was detected. Then, if the pulse period becomes unstable, the speed is controlled so that it becomes constant.

Alternatively, (2) a scale is placed in the optical system, its movement is observed using an optical sensor, and the speed of the optical system is detected from the observation pulse, which is fed back to the motor to perform constant speed control.

<Problem to be Solved by the Invention> However, since the technique (2) above detects pulses corresponding to the rotation of the motor, it is not possible to expect accuracy higher than the resolution determined by the pulse period and pulse width. Therefore, it was not possible to see subtle changes in the movement of the optical system, and there were limits to constant speed control.

Furthermore, with the technique (2) above, there is a limit to the length of the scale installed in the optical system, and it is not possible to observe over a long distance. The pulse width is also determined once the scale graduation width is determined, and the resolution cannot be made any finer.

This invention has been made in view of the above problems, and it is possible to more accurately detect subtle speed irregularities and perform accurate constant speed control, thereby preventing the occurrence of image defects. It is an object of the present invention to provide an optical system movement speed control device that can prevent such problems.

Means for Solving the Problems> In order to solve the above problems, the moving speed control device for an optical system of the present invention has an acceleration sensor fixed to the optical system, and integrates the output signal of the acceleration sensor. a calculation means for obtaining a speed signal; a storage means for storing in advance a reference speed during normal movement of the optical system; and a comparison of the speed calculated by the calculation means with the reference speed stored by the storage means for determination. The apparatus includes a determining means and a control means for controlling the rotation speed of a motor that drives the optical system based on the result of the determination.

In the optical system movement speed control device of the present invention having the above configuration, the movement of the optical system is directly and analogously detected by fixing an acceleration sensor to the optical system, and the obtained signal is The accurate speed of the optical system can be obtained by converting it into a speed signal using arithmetic means.

Further, the determining means compares the reference speed of the optical system during normal movement with the speed of the optical system calculated by the calculating means to check whether there is any deviation in speed.

The speed deviation is usually caused by, for example, a shift in the optical system or an abnormal operation of the motor, so when a speed deviation is detected by the discriminating means, the control means
Control the rotation speed to be constant.

In this way, it is possible to prevent image defects caused by changes in the speed of the optical system, even if the speed changes are subtle.

<Embodiments> Hereinafter, embodiments of the movement speed control device of the present invention provided in an electrostatic copying machine will be described with reference to the accompanying drawings.

As shown in FIG. 3, the electrostatic copying machine has a document table 2 on the top surface of the main body 1 for placing a document to be copied, and a document holding plate for keeping the document in close contact with the document table 2. 3, and an optical system 4 for illuminating and scanning the document placed on the document table 2 inside the main body of the apparatus, and a photoconductor tram 51 by exposing the document image by the optical system 4.
An image processing section 5 that visualizes the electrostatic latent image formed thereon using a developing device 52 and then transfers it onto a transfer paper;
The transfer paper is sent from the transfer paper cassette 61 to the image processing section 5, and the image-processed transfer paper is sent to the paper output tray 6 via the fixing means 7.
2, and a transfer paper conveyance section 6 for discharging the paper onto the paper.

The optical system 4 includes first and second movable members 41 and 42 that move relative to the device body 1, and optical elements fixed to the device body 1, as shown by white arrows and two-dot chain lines in the figure. 4
3 and a fixed mirror 44. Note that the first moving member 41 includes a lamp 41b for irradiating light onto the original placed on the original platen 2;
A reflecting plate 41c for guiding light from the original toward the document table 2, and a mirror 41d for guiding light reflected from the original to another moving member 42 are arranged. Further, two mirrors 42b and 42c are arranged on the second moving member 42 to guide the reflected light from the mirror 41c to the optical element 43.

As shown in FIG. 1, the two moving members 41 and 42 are slidably disposed on a sliding bar 11 and a sliding plate 12, respectively, which are fixed to the main body of the device, and are driven by a drive system. , is configured to move on the sliding bar 11 and sliding plate 12. Note that the drive system for moving the two moving members 41 and 42 may have a normal configuration consisting of a motor 91 (see FIG. 2) and a wire wound around the rotating shaft of this motor 91. or has been adopted.

An acceleration sensor 41e is attached to the first moving member 41. As the acceleration sensor 41e, for example, a piezoelectric type acceleration sensor using a piezoelectric element such as lead titanate or crystal, a servo type acceleration sensor using a spring and a weight, etc. can be used.

The detection signal from the acceleration sensor 41e is input to the speed control circuit 8 via the integrating circuit F, as shown in FIG. The integration circuit F integrates the output signal from the acceleration sensor 41e and converts it into a speed signal, and functions as a calculation means.

In addition, a filter circuit for cutting unnecessary noise signals may be inserted before the integrating circuit F.

The speed control circuit 8 includes a subtractor 81 and a subtractor 81 for comparing the output signal (1) from the integrating circuit F with a reference speed signal VO stored in the storage circuit 84 during normal movement of the optical system 4 and calculating the difference. It has a compensation circuit 82 that performs certain calculations (for example, proportional calculation, proportional integral calculation) based on the output signal of 81, and a surfo amplifier circuit 83 that supplies voltage and current including a control amount to the motor 91. The storage circuit 84 may be of any type as long as it derives the reference speed signal VO, and may be a constant voltage source, for example.

With the above configuration, acceleration related to the movement of the optical system 4 is detected by the acceleration sensor 41e, and the acceleration signal is converted into a speed signal V by the integrating circuit F, and then manually inputted to the speed control circuit 8. The control circuit 8 can control the motor 91 at a constant speed. That is, the deviation between the speed of the optical system 4 obtained by the integrating circuit F and the reference speed is detected, and a voltage and current proportional to the deviation are applied to the motor 91 to perform foot hack control so that the speed deviation is minimized. It is possible.

As described above, according to the optical system movement speed control device of this embodiment, an abnormality in the operation of the optical system 4 can be detected and feedback control can be performed so that the movement speed is always constant. It is possible to prevent defects from occurring. In particular, since we decided to use an analog detector called the acceleration sensor 41e and perform analog processing on the detection signal, the detection resolution is much higher than in the past when the detection signal was obtained from an optical encoder. As a result, even subtle changes in the movement of the optical system 4 can be detected with good sensitivity. Therefore, accurate and delicate control can be performed.

Note that this invention is not limited to the above embodiments. For example, although the above-mentioned embodiment shows an example of an electrostatic copying machine, the optical system movement speed control device of the present invention can also be applied to a document reading device, as described above. In the case of this document reading device, an acceleration sensor may be attached to a moving member equipped with a light receiving element that receives an exposed image and converts it into an electrical signal for recording.

In addition, various design changes can be made without changing the gist of the invention.

<Effects of the Invention> The moving speed control device for an optical system of the present invention is configured as described above, and compares a speed signal obtained by integrating signals from an acceleration sensor with a reference speed signal. Since constant speed control is performed based on the results, highly accurate control of the optical system can be performed. Therefore, even subtle image defects can be prevented from occurring, and better images can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing essential parts of a document table and an optical system in an electrostatic copying machine which is an embodiment of the optical system movement speed control device of the present invention, and FIG. FIG. 3 is a schematic diagram showing the internal configuration of the electrostatic copying machine. 4. Optical system, 41e. Acceleration sensor, 81 Differential device, 82. Compensation circuit, 83. Servo amplifier circuit, 91. Drive motor

Claims (1)

[Claims] 1. An optical system illuminates and scans a document placed on a document table;
In an image forming device that forms an image by guiding reflected light from a document to a photoconductor and transferring the image formed on the photoconductor to transfer paper, an acceleration sensor is fixed to the optical system, and an acceleration sensor is fixed to the optical system. a calculation means for integrating an output signal of the sensor to obtain a speed signal; a storage means for storing in advance a reference speed during normal movement of the optical system; and a storage means for storing the speed calculated by the calculation means. What is claimed is: 1. A moving speed control device for an optical system, comprising: a determining means for determining the speed by comparing it with a reference speed, and a controlling means for controlling the rotational speed of a motor that drives the optical system based on the result of the determination.