JPS59123368A - Recorder - Google Patents

Abstract

PURPOSE:To decrease the recording time and to simplify the constitution by making the sequence of read of a picture signal to the 1st and the 2nd laser beams opposite to each other in order and making the scanning direction of the 1st and the 2nd laser beams opposite to each other. CONSTITUTION:A laser unit 10 includes a laser element and a drive circuit. The laser light 31 modulated depending on a picture signal and made in a parallel light by a collimeter lens 11 is scanned by a rotary polygon mirror 22 turned by a high speed rotating motor 21. This laser light is reflected on a reflecting mirror 41 and irradiated on a photosensitive drum 51. The drum 51 is turned at a low speed in the direction of an arrow and the recording paper is carried in the direction from the drum 51 to a drum 54. Since the direction of scanning of the photosensitive drums 51 and 52, 53 and 54 is opposite to each other, the signal is inputted to a drive circuit to the drums 52 and 54 so that the sequence of output of the color picture signal at each line is made opposite via an electric memory for 1-several lines' share.

Description

DETAILED DESCRIPTION OF THE INVENTION The technical field of the invention relates to a recording apparatus that forms images on a plurality of recording bodies using a laser beam.

Prior Art In a recording device such as a laser beam printer using the conventional Kameko photography method, a laser beam modulated by an image signal is reflected by a rotating prism or reflecting mirror (hereinafter referred to as a skier) to form a recording medium. Image formation is performed by running the photoreceptor over an electrophotographic photoreceptor. In this case, a drum-shaped photoreceptor is often used. When applying this method to a color printer, it is necessary to superimpose multiple images of different colors on recording paper. The main configurations for achieving this superimposition technology are as follows.

In one configuration, a first color image signal is scanned onto a photosensitive drum to create a latent image, a developer is applied for visualization, this is transferred to recording paper, and the TE optical drum is then cleaned. Then, scan the second color image signal onto the same photosensitive drum again! Create a kidney image and perform the same steps as the first step 1, except that a developer of the second color is used. The same process is repeated for the third color image signal and the fourth color image signal. In this way, one image is recorded by superimposing the developed image on the same recording paper multiple times.In another configuration, the same number of photosensitive drums are provided for multiple image signals. Then, a latent image is formed on a photosensitive drum in one-to-one correspondence with each color image signal, a latent image is developed using a developer of a different color, and then sequentially transferred to recording paper. In this case, it is common to prepare one laser, one scanner, and one photosensitive drum for one image signal, so if there are multiple image signals to be superimposed.

+1+i A'4 requires the same number of lasers, the same number of scanners, and the same number of photosensitive drums as the signals. The first configuration performs a series of electrophotographic processes of charging, exposing, developing, transferring, and cleaning on a first color image signal, and then performs a series of electrophotographic processes on a first color image signal.
The same process must be performed again on the color image signal, the third color image signal, and the fourth color image signal, respectively, in time series. Therefore, 1
The disadvantage is that it takes a very long time to print each sheet. Does the second configuration print faster than the first configuration? However, as mentioned above, it is necessary to prepare the same number of lasers, scanners, and drums as the number of color image signals for each color image signal, which has the disadvantage that the apparatus becomes large and expensive.

Normally, the printing time of laser printers can be shortened by increasing the rotation speed of the scanner. The conventional scanner rotation speed of a laser printer is 2
High speed rotation of 000 rpm to 20000 rpm is common. Furthermore, the prisms or mirrors used in skivners are polygonal mirrors (usually octahedral)9, and errors in the deflection angle can cause positional variations on the photosensitive drum depending on the optical path length of the laser beam. It is necessary that the fall error of each surface is very small, specifically within a few seconds, and it is also necessary that vibrations due to high detours be as small as possible. Therefore, the motor must be large in order to rotate the polygon mirror at high speed, and precision processing technology is required in the scanner manufacturing process because it is necessary to limit the tilting error of each mirror surface. For this reason, the manufacturing yield is poor and the product is very expensive.

The present invention addresses the above points, and provides a recording device that can simplify the configuration and shorten the recording time when recording images by scanning a plurality of recording bodies with a plurality of laser beams. The purpose is to provide equipment.

A further object of the present invention is to provide a recording apparatus in which the reading order of image signals for the plurality of laser beams is reversed when a plurality of recording bodies are scanned with a plurality of laser beams to form images.

EXAMPLES Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a first embodiment based on the present invention. 10 is a laser unit including a laser element and its drive circuit, and 11 is a collimator lens for collimating the laser beam. Modulated according to the image signal,
Laser light 3 becomes parallel light with collimator lens 11
1 is scanned by a rotating polygon mirror 22 that is rotated by a high-speed rotation motor 21. The scanned laser beam passes through a reflecting mirror 41
The light is reflected and irradiated onto the photosensitive drum 51. Around the photosensitive drum 51, there are provided a charging device, a developing device, a transfer agent for recording paper, a cleaning device, etc. necessary for electrophotography, which will be obvious to those skilled in the art. Therefore, in order to prevent the drawing from becoming complicated, these are omitted in the drawing. The photosensitive drum 51 rotates at low speed in the direction of the arrow in the figure, and recording paper (not shown) advances from the photosensitive drum 51 toward the photosensitive drum 54. Further, 71 to 74 are beam detectors which output signals for aligning main scanning start positions iMt'Fc with respect to the photosensitive drums 51 to 54.

Reference numeral 61 denotes an fθ lens, which corrects focal fluctuations caused by the difference in the optical path length of the deflected laser beam between the central portion and both ends of the photosensitive drum 51, and corrects the difference in focus variation between the center and both ends of the photosensitive drum 51. 6. The optical system for the second photosensitive drum 52 is configured so that the optimum focus can be obtained at the same position as described above. The laser light 32 passes through the 12 laser beams and becomes parallel, which is scanned by the same rotating polygon mirror 22 as described above, passes through the fθ lens 62, is reflected by the reflecting mirror 42, and is guided to the photosensitive drum 52.

In this case, the distance between the collimator lenses 11 and 12 is such that the laser beams 31 and 32 are irradiated onto different surfaces of the rotating polygon mirror 22, as shown in the figure. For example, the first
The rotating polygon mirror 22 shown in the figure is an octahedron, in which case it is usually installed so that every other face is irradiated, and in the case of a tetrahedron, the adjacent faces are irradiated. It's normal.

However, the present invention is not necessarily applied only to the above halves, and it goes without saying that each laser beam may be applied to each different surface independently.

The photosensitive drums 51 and 52 are also connected to the photosensitive drums 53 and 54.
5. These optical systems are the same as those for the photosensitive drums 51 and 52, so redundant explanations will be avoided, and corresponding configurations will be referred to with dashes. Add a number.

FIG. 1 fully describes the case where there are four photosensitive drums. In this case, for example, the photosensitive drum 51 is for cyan, the photosensitive drum 52 is for magenta, the photosensitive drum 53 is for yellow, and the photosensitive drum 54 is for black. It's a drum, and it's equipped with four lasers, each with its own laser. These four color image signals drive each of the four lasers through a drive circuit.

Furthermore, as understood from the figure, the photosensitive drums 51 and 52
,' Since the scanning directions of 53 and 54 are reversed, the output order of the color image signals for each line is reversed for the photosensitive drums 52 and 54 via the drowsiness memory for several 2 inches of Eline. The color image signal is inputted to the one-zero drive circuit.

FIG. 2 is a block diagram illustrating the entire configuration of an electrical memory for reversing the output order and reading out data. In the block diagram, one line of serial data in the positive direction is transferred to LIFO (L
AST IN FIR8TOUT) Buffer memory 1
Stored in 00. At the time of output, the direction is opposite to that at the time of input, that is, L
Output to AST INFIR8T OUT. Therefore, one line of image information on the output line 102 is reversed.

Sorial data for one line in the positive direction (INDATA
) is output to the LIFO memory 100 in reverse order, which will be explained in more detail with reference to FIGS. 3 and 4.

Here, it is assumed that the LIFO buffer memory 100 has a data storage area for the mazemme data ef line. The reference vibration from the crystal oscillator 107 is passed through the frequency divider 106! l) The frequency is divided by 1/N to create a predetermined pixel clock. This pixel clock is the R/W controller 1
04) Time-sharing, READ C0UNTEIe1
It is distributed to 03A and WRITE C0UNTER103B.

The timing of this time-division division of the pixel clock is as shown in FIG. 4, in which the horizontal synchronization signal BD is received and the READ clock is first generated.

((C) in Fig. 4) The horizontal synchronizing signal BD is a signal for aligning the start positions of the main scan with respect to the photosensitive drum 52. This is generated by detecting the laser beam by the beam detector 72 as the beam passes through.

Next, a WRITE clock is similarly applied within the blanking period of the image. (03 in the same figure)) The allocated clock is the counter 103A.

LIF is until the predetermined count number is reached by 103B.
It is transmitted to O memory and stops when a predetermined count is reached. This prevents overflow. As described above, data in the forward direction is input to the LIFO memo IJ 100 on the input line 101.
WRITECLO%K108A. (0 in Figure 4) WRITE CL when the predetermined number (i.e., the number equivalent to one line data) is reached.
OCK stops and stops inputting data. Thus LI
FO memo! The data stored in J100 is read from the READ CLO starting from the horizontal synchronization signal plane ((5) in Figure 4).
The data is retrieved in reverse order in synchronization with CK (C in Figure 4). This is also READ by taking out a predetermined number of sheets.
Stop CLOCK.

In the manner described above, the order of image data is reversed. This reversed image data is output to the laser driver 101, which drives the laser driver 101 for the photosensitive/photosensitive drum 52 according to this data, and causes the laser element 102 in the laser unit to print magenta on the photosensitive drum 52. image formation is performed.

In addition, the cyan memory 20 does not require reversing the output order.
0 is FIFO (FIR8T IN FIR8TOUT
) using buffer memory. The FIFO buffer memory 200 also has the same 4 values as the LIFO buffer memory 100.
)), WRITE clock WC and READ clock R
When C inputs J, the image for cyan is stored in the FIFO buffer memory within the blanking period in synchronization with the WRITE clock WC. Read from buffer memory 200.

Then, according to this image data, the laser driver 201
is driven, and the laser If in the laser unit, child 20
2, a cyan image is formed on the photosensitive drum 51. Note that similar circuits are also provided for the photosensitive drums 53 and 54.

Further, it is preferable that image information is stored in the memory 100 during a non-recording time (blanking period). If the non-recording time is short and the memory transfer time cannot be obtained, use the memo! method as shown in Figure 5. 7100.100ThUsing a tuple buffer method with two (two or more is possible), data is stored in the other memory at the time of reading from one memory.
V
A soft register is added to the laser drive circuit to correct color shift for C reverse and four colors as necessary.

The dimensions of the embodiment shown in FIG. be. Also, the distance between the photosensitive drums 51 and 41: 190, and the reflecting mirror 41
Distance between and fθ lens 61: 30. The rotation axis of the focal length rotation of the fθ lens 61 is located at the center of the distance between the photosensitive drums 51 and 52 in the length direction.

FIG. 6 is a perspective view illustrating a second embodiment of the present invention. The difference between the configuration shown in the second embodiment and the configuration shown in the first embodiment is that the scanner can be integrated and the polygon mirror driving motor (not shown) can be integrated into one.

Semiconductor laser confectionery (not shown) and collimator lens 1
Consisting of 5, 16, 17, 18/-za unit) 20
The emitted collimated beam is reflected and deflected by two-stage rotating polygon mirrors 23 and 24, respectively.
The light enters the aforementioned fθ lens 65.66.67.68, is reflected by the reflection mirror 45.46.47.48, and then forms an image on the photosensitive drum 55.56.57.58.

That is, four lasers are fixed in the laser unit 20, arranged on the back side ψ糺23.24μI71Ykl, and 1F/)Moke7'A-i! : Let's rotate.

Here, the rotation center positions of the rotating polygon mirrors 23 and 24 are located at the center of the photosensitive drums 56 and 57, and the optical path lengths of the photosensitive drums 55 and 58 are different from the optical path lengths of the photosensitive drums 56 and 57. Therefore, the focal length of the fθ lens 65 and 6
8 has the same focal length, and 66 and 67 have the same focal length, but the focal lengths of 65 and 68 are also longer than those of 66 and 67. Since the focal lengths (optical path lengths) of the fθ lenses 65 and 68 and 66 and 67 are different, the scanning speeds of the lasers on the photosensitive drums 55 and 58 and the photosensitive drums 56 and 57 are different. In order to correct this, the electrical processing shown in FIG. 7 is performed on the image signal input to the laser driver.

Next, referring to FIG. 7, we will explain the modulation method for deflection systems with different optical path lengths. I will clarify.

When the focal length of the fθ lenses 65 and 68 is fI, and the focal length of the fθ lenses 66 and 67 is f, the image signal time of one line to the photosensitive drums 55 and 58 is tI, and the image signal time to the photosensitive drums 56 and 57 is Let the signal time be t. In this case, t+ / t2 = ft / fI, and if the clock frequency of one pulse of the image signal is w for the photosensitive drums 55 and 58, and W2 for the photosensitive drums 56 and 57, Wl/W2=f2/f. The input signal of the laser modulator is corrected so as to maintain the relationship of .

FIG. 8 shows means for generating these two pixel clocks. Oscillator 110A.

110B is composed of a crystal oscillator etc. that provides the above-mentioned relationship ws/%=ft/fI. This output is divided into 1 by 1/N frequency dividers 111A and IIIB.
/N. Even after this, w,' / w2 =
-6 relation 1 is satisfied.

A pixel clock is generated in the manner described above.

The outputs of the oscillator 110A and the frequency divider 111A are used as synchronization number 93 for the photosensitive drum 55,58, and the oscillator 110B
, the output of the branching unit 111B may be configured to be used as a synchronizing signal for the photosensitive drums 56 and 57 to control writing of data to the memory and reading of data from the memory. Also, regarding the memory, the memory for the photosensitive drums 55 and 56 is F.
Memo for photosensitive drum 57°58 in IFO buffer memory! It may be configured with a JtLIFO buffer memory.

Due to the above correction, the dot densities on each photosensitive drum can be made equal even if the laser beam scanning speed on the photosensitive drums is different because the optical path lengths are different.

The actual dimensions in Example 2 are described below.

The unit is the key.

IMJ m of collimator lenses 16 and 15: 50, distance between rotating polygon @24 and 23: 50, fσ lens small 65 and 6
The focal lengths of 8, 66 and 67 are 300 and 220 respectively.
, distance between photosensitive drum 55 and reflecting mirror 45: 140. Distance between photosensitive drum 56 and reflecting mirror 46: 190, reflecting mirror 45
Distance between and fθ lens 65: 160, reflector 46 and fθ
Distance to lens 66: 30. The rest is the same as in Example 1.

Above we have described the case where the fθ lenses have different focal lengths, but
If some consideration is given to the y-quantitative arrangement, it is possible to perform actual observation with the same focal point 1+1i apart. In this case, the distance between the two rotating polygon mirrors may be approximately the same as the distance between the drums. Therefore, it is preferable to arrange the rotating polygon mirrors on the shafts on both sides, with the drive motor for the rotating polygon mirror in between. With such an arrangement, the electrical treatment described above becomes unnecessary.

Incidentally, in the above embodiment, two polygon mirrors are arranged on the same jtJt, but it is also possible to form a polygon with one polygon mirror.

The above description has been made based on the embodiments, but they are suitable for the present invention.

Furthermore, the lasers corresponding to the image signals may be arranged in a hybrid manner, and in the case of semiconductor lasers, array lasers can also be used. The laser light may be guided to a plurality of drums at once, or the laser light may be separated by a beam splitter or the like, modulated with different image signals, and then guided to a plurality of drums.

Further, the scope of application of the present invention is not limited to color printers, but can also be applied to, for example, when image signals are superimposed on a single color printer.

As described above, according to the present invention, the first laser beam beam (
The order in which the image signals are read out for the second laser beam is reversed, and the scanning directions of the first laser beam and the second laser beam are opposite to each other. It is possible to record images on the recording site, shortening the recording time and simplifying the configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a first embodiment of the present invention;
FIG. 2 is a block diagram showing the LIFO memory, and FIG. 3 is a block diagram showing the configuration of the memory read control.
4 is a timing chart of each part in the block diagram shown in FIG. 3, FIG. 5 is a block diagram showing the double buffer method, and FIG. 6 is an example of an actual car pile of ', -1'r 2 of the present invention. A perspective view showing the I'i'7 configuration, FIG. 7 is a timing chart for explaining the modulation method for polarizing fibers with different optical path lengths, and FIG. FIG. In the figure, 10.20 is the laser beam]・, 11°12.1
5, 16, 17.18 are collimator lenses, 22, 23
．． 24 is a rotating polygon mirror, 51 to 58 are photosensitive drums, 61,
62. 65-68 are fθ lenses, 100L/yo LIFO
Buffer memory, 103A and B are counters, 104 is R
/W controller, 106 is a frequency divider, 107 is an oscillator,
200i, J: FIFO buffer memory. Applicant Canon Sakiki Co., Ltd. 84 products 5M 00

Claims (1)

Scope of Claims: (1) a first laser beam generating means driven in accordance with first image information; a second laser beam generating means driven in accordance with second image information; a first recording body that is scanned by a first laser beam outputted from the first laser beam generation means to form a first image; a second recording body that is scanned by a second laser beam in a direction opposite to the scanning direction of the first laser beam to form a second image; a first image information output means that outputs the second image information to the first laser beam generation means; and a second image information output that outputs the second image information to the second laser beam generation means in the reverse order of inputting the second image information. A recording device having means. (2. In Claim 1, the recording device is characterized in that the first image information output means has a FIFO buffer memory. (3) In Claim 1, the recording device characterized in that the first image information output means has a FIFO buffer memory. A recording device characterized in that the image information output means has a LIFO buffer memory. (4) In claim 1, furthermore, the first laser beam and the second laser beam are used for the first recording. 1. A recording apparatus comprising: a deflection means for deflecting the laser beam toward the body and a second recording body, the deflection means being used in common for the first laser beam and the second laser beam.