JP6993849B2 - Emission intensity reference signal generation device, image forming device, multifunction device and emission intensity reference signal generation method - Google Patents

Description

The present invention relates to a light emission intensity reference signal generation device, an image forming device, a composite machine, and a light emission intensity reference signal generation method for generating a light emission intensity reference signal that specifies the light emission intensity of a laser light source, and in particular, droop correction and shading correction. The present invention relates to a light emission intensity reference signal generation device, an image forming device, a composite machine, and a light emission intensity reference signal generation method for generating a light emission intensity reference signal tuned for.

The droop phenomenon may be a problem in an electrophotographic image forming apparatus using a laser. The droop phenomenon is a phenomenon in which images having different densities are formed for image signals of the same level due to fluctuations in the amount of heat generated by the laser and the amount of charge in the photoconductor. Even if a desired image density is obtained by APC (automatic power control) at the initial stage of each main scan, the density of the formed image varies with respect to the image signal of the same level as the main scan progresses.

Taking the droop phenomenon due to heat generation during laser emission as an example, the closer the image is from white to black, the stronger the laser emission intensity and the larger the amount of heat generated, the lower the luminous efficiency and the more prominent the droop phenomenon. .. Therefore, for the same gray level image signal, the luminous efficiency of the laser is lowered and the droop phenomenon becomes more remarkable when it continues from the black level image signal than when it continues from the white level image signal. For example, as shown in FIG. 1, the emission intensity corresponding to the same gray level image signal is lower at the position P2 in the sub-scanning direction than at the position P1 in the sub-scanning direction, so that the level of the formed image is lower. It will go up. That is, the gray 901 corresponding to the position P2 in the sub-scanning direction is brighter than the gray 903 corresponding to the position P1 in the sub-scanning direction.

Japanese Unexamined Patent Publication No. 2013-129133 Same inventor Japanese Unexamined Patent Publication No. 9-314908 Japanese Patent Application Laid-Open No. 2002-86793 Japanese Unexamined Patent Publication No. 11-291547 Japanese Patent Application Laid-Open No. 2003-87508 Japanese Unexamined Patent Publication No. 2008-284854

In Patent Document 1, a correction value of a control voltage according to external factors such as image information and ambient temperature (that is, a correction value for correcting the droop characteristic) is read from a table, and the control voltage corrected by this correction value is read. Disclosed is an invention that outputs a re-corrected control voltage obtained by multiplying a shading pattern correction value obtained by referring to another table to a laser driver.

However, in the invention of Patent Document 1, since it is necessary to prepare a table for correcting the droop characteristic in addition to the table for correcting shading, a large amount of memory capacity is required and the cost is increased. Was. In addition, when the image data had multiple values, the density could not be corrected correctly.

Patent Document 2 discloses an invention in which pixel data is droop-corrected by correcting it with a correction signal generated based on the immediately preceding n pixel data and the time between pixels.

However, in Patent Document 2, since the configuration is such that a table is referred to, a large amount of memory capacity is required and the cost is increased. In addition, shading correction could not be performed at the same time as the light amount correction.

Patent Document 3 discloses an invention that corrects droop by adjusting the current for driving each laser light source based on the image data of all the plurality of laser light sources corresponding to the plurality of lines.

However, in Patent Document 3, since the configuration is such that a table is referred to, a large amount of memory capacity is required and the cost is increased. In addition, when the image data had multiple values, the density could not be corrected correctly. Further, the shading correction could not be performed at the same time as the light amount correction.

In Patent Document 4, the droop is corrected by driving the laser light source with a current obtained by combining a constant current in one scanning period and a current controlled according to the on-time of the laser light source in one scanning period. The invention to be used is disclosed.

However, in Patent Document 4, since the configuration is such that a table is referred to, a large amount of memory capacity is required and the cost is increased. In addition, when the image data had multiple values, the density could not be corrected correctly. Further, the shading correction could not be performed at the same time as the light amount correction.

Patent Document 5 discloses an invention in which if continuous lighting is detected, the droop is corrected by adjusting the drive current of the laser light source based on the data obtained by referring to the table.

However, in Patent Document 5, since the configuration is such that a table is referred to, a large amount of memory capacity is required and the cost is increased. In addition, when the image data had multiple values, the density could not be corrected correctly.

Patent Document 6 discloses an invention in which the droop is corrected by correcting the exposure energy according to the degree of influence of the previously exposed exposed pixels in the same line.

However, in Patent Document 6, shading correction could not be performed at the same time as the light amount correction.

Therefore, the present invention provides an emission intensity reference signal generator, an image forming apparatus, a multifunction device, and an emission intensity reference signal generation method that generate an emission intensity reference signal that corrects both droop and shading with a simple configuration. The purpose is.

According to the present invention
A droop correction signal generation means that generates a droop correction signal whose amplitude fluctuates based on an image signal,
An amplitude modulation means that modulates the amplitude of the shading correction signal with the amplitude of the droop correction signal, and
An emission intensity reference signal generation means that generates an emission intensity reference signal based on a shading correction signal whose amplitude is modulated by the amplitude modulation means.
The emission intensity reference signal generation apparatus is provided.

Further, according to the present invention, there is provided an image forming apparatus including the above-mentioned emission intensity reference signal generation apparatus.

Further, according to the present invention, there is provided a multifunction device including the above-mentioned emission intensity reference signal generation device.

Further, according to the present invention, there is a droop correction signal generation step of generating a droop correction signal whose amplitude fluctuates based on an image signal.
An amplitude modulation step that modulates the amplitude of the shading correction signal with the amplitude of the droop correction signal, and
The emission intensity reference signal generation step of generating an emission intensity reference signal based on the shading correction signal whose amplitude is modulated by the amplitude modulation means, and
A method for generating a emission intensity reference signal is provided.

Further, according to the present invention, a program for making a computer function as the above-mentioned document reading device is provided.

According to the present invention, both droop and shading can be corrected with a simple configuration.

It is a figure which shows the printing example of the test pattern image by the conventional example. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by 1st Embodiment of this invention. (A) shows the waveform of the droop correction signal generated when the image level is zero by the emission intensity reference signal generator according to the first embodiment of the present invention, and (b) is the first of this invention. The waveform of the droop correction signal generated when the image level is half of the maximum value by the emission intensity reference signal generator according to the embodiment of the above is shown, and (c) shows the emission intensity according to the first embodiment of the present invention. The waveform of the droop correction signal generated when the reference signal generator has the maximum image level is shown. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by the 2nd Embodiment of this invention. It is the first figure which shows the waveform of the signal generated in each part of the emission intensity reference signal generation apparatus by the 2nd Embodiment of this invention. FIG. 2 is a second diagram showing a waveform of a signal generated in each part of the emission intensity reference signal generation device according to the second embodiment of the present invention. (A) shows the waveform of the image signal input by the emission intensity reference signal generator according to the second embodiment of the present invention, and (b) is the emission intensity reference signal according to the second embodiment of the present invention. The emission intensity reference signal output when the generator inputs the image signal of (a) is shown in comparison with the emission intensity reference signal of the conventional example, and (c) is emission according to the second embodiment of the present invention. The waveforms of other image signals input by the intensity reference signal generator are shown, and (b) shows the case where the emission intensity reference signal generator according to the second embodiment of the present invention inputs the image signal of (c). The output emission intensity reference signal is shown while being compared with the emission intensity reference signal of the conventional example. It is a figure which shows the printing example of the test pattern image by embodiment of this invention. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by the 3rd Embodiment of this invention. It is a flowchart for demonstrating the operation of the main part of the emission intensity reference signal generation apparatus by the 3rd Embodiment of this invention. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by 4th Embodiment of this invention. It is a flowchart for demonstrating operation of the main part of the emission intensity reference signal generation apparatus by 4th Embodiment of this invention. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by 5th Embodiment of this invention. It is a flowchart for demonstrating operation of the main part of the emission intensity reference signal generation apparatus by 5th Embodiment of this invention. It is a circuit diagram which shows the structure of the emission intensity reference signal generation apparatus by the 6th Embodiment of this invention. It is a flowchart for demonstrating operation of the main part of the emission intensity reference signal generation apparatus by 6th Embodiment of this invention. It is a flowchart for demonstrating operation of the main part of the emission intensity reference signal generation apparatus by 7th Embodiment of this invention. It is a flowchart for demonstrating operation of the main part of the emission intensity reference signal generation apparatus by 8th Embodiment of this invention. It is a conceptual sectional view of the multifunction device according to the tenth embodiment of this invention. It is a functional block diagram of the multifunction device according to the tenth embodiment of this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 2 shows a circuit for driving the laser light source D1 according to the first embodiment. This circuit includes a emission intensity reference signal generation substrate 101 and a laser light source substrate 131 including a laser light source D1.

The emission intensity reference signal generation substrate 101 emits emission intensity based on the beam horizontal position data k indicating the position where the laser light source is irradiated in the main scanning direction on the photoconductor and the binary image signal representing the image to be formed. A reference signal is generated and output to the laser light source substrate 131. The optical drive system that generates the beam horizontal position data k and the image signal generation unit that generates the binary image signal are not shown.

The emission intensity reference signal generation board 101 includes a voltage dividing circuit 103, an integrating circuit 105, a switching circuit 107, a filter circuit 109, a shading correction signal generation unit 111, and a buffer 113.

The voltage dividing circuit 103 outputs a signal obtained by dividing a predetermined power supply voltage V1 by a voltage dividing ratio that changes depending on the value of the binary image signal, and is used for a power supply and a voltage dividing circuit that generate a predetermined power supply voltage V1. It includes resistors R1, R2, R3 and a switch SW1 for changing the voltage division ratio. If there is no integrating circuit 105, the output voltage of the voltage dividing circuit 103 is V1 × R1 / (R1 + R2 + R3) because the switch SW1 is turned off when the level of the binary image signal is LOW, and when it is HIGH, it becomes V1 × R1 / (R1 + R2 + R3). Since the switch SW1 is turned on, it becomes V1 × R1 / (R1 + R2). At the initial stage of each line, the switch SW1 is turned off to make the output correspond to the white level. Further, although not shown, a circuit for forcibly setting the voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105 to V1 × R1 / (R1 + R2 + R3) corresponding to the white level may be provided at the initial stage of each line. ..

The integrator circuit 105 time-integrates the output voltage of the voltage divider circuit 103, which changes according to the level of the binary image signal, and is, for example, a capacitor C1 connected in parallel with the resistor R1. When the level of the binary image signal is LOW, the voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105 is configured with the resistors R1, R2, R3 and the capacitor C1 so as to approach V1 × R1 / (R1 + R2 + R3). When it is HIGH, it changes with the resistors R1 and R2 and the capacitor C1 and other time constants determined by the circuit configuration so as to approach V1 × R1 / (R1 + R2). Therefore, the voltage of the common output terminal fluctuates between V1 × R1 / (R1 + R2 + R3) and V1 × R1 / (R1 + R2) depending on the level of the binary image signal.

The shading correction signal generation unit 111 generates a shading correction signal S (k) that changes according to the beam horizontal position data k. The shading referred to here is shading in the optical system until the laser beam emitted by the laser light source D1 reaches the photoconductor drum, but may include shading in the image forming process unit. Shading in the optical system depends on the position of the laser beam in the main scanning direction on the photoconductor. If the shading in the image forming process unit has a component depending on the position of the main scanning direction of the laser beam, it can be corrected together with the shading in the optical system.

The shading correction signal generation unit 111 includes a shading correction signal generation table 121 and a pulse density modulation circuit (PDM circuit) 123. In the shading correction signal generation table 121, the beam horizontal position data k or the number of the horizontal division based on the data k (for example, the division obtained by dividing the entire range of the horizontal position into 32) is input as an address. , The shading correction signal corresponding to that address is output as data. The pulse density modulation circuit 123 inputs a shading correction signal and modulates it by ΔΣ to perform pulse density modulation. Therefore, the output of the shading correction signal generation unit 111 is a pulse density modulation wave representing the shading correction value.

Although the amplitude characteristic after passing through the filter circuit 109 in the subsequent stage is slightly deteriorated, a pulse width modulation circuit may be used instead of the pulse density modulation circuit. In this case, the output of the shading correction signal generation unit 111 is a pulse width modulated wave representing the shading correction value.

The switching circuit 107 switches a signal representing the output voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105 by the pulse density modulated wave output from the shading correction signal generation unit 111.

Specifically, the switching circuit 107 has a buffer 125, an inverter 127, switches SW2, and SW3, and the switches SW2 and SW3 are connected in series between the output terminal of the buffer 125 and the ground, and these switches are connected. The point to be connected is the output terminal. Since there is an inverter 127 for inverting the pulse density modulated wave, the switches SW2 and SW3 are complementarily turned on or off according to the level of the pulse density modulated wave.

Therefore, from the output terminal of the switching circuit 107, the amplitude of the pulse density modulation wave representing the shading correction value is modulated by the amplitude of the signal obtained by time-integrating the two voltages that are switched according to the level of the binary image signal. A signal will be output.

The filter circuit 109 includes a resistor R4 and a capacitor C2 as an example, and smoothes the output of the switching circuit 107. The output of the filter circuit 109 is supplied to the laser light source substrate 131 as a emission intensity reference signal via the buffer 113.

In the laser light source substrate 131, the emission intensity reference signal is switched by the switch SW4 based on the binary image signal, thereby driving the laser light source D1.

Therefore, the laser light source D1 emits a laser beam with an emission intensity based on the emission intensity reference signal adjusted so as to perform shading correction and droop correction on the emission intensity reference signal generation substrate 101 during the period when the switch SW4 is turned on. It will be emitted.

The shading correction and the droop correction are corrections for the emission intensity of the laser light source D1 in each main scan. That is, it is a correction for preventing the density of the formed image from fluctuating with respect to the original image of the same level in the same line. If the emission intensity at the initial stage of each main scan is determined by other control, shading correction and droop correction will be performed based on the determination, and a detailed description of that portion will be described later.

The lower waveforms of FIGS. 3A, 3B, and 3C are the voltage waveforms of the common output terminals of the voltage dividing circuit 103 and the integrating circuit 105. FIG. 3A shows a case where the binary image signal is always LOW. FIG. 3B shows a case where the binary image signal repeats HIGH and LOW with a duty of 50%. FIG. 3C shows a case where the binary image signal is always HIGH. By comparing these figures, it can be seen that the amount of change in the voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105 changes according to the average level of the binary image signal.

[Second Embodiment]
In the first embodiment, the image signal was a binary image signal. On the other hand, in the second embodiment, the image signal is a multi-valued image signal. In order to cope with this, in the second embodiment, as shown in FIG. 4, a PWM circuit 133 is added.

The PWM circuit 133 converts the multi-valued image signal into an image PWM signal. The image PWM signal is used to control the on / off of the switch SW4 on the laser light source substrate 131.

The image PWM signal is also used to control the on / off of the switch SW1 in the voltage dividing circuit 103 of the emission intensity reference signal generation board 101.

The configuration and operation of the other parts are the same as those of the first embodiment.

Therefore, in the second embodiment, even when a multi-valued image signal is input, the droop correction is performed according to the period in which the laser light source D1 emits light, as in the first embodiment. Is possible.

5 (a) to 5 (g) show signals of each part of the emission intensity reference signal generation substrate 101 when the sub-scanning direction position of the test pattern image shown in FIG. 1 is P2. The horizontal axis corresponds to the main scanning direction.

FIG. 5A shows a waveform of a multi-valued image signal.

FIG. 5B shows the waveform of the image PWM signal.

FIG. 5C shows the waveform of the shading correction signal.

FIG. 5D shows a waveform of a pulse density-modulated shading correction signal (PDM shading correction signal).

FIG. 5 (e) shows the waveform of the voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105. Initially it is V1 x R1 / (R1 + R2 + R3), but it rises towards V1 x R1 / (R1 + R2) while the black level continues. When it changes to the gray level, it descends toward V1 × R1 / (R1 + R2 + (1/2) · R3).

FIG. 5 (f) shows the waveform of the voltage of the output terminal of the switching circuit 107. This is the amplitude of the PDM shading correction signal shown in FIG. 5 (d) varied by the voltage shown in FIG. 5 (e).

FIG. 5 (g) shows the waveform of the voltage of the output terminal of the filter circuit 109. This is shown in FIG. 5 (c) as compared with FIG. 5 (c) in FIG. 7 (b) showing the input multi-valued image signal corresponding to FIG. 7 (a). With respect to the shading correction signal shown, the signal is increased as it advances in the main scanning direction by the amount varied by the voltage shown in FIG. 5 (e). Therefore, even if the black level continues as shown in FIG. 5A, the image level does not drop, and the subsequent gray level does not drop as compared with the correct gray level.

FIG. 6 shows signals of each part of the emission intensity reference signal generation substrate 101 when the sub-scanning direction position of the test pattern image shown in FIG. 1 is P1. The horizontal axis corresponds to the main scanning direction.

FIG. 6A shows the waveform of the multi-valued image signal.

FIG. 6B shows the waveform of the image PWM signal.

FIG. 6C shows the waveform of the shading correction signal.

FIG. 6D shows a waveform of a pulse density-modulated shading correction signal (PDM shading correction signal).

FIG. 6 (e) shows the waveform of the voltage of the common output terminal of the voltage dividing circuit 103 and the integrating circuit 105. Initially V1 × R1 / (R1 + R2 + R3), but V1 × R1 / (R1 + R2 + R3) is maintained for the duration of the white level. If it changes to the gray level, it rises toward V1 × R1 / (R1 + R2 + (1/2) · R3).

FIG. 6 (f) shows the waveform of the voltage of the output terminal of the switching circuit 107. This is the amplitude of the PDM shading correction signal shown in FIG. 5 (d) varied by the voltage shown in FIG. 5 (e).

FIG. 6 (g) shows the waveform of the voltage of the output terminal of the filter circuit 109.

7 is a collection of drawings excerpted from FIGS. 5 and 6 for comparison, FIG. 7 (a) corresponds to FIG. 5 (a), and FIG. 7 (b) is FIG. 5 ( c) and FIG. 5 (g), FIG. 7 (c) corresponds to FIG. 6 (a), and FIG. 7 (d) corresponds to FIGS. 6 (c) and 6 (g).

FIG. 7 (a) shows a multi-valued image signal in which the black level continues for a predetermined period and then the gray level continues, and FIG. 7 (b) shows a emission intensity reference signal corresponding to such the multi-valued image signal. However, this has a waveform in which the droop correction is added to the shading correction during the period in which the black level continues, and the droop correction is added to the shading correction even in the period in which the gray level continues.

FIG. 7 (c) shows a multi-valued image signal in which the white level continues for a predetermined period and then the gray level, and FIG. 7 (d) shows a emission intensity reference signal corresponding to such the multi-valued image signal. However, this has a waveform in which shading correction is performed but droop correction is not performed during the period in which the white level continues, and droop correction is added to the shading correction even in the period in which the gray level continues.

In particular, when the level of the emission intensity reference signal at the position where the gray level starts is compared with FIGS. 7 (b) and 7 (d), there is a difference due to the droop correction. Therefore, conventionally, there is a concentration difference between the region 901 and the region 903 as shown in FIG. 1, whereas according to the present embodiment, the region 905 and the region 907 are as shown in FIG. There is no difference in concentration between them.

[Third Embodiment]
The third embodiment is a digitization of the circuit included in the emission intensity reference signal generation substrate in the first embodiment in which the binary image signal is used as the input image signal. The digitized emission intensity reference signal generation circuit may be a digital IC circuit such as a PLD (Programmable Logic Device), a digital processor operated by an instruction, or a mixture of these. You may.

As shown in FIG. 9, the circuit included in the emission intensity reference signal generation substrate 101 in the first embodiment is largely replaced by the emission intensity reference signal generation circuit 201 that has been digitized.

Referring to FIG. 9, the emission intensity reference signal generation circuit 201 includes a voltage dividing circuit 203, an integrating circuit 205, an amplitude adjusting unit 207, a PDM circuit 123, a shading correction signal generation unit 211, a filter circuit 109, and a buffer 113. Of these, the parts other than the filter circuit 109 and the buffer 113 are digitized.

The voltage divider circuit 203 outputs a level that changes depending on the value of the binary image signal, and includes a holding unit 221 having a numerical value 128, a holding unit 223 having a density correction amplitude Ga, a switch SW11, and an adder 225. The output voltage of the voltage divider circuit 203 is 128 when the level of the binary image signal is LOW, and 128 + Ga when the level of the binary image signal is HIGH.

The integrator circuit 205 time-integrates the output voltage of the voltage divider circuit 203 that changes according to the level of the binary image signal, and includes a weighting circuit 227, 229, a synchronous delay circuit 231 and 233, and an adder 235. .. The weight of the weighting circuit 227 is the density correction time constant Gb, and the weight of the weighting circuit 229 is 1-Gb. The signal input from the voltage dividing circuit 203 is weighted by the weighting circuit 227 and delayed by one clock by the synchronous delay circuit 231, and then a feedback loop composed of the weighting circuit 229, the synchronous delay circuit 233 and the adder 235. Is output while gradually attenuating. Therefore, the output of the integrator circuit 205 fluctuates between 128 and 128 + Ga with an attenuation amount depending on the density correction time constant Gb, depending on the level of the binary image signal.

The shading correction signal generation unit 211 includes a shading correction signal generation table 241 similar to the shading correction signal generation table 121 in the first embodiment, and does not include a pulse density modulation circuit (PDM circuit).

The amplitude adjusting unit 207 is a multiplier for multiplying the output of the integrating circuit 205 and the output of the shading correction signal generation unit 211, and a multiplier for attenuating the output of the multiplier 243 so as to be 1/128 times. Includes a holding unit 247 that holds 245, 1/128. Therefore, the output of the amplitude adjusting unit 207 has a value obtained by multiplying the shading correction signal by the droop correction signal and then attenuating it to 1/128.

The PDM circuit 123 generates a pulse density modulated wave (PDM modulated wave) by applying ΔΣ modulation to the output of the amplitude adjusting unit 207. The output of the PDM circuit 123 when the output of the shading correction signal generation unit 211 is directly input to the PCM circuit 123 and the output of the shading correction signal generation unit 211 are passed through the amplitude adjustment unit 207 and then input to the PCM circuit 123. Comparing with the output of the PDM circuit 123 in this case, the difference is that the HIGH period of the PDM modulated wave output from the PDM circuit 123 fluctuates due to the amplitude adjustment by the amplitude adjusting unit 207.

This PCM signal is supplied to the filter circuit 109 for smoothing. The output of the filter circuit 109 is supplied to the laser light source substrate 131 as a emission intensity reference signal via the buffer 113.

In the laser light source substrate 131, the emission intensity reference signal is switched by the switch SW4 based on the binary image signal, thereby driving the laser light source D1.

Therefore, the laser light source D1 emits a laser beam with an emission intensity based on the emission intensity reference signal adjusted so as to perform shading correction and droop correction on the emission intensity reference signal generation substrate 201 during the period when the switch SW4 is turned on. It will be emitted.

FIG. 10 is a flowchart for explaining the operation when the voltage dividing circuit 203, the integrating circuit 205, and the amplitude adjusting unit 207 of the emission intensity reference signal generation board 201 are realized by a digital processor.

Referring to FIG. 10, first, the shading correction signal generation table 241 is set (step S301), the density correction amplitude Ga is set (step S303), and the density correction time constant Gb is set (step S305). This is the initial setting before production.

Next, if the main scan begins (YES in step S307), the variable N is initialized to 1 and the input Ei (0) and output Eo (0) of the integrator circuit 205 are set for the first step S317 to be executed. Set to 128 (step S309). Although not shown in FIG. 10, the amount of light is corrected by APC during the non-image formation period near the start of the main scan.

Next, it is examined whether or not the value of the current binary image signal is HIGH (step S311).

If it is HIGH (YES in step S311), 128 + Ga is set as the output of the voltage dividing circuit 203 (input of the integrating circuit 205) Ei (N) (step S313), and if it is LOW (NO in step S311). 128 is set as the output (input of the integrating circuit 205) Ei (N) of the voltage dividing circuit 203 (step S315).

After step S313 or step S315,
Eo (N) = (1-Gb) · Eo (N-1) + Gb · Ei (N-1)
The output Eo (N) of the integrating circuit 205 is obtained by the calculation of (step S317).

Next, the power command value is obtained by the following equation (step S319).

Power command value = Eo (N) / S (k) / 128
Here, S (k) is a shading correction signal obtained from the shading correction signal generation table 241 using the current beam horizontal position data k as a key.

Next, if the current main scan is not completed (NO in step S321), N is increased by 1 (step S323), and then the process returns to step S311.

If the current main scan is completed (YES in step S321) and the image formation is not completed (NO in step S323), the process returns to step S307.

The PDM circuit 123 may be operated by a digital signal processor in parallel with the PDM circuit 123.

Further, although the amplitude characteristic after passing through the filter circuit 109 in the subsequent stage is slightly deteriorated, a pulse width modulation circuit may be used instead of the PDM circuit (pulse density modulation circuit) 123.

[Fourth Embodiment]
The fourth embodiment is a digitization of the circuit included in the emission intensity reference signal generation substrate in the second embodiment in which the multi-valued image signal is used as the input image signal.

In the third embodiment, the image signal was a binary image signal. On the other hand, in the fourth embodiment, the image signal is a multi-valued image signal. In order to cope with this, in the fourth embodiment, as shown in FIG. 11, a PWM circuit 133 is added.

The PWM circuit 133 converts the multi-valued image signal into an image PWM signal. The image PWM signal is used to control the on / off of the switch SW4 on the laser light source substrate 131.

The voltage divider circuit 203B according to the fourth embodiment replaces the switch SW11 of the voltage divider circuit 203 according to the third embodiment with the multiplier 224, and further reduces the output level of the multiplier 224 to 1/16. A holding unit 222 with a numerical value of 1/16 and a multiplier 226 are added.

The multiplier 224 multiplies the numerical value Ga by the level of the binary image signal.

The configuration and operation of the other parts are the same as those in the third embodiment.

Therefore, in the fourth embodiment, even when a multi-valued image signal is input, the droop correction is performed according to the period in which the laser light source D1 emits light, as in the third embodiment. Is possible.

FIG. 12 is a flowchart for explaining the operation when the voltage dividing circuit 203B, the integrating circuit 205, and the amplitude adjusting unit 207 of the emission intensity reference signal generation board 201 are realized by a digital processor.

Referring to FIG. 12, first, the shading correction signal generation table 241 is set (step S301), the density correction amplitude Ga is set (step S303), and the density correction time constant Gb is set (step S305). This is the initial setting before production.

Next, if the main scan begins (YES in step S307), the variable N is initialized to 1 and the input Ei (0) and output Eo (0) of the integrator circuit 205 are set for the first step S317 to be executed. Set to 128 (step S309). Although not shown in FIG. 10, the amount of light is corrected by APC during the non-image formation period near the start of the main scan.

Next, it is examined whether or not the value of the current image PWM signal is HIGH (step S311B).

If it is HIGH (YES in step S311B), 128 + Ga · duty is set as the output of the voltage divider circuit 203 (input of the integrating circuit 205) Ei (N) (step S313B), and if it is LOW (NO in step S311B). ), 128 is set as the output (input of the integrating circuit 205) Ei (N) of the voltage dividing circuit 203 (step S315).

After step S313B or step S315,
Eo (N) = (1-Gb) · Eo (N-1) + Gb · Ei (N-1)
The output Eo (N) of the integrating circuit 205 is obtained by the calculation of (step S317).

Next, the power command value is obtained by the following equation (step S319).

Power command value = Eo (N) / S (k) / 128
Here, S (k) is a shading correction signal obtained from the shading correction signal generation table 241 using the current beam horizontal position data k as a key.

Next, if the current main scan is not completed (NO in step S321), N is increased by 1 (step S323), and then the process returns to step S311B.

If the current main scan is completed (YES in step S321) and the image formation is not completed (NO in step S323), the process returns to step S307.

The PDM circuit 123 may be operated by a digital signal processor in parallel with the PDM circuit 123.

[Fifth Embodiment]
In the fifth embodiment, in the first embodiment in which the binary image signal is used as the input image signal, the circuit included in the emission intensity reference signal generation substrate is digitized, and the droop is caused by the heat generation of the laser light source. The correction of the phenomenon and the correction of the droop phenomenon caused by the charge amount of the photoconductor are separated.

The droop phenomenon includes those caused by the heat generation of the laser light source and those caused by the fluctuation of the charge amount of the photoconductor, and the degree of both is different, and the temporal fluctuation is also different. However, in the first and second embodiments, both droop phenomena are corrected by a series of voltage dividing circuits and integrator circuits using one voltage dividing ratio and one time constant, and the third and third embodiments are used. In the fourth embodiment, both droop phenomena are collectively corrected by a series of voltage dividing circuits and an integrating circuit using one concentration correction amplitude Ga and one concentration correction time constant Gb.

The fifth embodiment is based on the third embodiment. Then, both droop phenomena are individually corrected by a two-series voltage dividing circuit and an integrating circuit using the two concentration correction amplitudes Ga1 and Ga2 and the two concentration correction time constants Gb1 and Gb2.

As shown in FIG. 13, two voltage dividing circuits 203-1 and 203-2 and two integrating circuits 205-1 and 205-2 are provided, and the outputs of the integrating circuits 205-1 and 205-2 are weighted. After weighting and adding by the units 208-1, 208-2 and the adder 206, the shading correction signal is multiplied by the sum of these. As the weighting by the weighting units 208-1 and 208-2, for example, 1/2 and 1/2 may be set, but other values may be set. Generally, it is W or 1-W. Throughout the specification, the portion having the tail portion -1 is related to the correction of the droop caused by the heat generation of the laser light source, and the portion having the tail portion -2 is related to the droop caused by the fluctuation of the charge amount of the photoconductor. Suppose it is a part.

FIG. 14 is for explaining the operation when the voltage dividing circuits 203-1 and 203-2, the integrating circuits 205-1 and 205-2, and the amplitude adjusting unit 207 of the emission intensity reference signal generation board 201 are realized by a digital processor. It is a flowchart of.

Referring to FIG. 14, first, the shading correction signal generation table 241 is set (step S301), the density correction amplitudes Ga1 and Ga2 are set (step S303C), and the density correction time constants Gb1 and Gb2 are set (step S305C). ). This is the initial setting before production.

Next, if the main scan begins (YES in step S307), the variable N is initialized to 1 and the inputs Ei1 (0) of the integrating circuits 205-1, 205-2 for the first step S317 to be executed. Ei2 (0), outputs Eo1 (0), and Eo2 (0) are set to 128 (step S309C). Although not shown in FIG. 10, the amount of light is corrected by APC during the non-image formation period near the start of the main scan.

Next, it is examined whether or not the value of the current binary image signal is HIGH (step S311).

If it is HIGH (YES in step S311), the outputs of the voltage dividing circuits 203-1 and 203-2 (inputs of the integrating circuits 205-1 and 205-2) are 128 + Ga1 and 128 + Ga1 as Ei1 (N) and Ei2 (N). (Step S313C), if it is LOW (NO in step S311), the outputs of the voltage divider circuits 203-1 and 203-2 (inputs of the integrator circuits 205-1 and 205-2) Ei1 (N) and Ei2. 128 and 128 are set as (N) (step S315C).

After step S313C or step S315C,
Eo1 (N) = (1-Gb) · Eo1 (N-1) + Gb · Ei1 (N-1)
Eo2 (N) = (1-Gb) / Eo2 (N-1) + Gb / Ei2 (N-1)
Eo (N) = W ・ Eo1 (N) + (1-W) ・ Eo2 (N)
The output Eo (N) of the integrating circuit 205 is obtained by the calculation of (step S317C).

Next, the power command value is obtained by the following equation (step S319).

Power command value = Eo (N) / S (k) / 128
Here, S (k) is a shading correction signal obtained from the shading correction signal generation table 241 using the current beam horizontal position data k as a key.

Next, if the current main scan is not completed (NO in step S321), N is increased by 1 (step S323), and then the process returns to step S311.

If the current main scan is completed (YES in step S321) and the image formation is not completed (NO in step S323), the process returns to step S307.

The PDM circuit 123 may be operated by a digital signal processor in parallel with the PDM circuit 123.

[Sixth Embodiment]
In the sixth embodiment, in the second embodiment in which the multi-valued image signal is used as the input image signal, the circuit included in the emission intensity reference signal generation substrate is digitized, and the droop is caused by the heat generation of the laser light source. The correction of the phenomenon and the correction of the droop phenomenon caused by the charge amount of the photoconductor are separated.

The sixth embodiment is configured based on the fourth embodiment in the same manner as the fifth embodiment is configured based on the third embodiment. As shown in FIG. 15, two voltage dividing circuits 203B-1 and 203B-2 and two integrating circuits 205-1 and 205-2 are provided, and the outputs of the integrating circuits 205-1 and 205-2 are added. After adding with the device 206, the shading correction signal is multiplied by the sum of these.

FIG. 16 is for explaining the operation when the voltage dividing circuits 203B-1, 203B-2, the integrating circuits 205-1 and 205-2, and the amplitude adjusting unit 207 of the emission intensity reference signal generation board 201 are realized by a digital processor. It is a flowchart of.

Referring to FIG. 16, first, the shading correction signal generation table 241 is set (step S301), the density correction amplitudes Ga1 and Ga2 are set (step S303D), and the density correction time constants Gb1 and Gb2 are set (step S305D). ). This is the initial setting before production.

Next, if the main scan begins (YES in step S307), the variable N is initialized to 1 and the inputs Ei1 (0) of the integrating circuits 205-1, 205-2 for the first step S317 to be executed. Ei2 (0), outputs Eo1 (0), and Eo2 (0) are set to 128 (step S309D). Although not shown in FIG. 10, the amount of light is corrected by APC during the non-image formation period near the start of the main scan.

Next, it is examined whether or not the value of the current image PWM image signal is HIGH (step S311D).

If it is HIGH (YES in step S311D), the outputs of the voltage dividing circuits 203B-1 and 203B-2 (inputs of the integrating circuits 205-1 and 205-2) are 128 + Ga1 · Duty as Ei1 (N) and Ei2 (N). , 128 + Ga1 · Duty is set (step S313D), if it is LOW (NO in step S311D), the output of the voltage divider circuits 203B-1 and 203B-2 (input of the integrator circuits 205-1 and 205-2) Ei1 ( 128 and 128 are set as N) and Ei2 (N) (step S315D).

After step S313D or step S315D,
Eo1 (N) = (1-Gb) · Eo1 (N-1) + Gb · Ei1 (N-1)
Eo2 (N) = (1-Gb) / Eo2 (N-1) + Gb / Ei2 (N-1)
Eo (N) = W ・ Eo1 (N) + (1-W) ・ Eo2 (N)
The output Eo (N) of the integrating circuit 205 is obtained by the calculation of (step S317D).

Next, the power command value is obtained by the following equation (step S319).

Power command value = Eo (N) / S (k) / 128
Here, S (k) is a shading correction signal obtained from the shading correction signal generation table 241 using the current beam horizontal position data k as a key.

Next, if the current main scan is not completed (NO in step S321), N is increased by 1 (step S323), and then the process returns to step S311.

If the current main scan is completed (YES in step S321) and the image formation is not completed (NO in step S323), the process returns to step S307.

The PDM circuit 123 and the filter circuit 109 may be operated in parallel with the PDM circuit 123 by a digital signal processor [7th embodiment].
In the seventh embodiment, in the first embodiment in which the binary image signal is used as the input image signal, the circuit included in the emission intensity reference signal generation substrate is digitized, and the droop is caused by the heat generation of the laser light source. The correction of the phenomenon and the correction of the droop phenomenon caused by the charge amount of the photoconductor are separated, and the initialization of the correction of the droop phenomenon caused by the heat generation of the laser light source and the droop phenomenon caused by the charge amount of the photoconductor are further separated. It is a separation of the initialization of the correction.

The configuration of the seventh embodiment is the same as the configuration of the fifth embodiment, as shown in FIG.

The operation of the seventh embodiment is as shown in FIG. 17, except that step S309C is replaced with step S309E as compared with the operation of the fifth embodiment shown in FIG.

In a fifth embodiment, as shown in FIG. 14, if the main scan has started (YES in step S307), the variable N is initialized to 1 and the integrator circuit 205 for step S317C to be executed first. The inputs Ei1 (0) and Ei2 (0) and the outputs Eo1 (0) and Eo2 (0) of -1, 205-2 are set to 128 (step S309C).

By the way, the light amount correction is performed by the APC in the non-image formation period near the start of the main scan.

In the seventh embodiment, since the input Ei1 (0) and the output Eo1 (0) are the initial values of the input / output of the integrating circuit 205-1 related to the correction of the droop caused by the heat generation of the laser light source, this initial value. Initialization to the value is performed at the same time as initialization of the laser light amount by APC.

Then, the initial value of the input / output of the integrating circuit 205-2 related to the correction of the droop caused by the charge amount of the photoconductor drum is set to the input / output of the integrating circuit 205-1 related to the correction of the droop caused by the heat generation of the laser light source. Avoid doing it at the same time as the initial value.

Therefore, as shown in FIG. 17, in the seventh embodiment, unlike the fifth embodiment, if the main scan starts (YES in step S307), the input Ei1 of the integrating circuit 205-1 (YES). 0) and the output Eo1 (0) are initialized, but the input Ei2 (0) and the output Eo2 (0) of the integrating circuit 205-2 are not initialized (step S309E). Therefore, the integrator circuit 205-2 does not change the input / output in steps when the main scan starts, and continues the integration operation up to that point.

Initialization of the input Ei2 (0) and the output Eo2 (0) of the integrating circuit 205-2 related to the correction of the droop caused by the charge amount of the photoconductor drum is appropriately performed as necessary. For example, it is performed at the same time as the correction of the charge amount of the photoconductor drum. This is not shown in FIG.

[Eighth Embodiment]
In the eighth embodiment, in the second embodiment in which the multi-valued image signal is used as the input image signal, the circuit included in the emission intensity reference signal generation substrate is digitized, and the droop is caused by the heat generation of the laser light source. The correction of the phenomenon and the correction of the droop phenomenon caused by the charge amount of the photoconductor are separated, and the initialization of the correction of the droop phenomenon caused by the heat generation of the laser light source and the droop phenomenon caused by the charge amount of the photoconductor are further separated. It is a separation of the initialization of the correction.

The configuration of the eighth embodiment is the same as the configuration of the sixth embodiment, as shown in FIG.

The operation of the eighth embodiment is as shown in FIG. 18, except that step S309D is replaced with step S309F as compared with the operation of the sixth embodiment shown in FIG.

In the sixth embodiment, as shown in FIG. 16, if the main scan has started (YES in step S307), the variable N is initialized to 1 and the integrator circuit 205 for step S317D to be executed first. The inputs Ei1 (0) and Ei2 (0) and the outputs Eo1 (0) and Eo2 (0) of -1, 205-2 are set to 128 (step S309D).

By the way, the light amount correction is performed by the APC in the non-image formation period near the start of the main scan.

In the eighth embodiment, as in the seventh embodiment, the input Ei1 (0) and the output Eo1 (0) are input to the integration circuit 205-1 relating to the correction of the droop caused by the heat generation of the laser light source. Since it is the initial value of the output, the initialization to this initial value is performed at the same time as the initialization of the laser light amount by the APC.

Then, the initial value of the input / output of the integrating circuit 205-2 related to the correction of the droop caused by the charge amount of the photoconductor drum is set to the input / output of the integrating circuit 205-1 related to the correction of the droop caused by the heat generation of the laser light source. Avoid doing it at the same time as the initial value.

Therefore, as shown in FIG. 18, in the eighth embodiment, as in the seventh embodiment, if the main scan starts (YES in step S307), the input Ei1 of the integrating circuit 205-1 (YES). 0) and the output Eo1 (0) are initialized, but the input Ei2 (0) and the output Eo2 (0) of the integrating circuit 205-2 are not initialized (step S309F). Therefore, the integrator circuit 205-2 does not change the input / output in steps when the main scan starts, and continues the integration operation up to that point.

Initialization of the input Ei2 (0) and the output Eo2 (0) of the integrating circuit 205-2 related to the correction of the droop caused by the charge amount of the photoconductor drum is appropriately performed as necessary. For example, it is performed at the same time as the correction of the charge amount of the photoconductor drum. This is not shown in FIG.

[9th embodiment]
The filters used in the first to eighth embodiments are merely examples. It may be a first-order low-pass filter or may have other configurations. Further, other types of filters may be used.

In the fifth to eighth embodiments, two series of voltage divider circuits and filters are used, but there may be three or more series.

In the third to eighth embodiments, the discretized circuit constants the concentration correction amplitude Ga (or Ga1 and Ga2) and the concentration correction time constant Gb (or Gb1 and Gb2) are changed according to the environment and life. ..

These changes can be made by measuring the toner concentration with a sensor included in the process controller using a test pattern image or the like. That is, the sensor included in the process controller can measure the amount of toner adhering to the photoconductor drum, which can be used to measure the amount of toner corresponding to a predetermined position in the test pattern image. .. For example, the amount of toner corresponding to some predetermined position of the test pattern image can be measured. Then, the circuit constant can be adjusted so that the amount of toner at these positions both becomes a desired value.

According to the above embodiment, the shading correction is performed by the filtering process of the PDM wave, and the peak value of the PDM wave is increased or decreased according to the ON / OFF of the data signal, so that the following effect is obtained.
-Since it is configured not to refer to the table for droop correction, it does not require a lot of memory capacity.
-Drop correction can be performed correctly even in the case of multi-valued image signals.
・ Shading correction can be performed at the same time as droop correction.

[10th Embodiment]
A tenth embodiment relates to a multifunction device 800 including a document reading device according to the first to ninth embodiments. 19 and 20 show the configuration of the multifunction device 800 and the like.

As shown in FIGS. 19 and 20, the multifunction device 800 includes a document reading device 820 that reads an image of a document, a multifunction device main body (image forming unit main body) 830 that forms an image on a sheet, and a document reading device 820 and a composite. It includes an operation panel unit 843 for operating the machine main body 830, and an arithmetic processing unit 841 for controlling the document reading device 820 and the multifunction device main body 830 based on the operation by the operation panel unit 843.

In addition to using the document reading device 820 as a single unit for image reading and using the multifunction device main body 830 as a single unit for image formation, these can also be linked to copy an image. Further, the multifunction device 800 may include a storage device and a facsimile machine (not shown). The storage device can store the image read by the document reading device 820 and the image received by the facsimile machine. The facsimile machine can transmit the image read by the document reading device 820 and the image stored in the storage device, and can receive the image from the outside. Further, the multifunction device 800 may include an interface for connecting to a personal computer via a network. The personal computer connected to the multifunction device 800 can use the function of the multifunction device for the data that can be managed by the personal computer.

The document reading device 820 includes a document automatic feeding unit SPF (Single Pass Feeder) 824 that automatically feeds documents, and a reading device main body 822 that reads images of documents. In addition to the components shown in FIG. 20, the document reading device 820 also includes components not shown in FIG. 20 but shown in FIG. Further, as shown in FIG. 19, the reading device main body 822 is provided with a document base 826.

The multifunction device main body 830 includes a sheet feeding section 10 for feeding the sheet, a manual feeding section 20 capable of manually feeding the sheet, and a sheet fed by the sheet feeding section 10 or the manual feeding section 20. An image forming unit 30 for forming an image is provided.

The sheet feeding unit 10 includes a sheet loading unit 11 for loading sheets and a separate feeding unit 12 for separately feeding the sheets loaded on the sheet loading unit 11 one by one. The seat loading portion 11 includes a middle plate 14 that rotates about a rotation shaft 13, and the middle plate 14 rotates when feeding the seat and lifts the seat upward. The separate feeding unit 12 includes a pickup roller 15 that feeds the sheet lifted by the middle plate 14, and a separation roller pair 16 that separates the sheets fed by the pickup roller 15 into one sheet at a time. ..

The manual feed feeding unit 20 includes a manual feed tray 21 capable of loading sheets, and a separate feed unit 22 for separately feeding the sheets loaded on the manual feed tray 21 one by one. The manual feed tray 21 is rotatably supported by the multifunction device main body 830, and when manually feed and feed, the sheet can be loaded by fixing the manual feed tray 21 at a predetermined angle. The separation feeding unit 22 includes a pickup roller 23 for feeding the sheets loaded on the manual feed tray 21, a separation roller 24 and a separation pad 25 for separating the sheets fed by the pickup roller 23 one by one. I have.

The image forming unit 30 includes four process cartridges 31Y to 31K for forming images of yellow (Y), magenta (M), cyan (C), and black (K), and photoconductor drums 740Y to 740K described later. 32, a transfer unit (transfer means) 33 for transferring the toner image formed on the surface of the photoconductor drums 740Y to 740K to the sheet, and a fixing unit 34 for fixing the transferred toner image to the sheet. And have. The alphabet (Y, M, C, K) attached to the end of the code indicates each color (yellow, magenta, cyan, black).

Each of the four process cartridges 31Y to 31K is configured to be removable from the multifunction device main body 830 and is replaceable. Since the four process cartridges 31Y to 31K have the same configuration except that the colors of the images to be formed are different, only the configuration of the process cartridge 31Y forming the yellow (Y) image will be described, and the process cartridge 31M will be described. The description of ~ 31K will be omitted.

The process cartridge 31Y includes a photoconductor drum 740Y as an image carrier, a charger 741Y for charging the photoconductor drum 740Y, a developing device 742Y for developing an electrostatic latent image formed on the photoconductor drum 740Y, and a photosensitizer. It includes a drum cleaner that removes toner remaining on the surface of the body drum 740Y. The developing device 742Y includes a developing device main body (not shown in detail) for developing the photoconductor drum 740Y, and a toner cartridge (not shown in detail) for supplying toner to the developing device main body. The toner cartridge is configured to be removable from the developing device main body, and when the stored toner is exhausted, the toner cartridge can be removed from the developing device main body and replaced.

The exposure apparatus 32 includes a light source (not shown) that irradiates the laser beam, and a plurality of mirrors (not shown) that guide the laser beam to the photoconductor drums 740Y to 740K. The transfer unit 33 includes an intermediate transfer belt 35 that carries a toner image formed on the photoconductor drums 740Y to 740K, and a primary transfer roller that primarily transfers the toner image formed on the photoconductor drums 740Y to 740K to the intermediate transfer belt 35. It includes 36Y to 36K, a secondary transfer roller 37 that secondarily transfers the toner image transferred to the intermediate transfer belt 35 to the sheet, and a belt cleaner 38 that removes the toner remaining on the intermediate transfer belt 35. The intermediate transfer belt 35 is hung on the drive roller 39a and the driven roller 39b, and is pressed against the photoconductor drums 740Y to 740K by the primary transfer rollers 36Y to 36K. The secondary transfer roller 37 nips (sandwiches) the intermediate transfer belt 35 with the drive roller 39a, and transfers the toner image carried by the intermediate transfer belt 35 to the sheet at the nip portion N. The fixing portion 34 includes a heating roller 34a that heats the sheet and a pressure roller 34b that presses against the heating roller 34a.

The operation panel unit 843 includes a display unit 845 that displays predetermined information, and an input unit 847 that allows the user to input instructions to the document reading device 820 and the multifunction device main body 830. In the present embodiment, the operation panel unit 843 is arranged on the front side of the reading device main body 822. The front side corresponds to the front side of the paper surface of FIG. 19, and the back surface side corresponds to the back side of FIG.

As shown in FIG. 20, the arithmetic processing unit 841 includes a CPU 841a that drives and controls a sheet feeding unit 10, a manual feeding unit 20, an image forming unit 30, and a document reading device 820, and various programs for operating the CPU 841a. It is provided with a memory 841b for storing various information and the like used by the CPU 841a. The arithmetic processing unit 841 integrates and controls the operations of the sheet feeding unit 10, the manual feeding unit 20, the image forming unit 30, and the document reading device 820 based on the operation of the user to the operation panel unit 843. Form an image on the sheet.

Next, an image forming operation (image forming control by the arithmetic processing unit 841) by the multifunction device 800 configured as described above will be described. In the present embodiment, the image forming unit 30 forms the image of the scanned document fed by the document automatic feeding unit 824 and read by the reading device main body 822 on the sheet fed by the sheet feeding unit 10. An image forming operation will be described as an example.

When the image formation start signal is transmitted by the input to the input unit 847 of the operation panel unit 843 by the user, the scanned document placed on the document automatic feeding unit 824 by the user is automatically directed toward the document reading position. The image is fed and the image is read by the reading device main body 822 at the document reading position.

When the image of the document is read by the reading device main body 822, the exposure device 32 irradiates the photoconductor drums 740Y to 740K with a plurality of corresponding laser beams based on the image information of the scanned document. At this time, the photoconductor drums 740Y to 740K are precharged by the chargers 741Y to 741K, respectively, and when the corresponding laser beams are irradiated, the respective electrostatic latent latent images are placed on the photoconductor drums 740Y to 740K. An image is formed. After that, the electrostatic latent images formed on the photoconductor drums 740Y to 740K are developed by the developing devices 742Y to 742K, and yellow (Y), magenta (M), and cyan (C) are developed on the photoconductor drums 740Y to 740K. ) And black (K) toner images are formed. The toner images of each color formed on the photoconductor drums 740Y to 740K are superimposed and transferred to the intermediate transfer belt 35 by the primary transfer rollers 36Y to 36K, and the superimposed transfer toner image (full-color toner image) is the intermediate transfer belt. It is conveyed to the nip portion N while being carried on the 35.

In parallel with the image forming operation described above, the sheets loaded on the sheet loading section 11 are fed to the sheet transport path 26 by the pickup roller 15 while being separated one by one by the separate feeding section 12. Then, the resist roller pair 27 located upstream in the sheet transport direction of the nip portion N corrects the skew and is conveyed to the nip portion N at a predetermined transfer timing. A full-color toner image carried by the intermediate transfer belt 35 is transferred to the sheet conveyed to the nip portion N by the secondary transfer roller 37.

The sheet to which the toner image is transferred is heated and pressurized by the fixing portion 34 to melt and fix the toner image, and is discharged to the outside of the device by the discharge roller pair 18. The sheet discharged to the outside of the device is loaded on the discharge sheet loading unit 19.

When an image is formed on both sides (first surface and second surface) of the sheet, the discharge roller pair 18 is rotated in the reverse direction before the sheet having the image formed on the first surface is discharged to the outside of the apparatus. It is transported to the double-sided transport path 17, and is re-transported to the image forming unit 30 via the double-sided transport path 17. Then, as with the first surface, an image is formed on the second surface and discharged to the outside of the device. The sheet discharged to the outside of the device is loaded on the discharge sheet loading unit 19.

The exposure apparatus 32 includes a laser light source substrate 131, and the light source in the exposure apparatus is the laser light source D1. The emission intensity reference signal generation substrate 101 may be included in the exposure apparatus 32, or at least a part thereof may be included in the arithmetic processing unit 841.

The above emission intensity reference signal generation device can be realized by hardware, software, or a combination thereof. Further, the emission intensity reference signal generation method performed by the above emission intensity reference signal generation device can also be realized by hardware, software, or a combination thereof. Here, what is realized by software means that it is realized by a computer reading and executing a program.

Programs can be stored and supplied to a computer using various types of non-transitory computer readable medium. Non-temporary computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg, flexible disks, magnetic tapes, hard disk drives), optomagnetic recording media (eg, optomagnetic disks), CD-ROMs (Read Only Memory), CD-. Includes R, CD-R / W, semiconductor memory (eg, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be supplied to the computer by various types of transient computer readable medium. Examples of temporary computer readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

The present invention can be practiced in various other forms without departing from its spirit or key features. Therefore, each of the above embodiments is merely an example and should not be construed in a limited manner. The scope of the present invention is shown by the scope of claims and is not bound by the text of the specification. Further, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

The present invention can be used to drive a laser light source.

101 Emission intensity reference signal generation board 103 Voltage divider circuit 105 Integration circuit 107 Switching circuit 109 Filter circuit 111 Shading correction signal generation unit 131 Laser light source board D1 Laser light source

Claims (16)

A droop correction signal generation means that generates a droop correction signal that is a signal whose waveform amplitude fluctuates based on the level of an image signal input from the outside and is a correction value for correcting the droop characteristics .
An amplitude modulation means that modulates the amplitude of the waveform of the shading correction signal by multiplying the droop correction signal in which the amplitude of the waveform fluctuates with the shading correction signal which is a correction value of the shading pattern by a multiplier .
An emission intensity reference signal generation means that generates an emission intensity reference signal that serves as a reference for the emission intensity of the emitted laser beam based on the shading correction signal in which the amplitude of the waveform is modulated by the amplitude modulation means.
A light emission intensity reference signal generation device comprising. The emission intensity reference signal generation device according to claim 1.
The shading correction signal is represented by a pulse density modulation signal.
The amplitude modulation means modulates the amplitude of the pulse density modulation signal.
The emission intensity reference signal generation device is characterized by comprising a low frequency pass filter that passes a low frequency component of a pulse density modulation signal whose amplitude is modulated by the amplitude modulation means. The emission intensity reference signal generation device according to claim 1.
The shading correction signal is represented by a pulse width modulation signal.
The amplitude modulation means modulates the amplitude of the pulse width modulation signal.
The emission intensity reference signal generation device is characterized by comprising a low frequency pass filter that passes a low frequency component of a pulse width modulation signal whose amplitude is modulated by the amplitude modulation means. The emission intensity reference signal generation device according to claim 1.
The shading correction signal is represented by a baseband signal.
The amplitude modulation means modulates the amplitude of the baseband signal.
The emission intensity reference signal generation means is
A pulse density modulation means for pulse density modulation of a baseband signal whose amplitude is modulated by the amplitude modulation means,
A low-pass filter that passes low-pass components of the output signal of the pulse density modulation means,
A light emission intensity reference signal generation device comprising. The emission intensity reference signal generation device according to claim 1.
The shading correction signal is represented by a baseband signal.
The amplitude modulation means modulates the amplitude of the baseband signal.
The emission intensity reference signal generation means is
A pulse width modulation means for pulse width modulation of a baseband signal whose amplitude is modulated by the amplitude modulation means,
A low-pass filter that passes low-pass components of the output signal of the pulse width modulation means,
A light emission intensity reference signal generation device comprising. The emission intensity reference signal generator according to any one of claims 1 to 5.
The droop correction signal generation means is an emission intensity reference signal generation device, characterized in that the droop correction signal is generated by time-integrating two levels switched by the image signal represented by a binary value. The emission intensity reference signal generator according to any one of claims 1 to 5.
The droop correction signal generation means is characterized in that the droop correction signal is generated by time-integrating two levels switched by a pulse width modulation signal obtained by pulse width modulation of the image signal represented by multiple values. Emission intensity reference signal generator. The emission intensity reference signal generator according to any one of claims 1 to 5.
The droop correction signal generation means has one of two levels switched by a pulse width modulation signal obtained by pulse width modulation of the image signal represented by multiple values, and the pulse width modulation with respect to the other. An emission intensity reference signal generation device, characterized in that the droop correction signal is generated by time-integrating the value obtained by multiplying the duty of the signal. The emission intensity reference signal generator according to any one of claims 1 to 8.
A emission intensity reference signal generation device, characterized in that the circuit constants of the droop correction signal generation means are held as digital data in a changeable manner. The emission intensity reference signal generator according to claim 9.
An emission intensity reference signal generation device comprising further means for changing the circuit constant based on measurement data related to an image formed by using a light source that emits light based on the emission intensity reference signal. The emission intensity reference signal generator according to any one of claims 1 to 10.
The droop correction signal generation means is a emission intensity reference signal generation device, characterized in that it includes a plurality of sequences corresponding to each of a plurality of types of droops. The emission intensity reference signal generation device according to claim 11.
A emission intensity reference signal generation device further comprising a droop correction signal initialization means for initializing the droop correction signal of a predetermined series independently of other series. An image forming apparatus comprising the emission intensity reference signal generation apparatus according to any one of claims 1 to 12. A multifunction device comprising the emission intensity reference signal generation device according to any one of claims 1 to 12. A droop correction signal generation step that generates a droop correction signal, which is a correction value for correcting droop characteristics, in which the amplitude of the waveform fluctuates based on the level of the image signal input from the outside .
An amplitude modulation step in which the droop correction signal in which the amplitude of the waveform fluctuates and the shading correction signal which is a correction value of the shading pattern are multiplied by a multiplier, whereby the amplitude of the waveform of the shading correction signal is modulated .
An emission intensity reference signal generation step that generates an emission intensity reference signal that serves as a reference for the emission intensity of the emitted laser beam based on the shading correction signal in which the amplitude of the waveform is modulated in the amplitude modulation step .
A method for generating a emission intensity reference signal. A program for operating a computer as the emission intensity reference signal generator according to any one of claims 1 to 12.

Images