JPH0430663A - Recording data controller - Google Patents

Abstract

PURPOSE:To simplify the mechanism of an optical system and the mechanism of a scanning drive system by generating a pulse signal by frequency-mixing a pulse signal with a fixed frequency and a pulse signal with a variable frequency so as to generate the pulse signal and making the frequency of the pulse generated from a fixed frequency pulse generating circuit correspondent to the optical path length from a laser light source to photosensing body. CONSTITUTION:A data clock generating circuit consists of a fixed frequency pulse generating circuit 11, a variable frequency pulse generating circuit 12 and a mixer 13 the frequencies of the pulse signals and the frequency of the pulse generated from the fixed frequency pulse generating circuit 11 is made correspondent to the optical path length from a laser light source 21 to a photosensing body. Thus, the frequency of the data clock is selected properly to make accurately coincident with even pictures formed by a laser beam having different optical lengths. Moreover, the frequency of the pulse signal of a variable frequency is changed to select the frequency of the data clock to improve the accuracy in the case of adjusting the scanning length of one line scanned on a photosensitive body by the laser beam.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser recording device, particularly a multi-transfer type laser recording device that is equipped with a plurality of laser light sources and performs composite recording of recorded images of different colors on a single sheet of recording paper. The present invention relates to recording devices such as devices.

[Conventional technology]

2. Description of the Related Art In recent years, with the spread of digital copying machines, laser recording devices that record images on recording paper using an electrostatic photographic process by irradiating a photoreceptor with a laser beam according to image information have come into widespread use.

Figure 7 shows image formation using a laser light emitting element, 4
1 is a configuration diagram of a conventional full-color laser recording device equipped with a color image forming device (photosensitive drum, developing device, etc.); FIG. In the figure, 20 is an optical scanning device, 30 is an image processing unit that converts an image signal into a recording signal, 40 is an image forming device for four colors arranged in order along the conveyance direction of the recording paper, and 50 is a recording paper. 51 is a fixing roller that fixes the transferred toner image; 52 is a registration roller that synchronizes the leading edge of the recording paper; 53 is a paper feed roller that sequentially takes out the stocked recording paper; 54 is a recording paper that has been recorded. A paper discharge roller 55 discharges paper to the outside of the recording apparatus, and a paper feed cassette 55 stores recording paper.

In a full-color laser recording device, the color image to be recorded is yellow (Y), magenta (M), and cyan (C).
The colors are separated into Y, Y, and Y based on the respective image recording signals.
Single-color M and C images are sequentially formed on the same recording paper, and then superimposed to obtain a full-color image. However, in general, black (Bk) is used in addition to Y, M, and C to form a composite image using four colors. This corresponds to the black plate technique used in printing technology, and the use of Bk enables undercolor removal (UCR), which reduces toner consumption and the thickness of the recorded image coating, reducing the fixing load. This is because it has the advantage of reducing the

An image recording signal is input from the image processing section 30 to a laser driving section of the optical system for each color of Bk, Y, M, and C, and a signal-modulated laser beam BM is emitted from a semiconductor laser (not shown). The emitted laser beams BM each pass through a collimator lens and a cylindrical lens (not shown), are incident on the polygon mirror 25 of the deflector 24, and are deflected by rotation of the polygon mirror 25.
The light passes through the fθ lens 22, passes through a plurality of mirrors 23, is guided onto the photoreceptor drum 41, and scans the photoreceptor drum 41 for each color. Electrostatographic process units such as a charging charger 42, a developing device 43, a transfer charger 44, etc. are attached around each photosensitive drum 41, respectively. A latent image of a recorded image is formed on the photoreceptor 41 uniformly charged by the charger 42 by exposure to the laser beam BM, and the formed latent image is developed by the developing device 43 to become a developed image.

The leading edge of the transfer paper fed from the paper cassette 55 by the paper feed roller 53 is aligned by the registration roller 52, and transferred to the transfer belt 5 in synchronization with the movement of the developed image to the transfer section.
Sent to 0. The transfer paper conveyed by the transfer belt 50 is sequentially sent to the photoreceptor 41 on which a developed image is formed for each color of Bk, Y, M, and C, and the developed image is transferred under the action of the transfer charger 44. The transfer paper on which the developed image has been transferred is subjected to a fixing process by a fixing roller 51, and is discharged to the outside by a paper discharge roller 54.

In the optical system (reducing optical system) of such a recording device, the laser beam BM emitted from the semiconductor laser located behind the deflector 24 is converged in the direction of the rotating surface of the polygon mirror 25 via a collimator lens and a cylindrical lens. Polygon mirror 25 as laser beam BM
guided on the surface. The laser beam BM reflected by the surface of the polygon mirror 25 passes through the fθ lens 22 and the group of mirrors 23 and converges as a spot beam on the surface of the photoreceptor 41. Here, the laser beam BM for each color is subjected to multiple refraction using the 23 groups of mirrors.
This is to adjust the optical path lengths so that they are equal. This is because if the optical path length differs depending on the laser beam BM, the scanning length when the laser beam BM scans the photoreceptor 41 will differ even if the same lens system is used, resulting in color shift etc. in the composite recorded image. This is because the image quality deteriorates.

[Problem to be solved by the invention]

In the conventional laser recording device described above, due to the above circumstances, the optical path length of the laser beam from the laser light source to the photoreceptor must be adjusted to the longest optical path length even if it can be shortened. The mechanism of the system and the mechanism of the scanning drive system become complicated, and this is one of the factors that increases the size of the device. Although it is conceivable to use different lens systems to shorten the optical path length of the laser beam, using different lens systems would result in a significant increase in cost since the lens systems cannot be shared.

The present invention has been made based on the above-mentioned circumstances, and provides a laser recording device that simplifies the mechanism of the optical system and the mechanism of the scanning drive system in a laser recording device equipped with a plurality of photoreceptors each irradiated with a plurality of deflected and scanned laser beams. The purpose is to make it possible to reduce the size of the device.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides pixel synchronization in a recording data control device of a laser recording device equipped with a plurality of photoreceptors each irradiated with a plurality of laser beams emitted from a plurality of laser light sources. The data clock generation circuit that generates the data clock consists of a fixed frequency pulse generation circuit that generates a fixed frequency pulse signal, a variable frequency pulse generation circuit that generates a variable frequency pulse signal, and the pulse signals generated from these pulse generation circuits. The frequency of the pulse generated from the fixed frequency pulse generation circuit is made to correspond to the optical path length from the laser light source to the photoreceptor.

[Effect]

The data block generation circuit generates a pulse signal that is a frequency mixture of a fixed frequency pulse signal and a variable frequency pulse signal. As the optical path length from the laser light source to the photoreceptor increases, the frequency of the fixed frequency pulse signal also increases, and the frequency of the variable frequency pulse signal is changed to allow the laser beam to scan one line on the photoreceptor. Improve accuracy when adjusting length.

〔Example〕

Hereinafter, the present invention will be explained in detail based on one embodiment thereof.

FIG. 1 is a block diagram of the recording data control circuit of the laser recording apparatus of the embodiment, FIG. 2 is a block diagram of the data clock generation circuit of the recording data control circuit, and FIG. 3 is the variable frequency pulse generation circuit of the data clock generation circuit. 4 is a block diagram of a phase-locked loop (PLL) that constitutes the laser recording device, FIG. 4 is a block diagram showing a schematic configuration of the optical system of the laser recording device, and FIGS. 5 and 6 are explanatory diagrams showing the optical path of the laser beam BM, respectively. FIG. 3 is an explanatory diagram showing a state in which the optical path of the laser beam BM is virtually expanded on a plane.

In addition, in FIGS. 5 and 6, in order to avoid complication, only the left part of the optical system is shown, and the lens system is omitted. Also,
The same parts as in the conventional example of the device are given the same reference numerals.

In this embodiment, as shown in the configuration diagram of FIG. 4 showing the schematic configuration of the optical system of the laser recording device, the laser beam BM reflected and deflected by the polygon mirror 25 is bent by the mirror from the horizontal direction to the vertical direction. It is bent only at 23. Therefore, unlike the conventional example, there is no second and third mirrors for adjusting the optical path length of the laser beam BM, so the mechanism of the optical system including the scanning drive system is greatly simplified, and the recording device can be made smaller. is also possible. However, as shown in FIGS. 5 and 6, the optical path of the laser beam BM is divided into a laser beam BM-A reflected by the upper polygon mirror 25 surface and a laser beam BM-A reflected by the lower polygon mirror 25 surface. Beam BM-B will have different optical path lengths.

When such an optical system is used, if the data clock and lens system for determining the deflection magnification of the laser beam BM-A and the laser beam BM-B are shared as described above, the laser beam BM is directed to the surface of the photoreceptor 41. Scan above 1
The scanning lengths of the lines are different, making it impossible to obtain an appropriate composite image. Therefore, in the present invention, the data clock that provides pixel synchronization of image data is adjusted for each color, and one line that the laser beam BM scans on the surface of the photoreceptor 41 is adjusted. so that the scan lengths of

A recording data control circuit of a laser recording apparatus will be explained with reference to FIG. A beam detection pulse SPD emitted from an optical sensor provided to precisely match the dot phases between scanning lines is input to a data clock generation circuit 1, and a data clock CLK with the same phase is output. The data clock CLK is input to the main scanning counter 2, and the dot address is determined. The main scanning sequence is determined by the main scanning sequence circuit 3 based on the address of each dot with recording start at address O, and the entire one line scanning is controlled.

On the other hand, the image data D is input to the data synchronization circuit 5 via the receiver driver 4, and is synchronized with the image clock XCLK, which is also input from the external device to the data synchronization circuit 5 via the receiver driver 4. The data is read into the buffer memory 6. The data clock CLK is also input to the line buffer memory 6 and the data synchronization circuit 7, and provides synchronization timing when reading image data.

Video data V I DEO output in synchronization with the data clock CLK by the data synchronization circuit 7 is provided to a laser diode (LD) drive circuit 8 . The LD drive circuit 8 turns on the LD according to the video data VIDEO.
Lights off or lights up in intensity. The modulated laser beam BM emitted from the LD is irradiated onto the photoreceptor 41 to form a latent image of a recorded image.

In the recording data control circuit, when the frequency of the data clock CLK output from the data clock generation circuit 1 is changed, the do//) rate in the main scanning direction is changed. That is, the deflection magnification in the main scanning direction can be controlled by the frequency of the data clock CLK.

FIG. 1 shows the data clock generation circuit 1, in which 11 is a variable frequency pulse generation circuit (VO5C), 12
13 is a fixed frequency pulse generation circuit (FO3C), and 13 is a mixer (MIX) that outputs a pulse signal obtained by mixing the frequencies of the pulse signals output from these pulse generation circuits. If the frequencies of the pulse signals output from the variable frequency pulse generation circuit 11 and the fixed frequency pulse generation circuit 12 are fv and f, respectively, then the mixer 13 to which these pulse signals are input has a frequency of f=fV+ff. A pulse signal is output. By configuring the data clock generation circuit 1 in this manner, the frequency of the output data clock CLK can be stabilized. Further f
The larger the t/f vO value, the higher the data clock CLK.
frequency stability increases.

Therefore, the frequency of the data clock CLK that synchronizes the pixel data of the laser beam BM-A, which has a longer optical path length than the BM-B shown in FIGS. 4 to 6, must be set to a higher frequency, but fixed frequency pulse generation By setting the frequency f of the pulse signal output from the circuit 12 relatively large, the operation of the variable frequency pulse generation circuit 11 composed of, for example, a PLL is stabilized, and the data clock C
LK frequency fluctuation (jitter) can be reduced.

The variable frequency pulse generation circuit 11 and the fixed frequency pulse generation circuit 12 are, for example, a crystal oscillator and a PL, respectively.
It can be composed of L.

The PLL has a circuit configuration shown in the block diagram of FIG.
A pulse signal with a frequency fO output from the oscillator (OSC) 15 is input to a phase comparator (PD) 161, and the phase is compared with the output feedback signal fB of the PLL 16, which is input via a frequency divider (DIV) 164. . The comparison output from the PD 16 is input to a voltage controlled variable oscillator (VCO) 163 via a low pass filter (LPF) 162. The VCO 163 outputs an oscillation signal with a frequency corresponding to the comparison output. PLL16 has an oscillation pulse signal of frequency fO and DIV1
64 to eliminate the frequency and phase difference with the output feedback signal divided by l/N, and the frequency becomes fv=fOx
N stable clock signals are output. DIV164
Since the frequency division ratio N input to the circuit can be arbitrarily selected, the output clock signal fv can also be set to an arbitrary frequency.

〔Effect of the invention〕

As described above, according to the present invention, in a recording data control device of a laser recording device equipped with a plurality of photoreceptors each irradiated with a plurality of laser beams, a data clock generation circuit is replaced with a fixed frequency pulse generation circuit and a variable frequency pulse generation circuit. It consists of a pulse generation circuit and a mixer that mixes the frequency of the pulse signal, and the frequency of the pulse generated from the fixed frequency pulse generation circuit is made to correspond to the optical path length from the laser light source to the photoreceptor, so that the data clock By appropriately selecting the frequency, even images formed by laser beams having different optical path lengths can be made to match accurately. In addition, since the length of the optical path corresponds to the frequency of the fixed frequency pulse signal, the frequency of the variable frequency pulse signal is changed to select the frequency of the data clock, and the laser beam scans the photoreceptor. The accuracy when adjusting the scanning length of one line can be improved.

[Brief Description of the Drawings] Fig. 1 is a block diagram of the recording data control circuit of the laser recording device of the embodiment, Fig. 2 is a block diagram of the data clock generation circuit, Fig. 3 is a block diagram of the phase-locked loop, and Fig. 3 is a block diagram of the data clock generation circuit. 4
The figure is a block diagram showing the schematic configuration of the optical system of the laser recording device, and FIGS. 5 and 6 are explanatory diagrams showing the optical path of the laser beam, respectively, and the state in which the optical path of the laser beam is virtually expanded on a plane. The explanatory diagram shown in FIG. 7 is a block diagram of a conventional full-color laser recording apparatus. DESCRIPTION OF SYMBOLS 1...Data clock generation circuit, 11...Variable frequency pulse generation aO*1.12...Fixed frequency pulse generation circuit, 13...Mixer, 16...PLL, 20...
- Optical scanning device, 40...imaging device. To, sect

Claims (1)

[Claims] A laser recording device comprising a plurality of laser light sources, a deflector that deflects a plurality of laser beams emitted from the plurality of laser light sources, and a plurality of photoreceptors each irradiated with a laser beam deflected and scanned by the deflector. In the recording data control device of the device, a data clock generation circuit that generates a data clock that synchronizes pixels is divided into a fixed frequency pulse generation circuit that generates a fixed frequency pulse signal and a variable frequency pulse generation circuit that generates a variable frequency pulse signal. circuit, and a mixer that mixes the frequencies of the pulse signals generated from these pulse generation circuits, and the frequency of the pulses generated from the fixed frequency pulse generation circuit is
A recording data control device characterized in that the recording data control device corresponds to the length of an optical path from a laser light source to the photoreceptor.