JPS6081965A - Scanning device - Google Patents

Abstract

PURPOSE:To prevent influence of jitter of a motor automatically and to facilitate adjustment of a scanning device by counting scanning start pulse period sections, reading the counted value by a jitter correcting circuit, calculating the deviation and correcting sampling frequency for each face. CONSTITUTION:Laser light from the scanning light source 3 of a scanning device is irradiated onto the face 17 of an original through a rotary multilateral mirror 1, a lens 15 and a photoelectrical conversion mirror 16. Scanning start pulse from a scanning start pulse generator 7 and scanning area information of a scanning face discriminating circuit 9 are inputted to a phase section counter 19, phase section of each face of the multilateral mirror 1 is counted by output of a reference pulse generator 18, and the counted value is added to a CPU10. This is compared with a reference counted value read out from an RAM12 by the CPU10, and correction value for sampling frequency is calculated. The correction value is added to a sampling pulse generator 6, and correction for each face of the multilateral mirror 1 is made. Thus, influence of jitter of a main scanning motor is prevented automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning device, and more particularly to a scanning device having a main scanning motor jitter correction device used in a flat scanning facsimile scanning device.

A conventional scanning device of this type will be explained with reference to FIG. FIG. 1 is a block diagram showing an example of a conventional scanning device. In the figure, a laser beam from a scanning light source 3 passes through a collimating lens 14 and is irradiated onto the reflective surface of a rotating polygon mirror 1 that is rotated at a constant speed by a main scanning motor (hereinafter referred to as M) 2. is reflected along a reflection path that follows the direction of rotation (illustrated by the curved arrow). This reflected light is fθ
The light passes through the lens 15 and is reflected by the optical path converting mirror 16 and is irradiated onto the scanning start pulse generator 7 and the document surface 17.
Reflected light from the document surface 17 is inputted to the photoelectric conversion circuit 4 . The writing signal converted into an electric signal by the photoelectric conversion circuit 4 is sampled at a predetermined time interval by a sampling circuit (hereinafter referred to as SMP), and further converted into digital information, and then inputted to a display (hereinafter referred to as CRT) 13 and displayed on CR, T. is reproduced as a visible image. Scanning plane identification circuit (hereinafter referred to as PH)
8) In 9, the rotational phase pulse from the rotational phase pulse generator 8 and the scan start pulse from the scan start pulse generator 7 are input manually, and it is identified which surface of the rotating polygon mirror 1 is responsible for the scan start pulse. The scan plane information is then output to a jitter correction circuit (hereinafter referred to as CPU) 10 constituted by a microprocessor. The CPU10 follows the scanning surface information from the PH89 at the time when Ml reaches synchronous rotation before scanning the original,
The correction values corresponding to each surface of the co-rotating polygon mirror 1 are read from the switch board (hereinafter referred to as 5W) 11, and the sampling frequency uniquely determined by the rotational speed of M2 and the sampling density of the original surface 17 is calculated and then corrected. do. The sampling frequency corrected corresponding to each surface of the rotating polygon mirror 1 is temporarily stored in a data memory (hereinafter referred to as RAM) 12. When scanning of the original surface 17 actually starts, the CPU
O follows the scanning plane information from the PH89 and synchronizes with the scanning start pulse from the scanning start pulse generator 7.
A sampling frequency corrected corresponding to each surface of the rotating polygon mirror 1 is read out from M12 and outputted to a sampling pulse generator (hereinafter referred to as O8C) 6.

osc, 6 generates a sampling pulse according to this sampling frequency designation signal from CPU10 (8M1)
In addition to outputting to C1IT13, a signal defining the effective range of the drawing signal in the main scanning direction is outputted to C1IT13. Note that switches corresponding to each surface of the rotating polygon mirror 1 are mounted on the 5WII, and the most significant bits can specify + and -, and the lower 7 bits can set a percentage of the sampling frequency. Therefore, the adjuster looks at the visible images reproduced in CR and T, determines the amount of jitter on each surface of the rotating polygon mirror 1, and adjusts the switches so as to obtain the optimum image.

As described above, conventional scanning devices have the drawback of lacking exact accuracy because the adjustment work is subjective and complicated based on the eyes of the adjuster.

The purpose of the present invention is to digitally measure the scanning speed on each surface of a rotating polygon mirror, determine the deviation value (amount of jitter), and automatically process jitter correction to calculate the sampling frequency that minimizes this. The object of the present invention is to provide a scanning device which eliminates the above-mentioned drawbacks and can quickly and accurately correct the jitter of a main scanning motor.

According to the present invention, there is provided a rotating polygon mirror, a main scanning motor that rotates the rotating polygon mirror at a constant speed around a rotation axis, and a main scanning motor that continuously changes the direction of light reflected by the rotating polygon mirror by the constant rotation. a scanning light source for generating scanning light that scans a document surface; a photoelectric conversion circuit that photoelectrically converts the reflected light to obtain a calligraphy signal; a sampling circuit that samples the calligraphy signal at a predetermined period; and an input to the sampling circuit. a sampling pulse generator that generates sampling pulses to be scanned and whose oscillation frequency can be changed by an external frequency designation signal; a scan start pulse generator that generates a scan start pulse in response to the scan start timing of the document surface by detecting scanning light prior to scanning the document surface; and a scan start pulse generator that is attached to the rotation shaft of the main scanning motor. a rotational phase pulse generator that outputs a rotational phase pulse synchronized with the rotation period of the main scanning motor; and a rotational phase pulse generator that outputs a rotational phase pulse synchronized with the rotational period of the main scanning motor; The main scanning motor jitter correction device includes a reference pulse generator that generates a reference pulse that serves as a reference for generation synchronization measurement of the scanning start pulse, and a counter for counting the reference pulse within a period interval of the start pulse; and a counter for counting the reference pulse within a period interval of the start pulse; and a counter for counting the reference pulse within the period interval of the start pulse; a scanning surface identification circuit that identifies which surface is caused by the scanning surface and outputs scanning surface information in synchronization with the scanning start pulse; and a jitter correction circuit that corrects the oscillation frequency of the sampling pulse generator by determining the deviation value of the scanning speed on each plane and calculating the frequency of the sampling pulse that minimizes the deviation value. A scanning device is obtained.

Next, the present invention will be explained with reference to FIG.

FIG. 2 is a block diagram showing an embodiment of the scanning device of the present invention. In the figure, parts having the same configuration and functions as those of the conventional scanning device are given the same reference numerals as in FIG. 1. This example is based on a conventional example (shown in Figure 1).
is deleted, and a reference pulse generator (hereinafter referred to as 08C1
) 18 and a phase interval counter (
Hereinafter, CNT) 19 is added.

Next, the operation of this embodiment will be explained. The operation from the time when the laser beam from the scanning light source 3 irradiates the document surface 17 until the scanning surface information is obtained by the PH 89 is the same as that shown in FIG. 1, and therefore the description thereof will be omitted. The scan start pulse from the scan start pulse generator 7 and the scan surface information from the PH89 are input to the CNT19, and the phase interval of each surface of the rotating polygon mirror 1 is counted using the reference pulse from 08Ct18, and the counted value is calculated. Output to CPU10. The CPU 1o stores in the RAM 12 a calculated value calculated using a reference pulse within a phase interval that is uniquely calculated from the rotation speed of M2 and the sampling density of the document surface 17, and stores the calculated value read out from the RAM 12 and the calculated value. A correction value for the sampling frequency is calculated by comparing the count value of the CNT 19 output. For example, if the count value of the phase interval is smaller than the calculated value, the phase interval is short, and the sampling frequency is corrected by calculating a correction value toward the faster sampling frequency. Tilt it so that the numbers fit.

This makes the number of sampling pulses within the phase interval uniform, thereby eliminating the influence of jitter within the phase interval. The sampling frequency of each surface of the rotating polygon mirror 1 corrected in this way is stored in the RAM 12. When the scanning of the original surface 17 actually starts, the CPU 10 executes the RAM 12 in accordance with the scanning surface information from the PI-189 and in synchronization with the scanning start pulse from the scanning start pulse generator 7.
Jitter correction is performed by outputting a sampling frequency corrected corresponding to each surface of the rotating polygon mirror 1.

As explained above, in this embodiment, by automatically correcting the sampling pulses so that the number of sampling pulses within the phase interval is constant, the influence of jitter of the main scanning motor can be eliminated, and the digital Since processing is performed, correction can be performed accurately and quickly.

As explained above, the scanning device of the present invention is configured to count the scan start pulse period section, read the counted value by the jitter correction circuit, calculate the deviation, and correct the sampling frequency for each surface. This has the effect of automatically, quickly and accurately preventing the influence of jitter of the main scanning motor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional scanning device, and FIG. 2 is a block diagram showing an embodiment of the scanning device of the present invention. In the figure, 1... Rotating polygon mirror, 2...
・Main scanning motor (M), 3...Scanning light source, 4.
...Photoelectric conversion circuit, 5...Sampling circuit (SMP), 6...Sampling pulse generator (OSC,), 7...Scanning start pulse generation equipment, 8...--rotary phase pulse generator, 9...
...Scanning plane identification circuit (PH8), 10.,. ... Jitter correction circuit (CPU), 11 ... Switch board (SW), 12 ... Data memory i, AM), 13 ... Display (CRT,
), 14... collimating lens, 15...
...fθ lens, 16...Photoelectric conversion mirror, 1
7... Original drawing, 18... Basic pulse generator (OSC,), 19... Phase interval counter (
C.N.T.). Abandoned once

Claims (1)

[Claims] Rotating polygon mirror and rotating polygon mirror at constant speed around the rotation axis.
a scanning light source for generating scanning light that scans the document surface by continuously changing the direction of light reflected by the rotating polygon mirror by rotating at a constant speed; a photoelectric conversion circuit that obtains a signal; a sampling circuit that samples the calligraphy signal at a predetermined period;
a sampling pulse generator which generates a sampling pulse to be input to the sampling circuit and whose oscillation frequency can be changed by an external frequency designation signal; a scan start pulse generator that generates a scan start pulse in response to a timing to start scanning the document surface by detecting scanning light on each surface of the rotating polygon mirror prior to scanning the document surface; and the main scanning motor. A rotational phase pulse generator is attached to the rotational shaft of the main scanning motor to output a rotational phase pulse synchronized with the rotational period of the main scanning motor, and a rotational phase pulse generator is attached to the rotating shaft to control the scanning speed of each surface of the rotating polygon mirror due to the jitter of the main scanning motor. The main scanning motor jitter correction device includes a main scanning motor jitter correction device that corrects deviations in the sampling position on the document scanning surface due to deviations in the scanning direction, and the main scanning motor jitter correction device has a reference pulse that generates a reference pulse that is a reference for measuring the generation period of the scanning start pulse. a pulse generator; a counter for counting the reference pulses within a period interval of the scan start pulse; and a scan unit that inputs the scan start pulse and the rotational phase pulse and sequentially generates the scan in synchronization with the rotation of the main scan motor. a scanning surface identification circuit that identifies which surface of the rotating polygon mirror causes the start pulse and outputs scanning surface information in synchronization with the scanning start pulse; a jitter correction circuit that corrects the oscillation frequency of the sampling pulse generator by determining the deviation value of the scanning speed on each surface of the rotating polygon mirror from the output and calculating the frequency of the sampling pulse that minimizes the individual difference value; A scanning device comprising: