JP2004098472A - Image formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image formation apparatus which can elongate a life of a laser by a smaller controlling load. <P>SOLUTION: The image formation apparatus has a light detecting means, a synchronous detection signal generating means, and an image data control circuit. The light detecting means carries out main scanning control by illuminating an image formation face with two or more precedently/succeedingly scanning laser lights by repetitively deflecting the lights by a constant angle, detects the laser light reaching inside a deflection range and outside an image write region by this control, and generates an analog signal. The synchronous detection signal generating means controls a timing for generating each write position signal on the basis of the analog signal of a plurality of pulses outputted from the light detecting means. The precedent laser light and the succeeding laser light are controlled to be turned on/off within the image write region by an on/off control means for detecting the synchronous detection signal, and a control circuit independent of the image data control circuit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly, to a digital color image forming apparatus such as a color laser printer, a color digital copying machine, and a digital multifunction peripheral thereof.
[0002]
[Prior art]
A general digital color image forming apparatus includes, in addition to a photosensitive drum, a pre-exposure apparatus including an LED array, a primary charger having a grid, an image exposure apparatus using a laser as a light emitting element, and a surface potential of the photosensitive drum. It comprises a surface voltmeter for detection, a developing device, a transfer charger, a separation charger, a cleaning device (not shown), and the like. Since the operation of the digital color image forming apparatus is well known, a description thereof will be omitted.
[0003]
By the way, as shown in FIG. 7, in a light beam writing scanning optical system conventionally used in an LBP (laser beam printer) or the like, a laser diode 6 and a polygon mirror 1 for scanning light from the laser diode 6 are used. A scanning lens 2, a bending mirror 5 for bending light reflected from the polygon mirror 1 obtained through the scanning lens 2, a BD mirror 3 provided at a predetermined position in a region immediately before a writing position by a light beam, and a BD mirror A BD sensor 4 for detecting the reflected light from 3 is mounted inside the optical box 7.
[0004]
In this case, the laser beam from the laser diode 6 is emitted toward the polygon mirror 1 and scanned by the polygon mirror 1. The scanned laser beam is guided to the bending mirror 5 by the scanning lens 2 and is bent by the bending mirror 5.
[0005]
Synchronous detection is performed so that the laser beam can be written from a specified position on the photoconductor for each line. That is, the reflected laser beam from the BD mirror 3 is detected by the BD sensor 4, and the write start position is temporally defined by the detection signal.
[0006]
FIG. 8 shows the relationship between the laser light power and the scanning time of the BD detection signal output.
In FIG. 8, the time for turning on the laser diode 6 for detection is t1, and the time for turning on the laser diode 6 in the entire write effective area is t0. The pulse width of the detection signal obtained as a result of receiving the detection light by the BD sensor 4 is t3. As described above, t1 is a value including a scanning speed error margin of the laser beam to some extent so that the BD sensor 4 reliably performs the synchronization detecting operation.
[0007]
However, in such a conventional example, the time for turning on the laser diode 6 as detection light at the time of synchronization detection is relatively longer than the time for turning on the laser diode 6 for actually performing optical writing. In consideration of the ON lifetimes of these products, they are non-negligible values, and are a major bottleneck in extending the lifetime in product design.
[0008]
Therefore, in order to solve the above-described problems, the conventional image forming apparatus uses a laser light power in a synchronization detection period for detecting write synchronization in a laser light scanning period for a predetermined time from the synchronization detection period. An attempt is made to extend the life of the laser by reducing the laser light power in the effective scanning period after the passage by a predetermined amount (for example, see Patent Document 1).
[0009]
That is, in this image forming apparatus, the laser beam power in the synchronization detection period for detecting write synchronization in the scanning period by the scanning unit is determined by the laser beam power in the effective scanning period after a predetermined time has elapsed from the synchronization detection period. It is characterized by comprising control means for reducing the amount by a fixed amount.
[0010]
[Patent Document 1]
JP-A-6-51219
[Problems to be solved by the invention]
However, in this apparatus, the mechanism for switching the control of the laser beam power between the synchronization detection period and the other period is required, and the control period is performed for each line of the main scanning. Since it is indispensable, the control load of the image forming apparatus increases.
[0012]
Therefore, an object of the present invention is to solve the above-mentioned problems and disadvantages and to extend the life of the laser. That is, an object of the present invention is to provide an image forming apparatus capable of extending the life of a laser with a smaller control load.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, an image forming apparatus is an image forming apparatus that forms a color image by repeatedly charging, exposing, and developing a photoreceptor. Means for performing main scanning control by irradiating the image forming surface by repetitively deflecting two or more laser beams scanned in the preceding / following directions by a predetermined angle, and within a deflection range and image writing area by the main scanning control. Photodetection means for detecting an externally reaching laser beam to generate an analog signal, and synchronous detection for controlling the timing of generating each writing position signal based on a plurality of pulse analog signals output by the photodetection means It has a signal generating means and an image data control circuit.
[0014]
According to the second aspect of the present invention, the image forming apparatus further includes a control circuit independent of an image data control circuit for controlling turning on / off of a preceding laser beam and a following laser beam in the image writing area. 2. The image forming apparatus according to claim 1, wherein
[0015]
According to the third aspect of the present invention, in the image forming apparatus, the on / off control means for detecting the synchronization detection signal and the control circuit independent of the image data control circuit are provided in the image writing area with the preceding laser light. 3. The image forming apparatus according to claim 2, wherein the image forming apparatus controls turning on / off of the laser beam and a subsequent laser beam.
[0016]
According to the fourth aspect of the present invention, the image forming apparatus further includes means for supplying data corresponding to a white image to the image data control circuit when each laser beam is turned off in the image writing area. Or the image forming apparatus according to 3.
[0017]
According to the fifth aspect of the present invention, the image forming apparatus controls the writing linear velocity when any one of the preceding laser light and the following laser light is turned off in the image writing area. The image forming apparatus according to any one of claims 1 to 4, further comprising means for interlocking functions.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0019]
The present invention is an image forming apparatus that forms a color image by repeatedly charging, exposing, and developing a photoreceptor, and includes at least two laser beams having a mechanical configuration that scans ahead and behind. The main scanning control is performed by irradiating the image forming surface with repetitive deflection at a constant angle, and a laser beam that reaches within the deflection range by the laser beam scanning control and outside the image writing area is detected to generate an analog signal. An image data control circuit for controlling the timing of generating each write start position signal based on a plurality of pulse analog signals output by the light detection means; and an image data control circuit. It relates to a forming apparatus.
Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.
[0020]
First, the operation of an embodiment of the image forming apparatus according to the present invention will be systematically described with reference to FIG.
FIG. 1 is a schematic block diagram of a control system of a color printer used as an example of an image forming apparatus according to the present embodiment. The description will be made sequentially based on this.
[0021]
This block diagram includes a host machine 101, a controller 102, a key input unit (operation panel) 103, a main control unit 104, a memory unit 105, a printer drive control unit 106, and a printer unit 107. .
[0022]
The printer drive control unit 106 controls driving of each unit of the printer unit 107. The controller 102 controls image data from the host machine 101. The memory unit 105 stores the image data transferred to the controller 102. A key input unit (operation panel) 103 includes various keys for setting the number of prints, paper size, enlargement / reduction, other settings, clearing a setting mode, and starting / stopping operation. The main control unit 104 controls each unit according to a signal from the key input unit 103, outputs a command signal to the printer drive control unit 106, and starts a printing operation.
[0023]
The present invention relates to the printer drive control unit 106, the printer unit 107, and the main control unit 104 that controls the system.
[0024]
First, the main controller 104 transfers the image data from the controller 102 to the printer drive controller 106. The printer drive control unit 106 has a function of driving the printer unit 107 based on the transferred image data and printing the image data.
Printing is performed by repeating this operation in the main scanning and sub-scanning directions by the printer drive control unit 106 (the writing unit 200 in FIG. 2).
[0025]
Next, the operation inside the printer unit 107 in FIG. 1 will be briefly described with reference to FIG.
[0026]
A latent image is formed on the photoreceptor belt 201 by laser light exposed from the writing unit 200 (same as the printer drive control unit 106 in FIG. 1), and toner development is performed by the developing units 202 for each of Magenta, Cyan, Yellow, and Black. Perform Further, the photosensitive member is removed / charged by the charging brush 203, the charge removing (brush) 204, and the photosensitive member cleaning 205.
[0027]
Thereafter, the intermediate transfer is performed by the intermediate transfer belt 206, the cleaning brush roller 207, and the primary transfer brush 208, and the paper fed from the paper feed tray 209 is conveyed by the secondary transfer roller 210 to form an image.
[0028]
The formed image is thermally fixed by the fixing unit 211, passes through the branching unit 212, and is discharged to the main body, or in the case of FIG.
[0029]
Through a series of operations described above, printing is performed based on print data input from the host machine 101 via the controller 102.
[0030]
Hereinafter, main operations of an embodiment of the image forming apparatus according to the present invention will be described.
[0031]
In the image forming apparatus having the above-described configuration, the present embodiment relates to the writing unit 200 in FIG. 2 and the main control unit 104 and the writing control unit (printer driving control unit 106) illustrated in FIG. Against.
In connection with them, the 2LD method will be further described.
[0032]
First, a first example, which is an embodiment of the image forming apparatus according to the present invention, will be described.
[0033]
The first embodiment is an image forming apparatus that forms a color image by repeatedly charging, exposing, and developing a photoreceptor, and includes at least two laser beams having a mechanical configuration that scans ahead and behind. The main scanning control is performed by irradiating the image forming surface by repeatedly deflecting the laser beam by a constant angle, and the laser beam that reaches within the deflection range by the laser beam scanning control and outside the image writing area is detected to generate an analog signal. A photodetector, a synchronous detection signal generator for controlling a timing of generating each write start position signal based on a plurality of pulse analog signals output from the photodetector, and an image data control circuit. In the image forming apparatus, a preceding laser beam (hereinafter referred to as LD1 or preceding LD) and a succeeding laser beam (hereinafter referred to as LD2 or following L) D) is turned on / off in an image writing area by a lighting / light-off control for detecting the synchronization detection signal and a control circuit independent of the image data control circuit. The aim is to make it possible to form an image even when the preceding LD is turned off and only the preceding LD is turned on, and to make the power control of each LD constant regardless of the image area.
[0034]
The first embodiment will be described in more detail with reference to the circuit configuration diagram shown in FIG. 3 and the timing diagrams shown in FIGS.
[0035]
Turning on / off of LD1 and LD2 is performed by setting from register 301 (FIG. 3) of the LD control circuit in the write control unit attached to write unit 200 in FIG.
[0036]
Here, the lighting control timings of the LD1 and LD2 for normal synchronization detection are as shown in FIG.
[0037]
First, the preceding LD, that is, LD1, is turned on outside the image writing area from a position that matches the preset register setting value and the main scanning counter value, and a synchronization detection pulse signal is obtained from a synchronization detection signal generating means (not shown). . This corresponds to the comparison circuit 304 → OR circuit 305 → AND circuit 308 in FIG.
[0038]
Thereafter, the subsequent LD, that is, LD2, is turned on from the position where the other register setting value and the main scanning counter value match, and a second synchronization detection signal pulse is obtained. This corresponds to the comparison circuit 306 → OR circuit 307 → AND circuit 309 in FIG.
[0039]
The writing start position of the main scanning is controlled by these two synchronization detection signal pulses. In this control, a register flag (LDDT_OFFALL) for turning off both data of LD1 and LD2 regardless of whether the data is inside or outside the image writing area is prepared. The data is turned off in all periods.
[0040]
On the other hand, for these register flags (LDDT_OFFALL), register flags (LDDT1OFF, LDDT2OFF) for turning off each LD only in the image writing area are prepared.
[0041]
By taking the logic of these register flags, the LDDT_OFFALL flag is turned off ("L") and the LDDT1OFF is turned on ("H"), thereby turning off the LD1 only in the writing image area and turning off the LDDT_OFFALL flag. "L") and turning on LDDT2OFF ("H") gives control to turn off LD2 only in the written image area (see NOR circuits 302 and 303 in FIG. 3).
[0042]
As a result, the lighting function outside the writing image area necessary for lighting for synchronization detection remains as it is, and only the writing image data is turned off. Therefore, the LD data for synchronization detection is normally turned on, and the synchronization detection is performed. It is possible to avoid abnormal operations such as abnormalities. That is, although the 2 LD system is used, image formation can be performed by lighting only one of the LDs (see FIG. 5). Further, with the logic circuit configuration of FIG. 3, lighting / lighting out by other combinations is performed.
[0043]
Furthermore, since the LD inside and outside the writing image area is controlled by turning on or off, the LD can be realized with a simple circuit configuration without the control of the LD power.
[0044]
Next, a second example, which is an embodiment of the image forming apparatus according to the present invention, will be described with reference to FIG.
[0045]
In the second embodiment, in the image forming apparatus of the first embodiment, when each LD is turned off in the image writing area, the data corresponding to the white image is given to the image data control circuit to load the LD control circuit. The aim is to reduce.
[0046]
In the present embodiment, when each LD is turned off in the image writing area, data corresponding to a white image is given to the above-described image data control circuit, and each image data from the image data control circuit in the writing image area is provided. In contrast, a mechanism for providing white image data to LD1 data corresponding to LDDT1OFF or LD2 data corresponding to LDDT2OFF is provided.
[0047]
Thus, even if the LDDT_OFFALL flag is set to OFF without using the register flags (LDDT1OFF, LDDT2OFF) of the second embodiment, the same control becomes possible. Can be reduced (see FIG. 6).
[0048]
Next, a description will be given of a third embodiment as an embodiment of the image forming apparatus according to the present invention.
[0049]
The third embodiment is different from the image forming apparatus of the first embodiment in that, when one of the LDs LD1 and LD2 is turned off in the image writing area, the function of controlling the writing linear velocity is linked. By halving the speed and doubling the resolution in a simulated manner, it is intended to obtain an image equivalent to that obtained when two LDs are turned on even when one of the LDs is turned on.
[0050]
In this embodiment, when either LD 1 or LD 2 is turned off in the image writing area, the function of controlling the writing linear velocity is linked, for example, when the LDDT 2 OFF flag is turned on and the LD 2 is turned off Although the printing is performed only by the LD1, the image at this time is an image in which the LD1 is printed every two lines.
[0051]
Therefore, the resolution in the sub-scanning direction is doubled by reducing the writing linear speed to half speed. In other words, an image that was originally 600 dpi at 2LD becomes equivalent to 300dpi by printing only LD1, so this is 1200 dpi (equivalent to 600 at 1LD).
[0052]
By adopting such a configuration, even if one of the LDs is turned off, an image of the same quality as that of the original 2LD can be secured even if one of the LDs is turned off, unless the magnification is considered as a problem.
[0053]
Although the above embodiment uses the color printer of FIGS. 1 and 2, any image forming apparatus having the same functions as those shown in the first to third embodiments may be used. The type does not matter.
That is, the present invention is not limited to a color printer, but is widely applied to other image forming apparatuses such as a color copying machine, a color facsimile, and a multifunction peripheral thereof.
[0054]
【The invention's effect】
According to the first to fifth aspects of the present invention, there is provided an image forming apparatus for forming a color image by repeatedly charging, exposing, and developing a photoreceptor. The main scanning control is performed by irradiating the image forming surface by repeatedly deflecting at least two laser lights having a constant angle, and the laser light that reaches within the deflection range by the laser light scanning control and outside the image writing area is controlled. One light detecting means for detecting and generating an analog signal, and a synchronous detecting signal generating means for controlling a timing for generating each writing start position signal based on a plurality of pulses of the analog signal output by the light detecting means. In the image forming apparatus including an image data control circuit, the LD1 and the LD2 are turned on / off for detecting the synchronization detection signal. By controlling the lighting / extinguishing in the image writing area by a control circuit independent of the image data control circuit, the succeeding LD is extinguished and an image can be formed even when only the preceding LD is turned on. In addition, the power control of each LD can be kept constant regardless of the image area.
[0055]
According to the fourth and fifth aspects of the present invention, in the image forming apparatus according to the first to third aspects, when each LD is turned off in the image writing area, data corresponding to a white image is supplied to the image data control circuit. This reduces the load on the LD control circuit.
[0056]
According to the fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, when one of the LD1 and LD2 is turned off in the image writing area, the function of controlling the writing linear velocity is linked. By setting the writing linear speed to half speed and doubling the resolution in a pseudo manner, it is possible to obtain an image equivalent to that when two LDs are turned on even when one of the LDs is turned on.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a control system in an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a configuration diagram of a color printer as an embodiment of the image forming apparatus according to the present invention.
FIG. 3 is a circuit configuration diagram of an LD control circuit in an embodiment of the image forming apparatus according to the present invention.
FIG. 4 is a timing chart of the on / off control of the LD1 and LD2 of the 2LD system.
FIG. 5 is a timing chart of turning on / off of LD1 and LD2 in an embodiment of the image output apparatus according to the present invention.
FIG. 6 is a timing chart for controlling turning on / off of LD1 and LD2 in another embodiment of the image output apparatus according to the present invention.
FIG. 7 is a perspective view of a light beam writing / scanning optical system used for a conventional LBP or the like.
FIG. 8 is a diagram showing the relationship between laser light power and BD detection signal output in a conventional LBP or the like with respect to scanning time.
[Explanation of symbols]
6 Laser diode 104 Main control unit 106 Printer drive control unit 107 Printer unit 200 Writing unit 301 Register 302, 303 NOR circuit 304, 306 Comparison circuit 305, 307 OR circuit 308, 309 AND circuit

Claims (5)

An image forming apparatus that forms a color image by repeatedly performing charging, exposure, and development on a photoconductor,
The image forming apparatus includes:
Means for performing main scanning control by irradiating an image forming surface by repeatedly deflecting two or more laser beams scanned in the preceding / following directions by a constant angle;
Light detection means for detecting a laser beam that reaches the deflection range and outside the image writing area by the main scanning control and generates an analog signal,
Synchronization detection signal generation means for controlling the timing of generating each write start position signal based on a plurality of pulse analog signals output by the light detection means;
An image data control circuit;
An image forming apparatus comprising: 2. The image data control circuit according to claim 1, further comprising a control circuit independent of the image data control circuit for controlling turning on / off of the preceding laser light and the following laser light in the image writing area. Image forming device. Lighting / light-out control means for detecting the synchronization detection signal and a control circuit independent of the image data control circuit,
3. The image forming apparatus according to claim 2, wherein turning on / off of the preceding laser light and the succeeding laser light is controlled in the image writing area. At the time of turning off each of the laser lights in the image writing area,
4. The image forming apparatus according to claim 1, further comprising: a unit that supplies data corresponding to a white image to the image data control circuit. When the laser light of the preceding laser light and the laser light of the succeeding laser light in the image writing area is turned off, further comprising means for interlocking a function of controlling a writing linear velocity. The image forming apparatus according to claim 1, wherein:

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