JPS6250722A - Synchronizing device for photoscanning recording device - Google Patents

Abstract

PURPOSE:To make an image information recording position in each scan constant to an end surface of a recording medium and to obtain a stable recording image by correcting and controlling the time from the generation of a synchronizing signal to the start of image recording. CONSTITUTION:When a photodetector 7 detects a light beam reflected by a reflecting mirror 6 in the 1st light beam scanning, a synchronizing signal generating circuit 11 generates a signal. Then when the synchronizing signal is inputted to a recording control circuit 13, image information is supplied to a laser driving circuit 14 a set time (a) later and the circuit 14 generates a photoscanning beam to record a signal on a photosensitive drum 1. At this time, the end surface position of the recording medium 10 in a main scanning direction is detected by a position detector 8 as a reference position for subsequent scanning. In the 2nd and succeeding scanning operation, the quantity of variation of the recording medium 10 from the reference position is detected by a position detector 8 and a position detecting circuit 12 and inputted to the circuit 13, which corrects the time (a) according to the quantity of position variation after receiving the synchronizing signal from the circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical scanning recording device that forms an image, records information, etc. by scanning a scanned member with an optical scanning beam using a polarizer, etc. Properly control the start timing,
This invention relates to a synchronization device for stable recording.

2. Description of the Related Art Conventionally, as an optical scanning device of this type, an electrostatic latent image recording section of a laser image recording device shown in FIG. 6 has been known. In FIG. 5, the optical scanning beam L outputted by the semiconductor laser 2 is made into parallel light by the collimator lens 3, and then is sent to the rotating polygon mirror 4 in the axial direction of the photoreceptor drum 1 (hereinafter referred to as the main scanning direction). The light is polarized (scanned) and imaged onto the photoreceptor drum 1 by an f/θ lens 5. The optical scanning beam L output by the semiconductor laser 2 is modulated by an electrical signal (not shown), and the photosensitive drum 1 is rotated at a constant speed in the direction of the arrow (hereinafter referred to as the sub-scanning direction). An electrostatic latent image is formed two-dimensionally on the photosensitive drum 1. Incidentally, a developing and transferring means of a well-known electrophotographic process is arranged around the photosensitive drum 1, so that the electrostatic latent image described above is visualized on a recording medium such as a recording paper.

In such a configuration, in order to time the start of modulation of the optical scanning beam in the main scanning direction of the photoreceptor drum 1 for each scan and to accurately align the position of the recorded image area, there is a A reflecting mirror 6 is provided, and a photodetector 7 is provided at a position to receive the reflected light. When the optical scanning beam is incident on the photodetector 7, an optical beam scanning synchronization signal is generated. This synchronization signal causes the semiconductor laser 2 to The timing of the start of modulation at the start of image recording is controlled.

This original beam scanning synchronization signal is generally generated by comparing the output level of the photodetector 7 with a predetermined reference level and detecting the optical scanning beam. Note that by accurately obtaining this synchronization signal for each scan, the timing for starting image signal modulation can be determined accurately regardless of the precision of the surface division angle of the rotating polygon mirror 4 and the unevenness of the rotation speed. can be precisely matched for each scan, it is necessary to detect the optical scanning beam with extremely high precision and generate a synchronization signal. One method of controlling the image signal modulation start timing using the synchronization signal is to count clocks of a constant frequency using the synchronization signal, and when the count reaches a constant number, that is, when the optical scanning beam L is This is a control method in which image signal modulation is started only when the image signal passes through the detector 7 and reaches the image recording start position L7.

Another method is to provide a timer including a time constant circuit instead of a counter so that the image signal modulation is started after a certain period of time that is the same as the time for counting a certain number of clocks, and a similar effect can be obtained. It's something you get. In these methods, by changing the count value of the counter and the time constant of the timer, it is possible to selectively define the image recording start position according to the recording paper size and the like.

Problems to be Solved by the Invention However, with this configuration, even if the optical scanning beam L is detected extremely accurately by the photodetector 7 and the timing of starting image recording is made the same for each scan, the recording medium If the sheet is bent (diagonally conveyed) or laterally shifted due to a problem with the paper conveyance system, the image formed based on a fixed recording timing will also shift with each scan. This will be explained using FIG. The optical scanning beam polarized (scanned) in the main scanning direction is detected by the photodetector 7 in FIG.
Since image recording starts after a certain period of time after the recording medium is incident on the photodetector 7, the recording medium (B) is recorded at the same distance from the photodetector 7 for each main scan. When the position of the recording dots changes in the main scanning direction with respect to the mounting position 7, as shown in Figure 6, when viewed on the recording medium, the recording dots change in the main scanning direction according to the amount of positional fluctuation of the recording medium. This results in a deviation amount ΔK, and the recorded image is shifted.

To deal with this problem, we have developed a system to solve the problem of positional deviation (skew, lateral shift, etc.) during the movement of the recording medium in the main scanning direction, which records images according to image information, and fluctuations in the recording position due to expansion and contraction of the recording medium.
It is thought that the misalignment of the recorded dots can be prevented by eliminating it mechanically, but in reality, the misalignment of the recorded dots is regulated with very high precision, and precision on the μm level is required. Therefore, it is extremely difficult to prevent paper misalignment to that extent using mechanical methods. Also,
When recording an image multiple times on a single recording medium using a color laser image recording device, etc., and recording a color image by overlapping multiple colors, for each recording,
In order to mechanically match the recording position on the paper every time, a very complicated mechanism is required, which has the drawback of increasing costs.

The present invention has been made in view of the above-mentioned problems, and is a synchronization device for an optical scanning recording device that can always record a stable image without distortion in the recorded image even if the recording medium is misaligned. The purpose is to provide

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a photodetector that detects an optical scanning beam for each scan, and an output from the photodetector for each scan of the optical scanning beam. means for generating a synchronization signal as a reference for starting scanning; means for detecting the amount of position variation in the polarization direction of the optical scanning beam of the recording medium; and means for detecting image information from the generation of the synchronization signal based on the amount of position variation. The apparatus also includes means for correcting the timing until recording is performed.

Effect of the Invention With the above-described configuration, the present invention can detect the amount of positional variation of the recording medium in the main scanning direction, and correct the time from the generation of the synchronizing signal to the start of image information = 1 recording based on the detected amount of variation. , it is possible to prevent misalignment of the first position. In this way, even if the recording medium moves in the main scanning direction with respect to the photodetector from the main scanning start position of the first line due to various reasons, the time from synchronization signal generation to the start of image information recording or reading will be maintained. The time is corrected for each scan according to the variation.

Example Hereinafter, preferred embodiments of the present invention will be described.

FIG. 1 is a schematic configuration diagram showing a laser image recording apparatus according to an embodiment of the present invention, and the same members as those shown in FIG. 6 are designated by the same reference numerals and detailed explanations will be omitted.

In FIG. 1, 8 is a position detector using an optical sensor. 9 is a position detection mark, and 1o is a recording medium. The position detection mark 9 is located on the recording medium conveyance path.
The photoreceptor drum 1 is placed as close to the photoreceptor drum 1 as possible, and is made of a material that is black or has a different color from the recording medium so that the recording medium 10 does not touch the mark. Any method may be used as long as it does not affect the running of the recording medium, even if the recording medium is passed through the recording medium, and a method of simply coloring the recording medium transport plate or the like may be used. The position detector 8 constantly detects the edge portion of the recording medium 1o based on the difference in reflectance between the recording medium 10 and the position detection mark 9 when the recording medium 1o passes over the position detection mark 9. However, the amount of positional fluctuation of the recording medium 10 in the main scanning direction of the optical scanning beam is detected.

FIG. 2 is a diagram showing a schematic configuration of a circuit of a laser image recording apparatus according to an embodiment of the present invention. Reference numeral 11 denotes a synchronization signal generation circuit, which receives a detection signal of the optical scanning beam from the photodetector 7 and generates a synchronization signal for synchronizing the timing of the start of image information recording for each scan. Note that the photodetector 7 includes
A photodiode capable of high-speed response is used, and is designed to exhibit high sensitivity to the oscillation wavelength of the semiconductor laser 2. 12
1 is a position detection circuit, which detects the amount of positional variation in the main scanning direction of the recording medium 1o based on the output signal from the position detector 8. Reference numeral 13 denotes a recording control circuit, which stores in advance the amount of correction for the image information recording start timing based on the amount of positional fluctuation of the recording medium 10 in the main scanning direction, and uses the synchronizing signal from the synchronizing signal generating circuit 11 to control the position. Detection circuit 1
2, selects the stored correction amount for the recording start timing based on this position detection signal, and determines the time required to start image information recording based on the specified correction amount. It is configured to be able to be automatically set stepwise or continuously, and by this setting, the timing from generation of the synchronization signal to recording of image information is corrected.

The recording control circuit 13 is composed of a general counter or timer, and its count value or time constant value can be controlled and selected from the outside. Reference numeral 14 denotes a laser drive circuit, which is configured to turn on and off the input current to the semiconductor laser 2 in accordance with a recording signal sent from the recording control circuit 13. This laser drive circuit 1
4 uses, for example, a known current circuit.

15 is an image information input section. The image signal sent to the image information input unit 15 is synchronized by the recording control circuit 13 with respect to the recording start position and the timing of its modulation start for each scan, and is sent to the laser drive circuit 14, and is then sent to the laser drive circuit 14. An image is formed on the body drum 1.

FIG. 3 is a diagram illustrating the output waveform from the position detector 8, and shows the value of the output voltage of the position detector 9 at the light receiving sensor position corresponding to the polarization direction of the optical scanning beam. The output waveform has a shape divided into an area of the recording medium 1o where output voltage is generated and an area of the position detection mark 9 where almost no output voltage is obtained, as shown in waveform A and waveform B. The intermediate position (falling position of the output voltage) E, , E2 is the recording medium 1 in Fig. 2.
This corresponds to the end surface of o in the main scanning direction. Therefore,
When the position of the recording medium 1o changes in the main scanning direction, the output waveform of the position detector 8 changes as shown in waveform B, and the falling position changes, so by comparison with a fixed detection level, , IC2 is detected at the sensor position corresponding to the absolute position of the end face of the recording medium 10, and from the respective output signals, the position detection circuit 12 detects the recording medium 1Q.
The amount of deviation in the main scanning direction is detected.

Next, the operation of the above embodiment will be explained with reference to the main signal waveform diagram shown in FIG. First, in the first light beam scan, when the photodetector 7 detects the light beam reflected by the reflecting mirror 6, the synchronization signal generation circuit 11 generates the synchronization signal shown in FIG. 4(A). Since it is necessary to generate this synchronization signal with extremely high precision, accurate detection is performed using a sampling circuit using a high-frequency clock or a sampling circuit using a multiphase clock whose phase is slightly shifted by a delay circuit or the like. When the synchronization signal is input to the recording control circuit 13, as shown in FIG.
After that, the laser drive circuit 14
As shown in FIG. 2, an optical scanning beam modulated according to image information is generated to perform recording on the photoreceptor drum. At this time, the position of the end surface of the recording medium 10 in the main scanning direction (referred to as KO) is detected by the position detector 8, and is used as a reference position for detecting the amount of positional variation of the recording medium 1o during subsequent scanning. .

In the second and subsequent scans, the position detector 8 and the position detection circuit 12 detect the amount of variation from the reference position of the recording medium 10 and input it to the recording control circuit 13.
3 corrects the delay time (FIG. 4 (mouth 1 time a) from receiving the synchronizing signal from the synchronizing signal generating circuit 11 to starting image recording according to the amount of positional variation. That is, When the end face position of the recording medium 1° is at position E, which corresponds to the output waveform in Figure 3, after the synchronization signal shown in Figure 4) is generated, the preset time until the start of recording is The delay time a is calculated according to the amount of fluctuation (Eo-1,) of the recording medium.
After the time has elapsed, record as shown in (). Similarly, when the end surface position of the recording medium 1o is at the position E2 corresponding to the output waveform B in FIG. 3, the delay time from the generation of the synchronization signal shown in (G) in FIG. is corrected to the time C shown in (G) according to the fluctuation t (go IC2), and after the elapse of time C, (W)
Record as shown. Here, the correction according to the amount of variation in the recording medium 10 is determined so that the recording start position is always at the same position from the end surface of the recording medium for each scan.

In this way, a surface image is recorded on the photosensitive drum at a constant position from the end surface of the recording medium. Note that the time from the generation of the synchronization signal to the start of recording (time (a) in Figure 4 (b)
t can be controlled automatically or manually from the outside in order to reduce the mechanical viscosity of the arrangement of the photodetector 7 and reflector 6 relative to the photosensitive drum 1, and to change the distribution start position depending on the recording size. As a result, the above-mentioned correction is further added to the set time.

The electrostatic latent image formed on the photosensitive drum shown in FIG. 1 is visualized by a developing device (not shown), and then transferred onto the recording medium 10 to finally become a recorded image. At this time, the end position of the recording medium may shift in the main scanning direction due to skew or misalignment with respect to the photoconductor drum 1, but as described above, the image formed on the photoconductor drum 1 Since the image is controlled for each scan so that it is at a constant position from the edge of the medium, the image transferred to the recording medium is good and free of distortion.

In the above embodiment, the end face position of the recording medium detected during the first scan is used as the reference position, and thereafter, the amount of variation from the reference position is detected, and correction is performed according to the amount of variation. However, the present invention is not limited to this, and a reference position may be set in advance and the amount of variation from the reference position may be always detected. Further, although the position detector 8 is placed on the image information recording start side of the recording medium 10, the position detector 8 is not limited to this, and may be placed on the image information recording end side. In addition, when several sizes of recording media are selected, the position detection mark 9 is lengthened in the main scanning direction until it can accommodate each size, and the position detector 8 is adjusted according to the size of the recording medium. If the scanner is made movable close to the edge of the recording medium, it is possible to perform similar scanning for recording images on recording media of various sizes.

Further, in the above embodiment, a laser image recording device based on a well-known electrophotographic process is illustrated, but the present invention is not limited thereto, and can be applied to any image recording device using an optical scanning beam. is also applicable.

Effects of the Invention As is clear from the above description, the present invention achieves synchronization according to the output signals from the means for generating a synchronization signal based on the output signal of the photodetector and the means for detecting the amount of positional variation in the main scanning direction of the recording medium. By correcting and controlling the time from signal generation to the start of image information recording, the start of image information recording for each scan can be made constant with respect to the end surface of the recording medium.
This has the effect that there is no image shift for each scan, and a stable distributed image can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an electrostatic latent image forming section of an optical scanning distribution device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing its circuit configuration, and FIG. A waveform diagram showing the output of the position detector, FIG. 4 is a waveform diagram of main parts of the above embodiment,
FIG. 5 is a perspective view showing a schematic configuration of an electrostatic latent image forming section of a conventional laser image e-recording device, and FIG. 6 is a schematic diagram showing an example of a conventional image recording device. 1... Photosensitive drum, 2... Semiconductor laser, 4... Rotating polygon mirror, 6... Reflecting mirror, 7... Light Detector, 8...Position detector, 9...Position detection mark, 10...
・Recording medium, 11... Synchronization signal generation circuit, 12
...Position detection circuit, 13...Record control circuit, 14...Laser drive circuit, 15...
...Picture signal input section, A. B...Position detector output waveform. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
4th diagram 1 (AY) ゛<U) f Figure 6 AT:

Claims (1)

[Claims] means for scanning an optical scanning beam modulated according to image information over a member to be scanned by a polarizer to form a latent image on the member to be scanned; a transfer means for transferring onto a recording medium supplied so as to be in contact with a scanning member; a photodetector for detecting the optical scanning beam for each scan; and scanning by an output from the photodetector for each scanning of the optical scanning beam. means for generating a synchronization signal serving as a starting reference; means for detecting a positional variation in the polarization direction of the optical scanning beam of the recording medium; and based on the positional variation,
A synchronization device for an optical scanning recording apparatus, comprising means for correcting timing from generation of the synchronization signal to recording of image information.