JP3279413B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, for example, an image forming apparatus such as a printer, a copying machine, and a facsimile which forms an electrostatic latent image by irradiating a photosensitive member with a laser.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a conventional apparatus, and FIG. 6 is a flowchart showing image forming sequence control, which will be described below.

A print signal (a) for controlling the start or continuation of printing of the image forming apparatus is connected to the microprocessor 1 from the video controller 2. When the print signal (a) is enabled (S1), the microprocessor 1 controls a drive sequence of the image forming apparatus.
Recognizes the start of printing or the continuation of printing, rotates the developing cylinder 1601 and the motor 705 provided in the photosensitive member 19 and the developing device 16 (S2), and causes the primary charger 14 to rotate the photosensitive member 19. Charge the surface uniformly. Further, the pickup roller 21 rotates once and the feed 22 rotates (S3), and the recording material W provided in the cassette 20 is conveyed into the image forming apparatus. The recording material detection element 23 disposed near the registration roller 24 detects that the recording material W has been conveyed, and the conveyance detection signal (q) output from the recording material conveyance detection circuit 12 generates The microprocessor 1 detects the conveyance of the recording material W (S4). After detecting the conveyance of the recording material W, the microprocessor 1 stops the rotation of the feed roller 22 after a predetermined time necessary for the recording material W to be conveyed to the registration roller 24 (S5), and conveys the recording material W (S6). Interrupt.

Thereafter, the microprocessor 1 operates in accordance with the flowchart showing the laser light output adjustment shown in FIG.
The laser light output is adjusted (S7).

The microprocessor 1 sets a light amount control signal (n) for controlling the operating current of the laser to a default value (S701), and sends the light amount control signal (n) via a buffer latch circuit 8 and a D / A converter 9. ) Is input to the laser drive circuit 6. The laser drive circuit 6 includes a constant current circuit 601 for supplying a laser operation current proportional to the light amount control signal (n), and a switching circuit 602 for performing ON / OFF control of the laser by the laser drive signal (j). . The microprocessor 1 turns on the laser drive signal (j) by turning on the APC request signal (g) (S702), and continuously turns on the laser. At this time, the light output of the semiconductor laser 701 is detected by a photodiode disposed in the package of the semiconductor laser 701, amplification and current-voltage conversion are performed by the light amount detection circuit 11, and the detection is performed via the A / D converter 10. The light amount signal (p) is input to the microprocessor 1.

The microprocessor 1 which has detected the light output of the laser calculates an output light amount error E (= Pref-P) between the light output reference value Pref and the detected light amount value P (S70).
3).

If the detected light amount P of the laser light output is smaller than the light output reference value Pref, the output light amount error E becomes a positive value (S704 → S705). At this time, if the detected light amount value P does not reach 90% of the optical output reference value Pref, the output light amount error E becomes Pref / 1.
Since the value is larger than 0, the magnitude of I1 is increased in the light amount control signal (n) (S706), and the laser light output is increased. In this sequence, the detected light amount P is equal to the light output reference value Pre.
This is repeated until 90% of f is reached. And
The increased detection light amount value P is 90% of the light output reference value Pref.
When the value falls within the range of values smaller than 95%, the output light amount error E satisfies Pref / 20 ≦ E <Pref / 10, and the light amount control signal (n) increases the magnitude of I2 (S70).
7). I2 is smaller than I1 to improve the resolution of the light intensity control signal. This sequence is repeated until the detected light amount P reaches 95% or more of the light output reference value Pref. When the increased detected light amount value P is 95% or more of the light output reference value Pref, the light output reference value Pre
When the value falls within a range of values smaller than f, the output light amount error E becomes E ≦ E ≦
Pref / 20, and the magnitude of I3 is increased in the light amount control signal (n) (S708). I3 takes a smaller value than I2, further improving the resolution of the light quantity control signal (n). This sequence is repeated until the detected light amount P reaches or exceeds the light output reference value Pref. When the increased detected light amount P reaches the light output reference value Pref, the light amount control signal value at that time is latched by the buffer latch circuit 8. (S704 → S709), the light quantity control signal (n) output from the D / A converter 9 holds a constant value. Therefore, since a desired laser light output is obtained, the APC request signal (g) is turned off (S710), and the laser is turned off.

Further, when the resolution of the laser beams I1 and I2 is insufficient due to variations in the laser characteristics and the detected light amount P of the laser light output becomes larger than the light output reference value Pref, the output light amount error E becomes negative. Value. At this time, the light amount control signal (n) reduces the magnitude of I3 (S704 → S
711), the laser light output is reduced. This sequence is repeated until the detected light amount value P is equal to or smaller than the light output reference Pref, that is, the output light amount error E becomes E ≧ 0 (S71).
1, S712, S713), when the output light amount error E becomes E ≧ 0, the light amount control signal value is latched by the buffer latch circuit 8, and the light amount control signal (n) output from the D / A converter 9 is kept constant. Value. Therefore, since a desired laser light output or a laser light output close to the desired laser light output can be obtained, the APC request signal (g) is turned off and the laser is turned off.

The microprocessor 1 completes the laser light output adjustment (S7), and the motor ready signal (m) indicating that the PLL circuit provided in the polygon motor drive circuit 708 is locked on is ON. Then, the horizontal synchronization control signal (f) is turned ON (S9). Horizontal synchronization request circuit 3 receiving the horizontal synchronization control signal (f)
Turns on the horizontal synchronization request signal (h) and turns on the laser. A laser beam emitted from this laser passes through a collimator lens 702 and a cylindrical lens 703 and irradiates a polygon mirror 704. Since the polygon mirror 704 is rotated at a constant speed by the motor 705, the laser beam reflected by the polygon mirror 704 scans the surface of the photoconductor 19 through the toric lens 706 and the fθ lens 707. At this time, the laser beam is received by the light receiving element 15 disposed at the end of the photosensitive member 19, and the horizontal synchronization signal (e) is output by the horizontal synchronization detection circuit 13.
Is obtained. When the horizontal synchronization signal (e) is obtained, (S
10), the horizontal synchronization request circuit 3 turns off the horizontal synchronization request signal within a predetermined time T1, and turns off the laser. Also,
After a predetermined time T2, the horizontal synchronization request signal is turned on and the laser is turned on to obtain the next horizontal synchronization signal.

When the horizontal synchronizing signal (e) is obtained, the microprocessor 1 determines that the preparation for image formation has been completed, and sends the video controller 2 the tip of the recording material W and the photosensitive member 1 to the video controller 2.
9, a vertical synchronization request signal (b) for requesting a vertical synchronization signal (c) for matching with the top of the image on S9 (S1).
1).

When the video controller 2 receives the vertical synchronizing request signal (b), it transmits a vertical synchronizing signal (c) to the microprocessor 1 when it is ready to transmit an image signal. The image signal (d) is output in synchronization with (e).

When the microprocessor 1 receives the vertical synchronizing signal (c) (S12), the registration roller 24 starts rotating and the recording material W is conveyed (S13). Further, the laser drive circuit 6 supplies a laser operation current according to the light amount control signal (n) output from the microprocessor 1,
The laser drive current (k) turned on / off by the image signal (d) is supplied to the semiconductor laser 701. A laser beam emitted from the semiconductor laser 701 passes through a collimator lens 702 and a cylindrical lens 703, and irradiates a polygon mirror 704. Since the polygon mirror 704 is rotated at a constant speed by the motor 705, the laser beam reflected by the polygon mirror 704 scans the surface of the photoconductor 19 through the toric lens 706 and the fθ lens 707. By this laser beam, an electrostatic latent image is formed on the surface of the photoconductor 19, and the developing cylinder 1
The toner is transferred to the surface of the photoconductor 19 by 601 to form a toner image on the surface of the photoconductor 19. Then, the toner image is transferred onto the recording material W by the transfer charger 17 on the conveyed recording material W. The toner image transferred to the recording material W is heat-fixed to the recording material W by the fixing device 25, and is discharged to the outside of the image forming apparatus by the discharge roller 26. The residual toner remaining on the surface of the photoreceptor 19 is
And ready for new image formation.

After the time required for completing the image forming process on the recording material has elapsed (S14), the microprocessor 1 turns off the horizontal synchronization control signal (S1).
5) Stop laser lighting for obtaining a horizontal synchronizing signal.

In order to continuously form an image on the recording material of the next page, if the print signal (a) is enabled (S16), the above-described sequence control for image formation is repeated, and the print signal (a) is repeated. If a) is disabled, each drive system is stopped (S17), and waits until the print signal (a) indicating the start of the next image formation is enabled.

[0015]

As described above,
As means for keeping the output light quantity of the semiconductor laser uniform, 1
Each time an image is formed on a page recording material, the operating current of the semiconductor laser is set, and the laser light output is maintained uniformly by maintaining this value.

However, when the laser is turned on while the laser operating current Iop supplied to the laser is constant, the temperature of the laser oscillation region rises and the current-light output characteristic shifts in the current axis direction as shown in FIG. , The operating point is Qop →
The transition is made from Q1 to Q2, and the light output is reduced. Therefore, when the laser is turned on / off in response to the image signal, the temperature of the laser oscillation region fluctuates, and the light output changes as shown in FIG.

At this time, the relationship between the laser light output and the image density has the relationship shown in FIG. 10, and the recording image density changes as the laser light output changes. Therefore, when an image of a large size is formed, a difference occurs between the output light amount of the laser at the beginning and the end of the writing of the electrostatic latent image on the photosensitive member, and there is a problem that density unevenness occurs in the recorded image.

In the halftone expression, a pulse modulation method for controlling the lighting time of a laser is frequently used. The relationship between the pulse width, which is the laser lighting time, and the image density is shown in FIG.
The relationship shown in Fig. 1 indicates that the laser light output decreases,
There is a problem that the gradation property of the low-density image is lost, and that the laser light output fluctuates, so that gradation reproduction characteristics with linearity cannot be obtained.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus capable of compensating for a change in optical output due to a droop characteristic of a laser with high resolution.

[0020]

In order to achieve the above object, the present invention relates to a detection method for detecting the light output of a laser in an image forming apparatus for irradiating a photosensitive member with a laser to form an electrostatic latent image. Means, a first control means for outputting a first light quantity control signal for instructing a laser operation current so that the light output of the laser becomes a reference value, and a detection value outputted from the light quantity detection means. A second control unit that outputs a second light amount control signal representing a laser operation current to be added to a laser operation current based on the first light amount control signal based on an error from the reference value; Supply means for supplying, to the laser, a laser operation current representing an addition of the laser operation current indicated by the control signal and the laser current indicated by the second light quantity control signal; and the first control means controlling the first light quantity control signal Variable level control Periods have, is characterized in that comprises a reset means for resetting the second light quantity control signal.

[0021]

According to the present invention, the laser beam output during image formation is always optimally controlled so that there is no density unevenness.

[0022]

【Example】

<Embodiment 1> FIG. 1 is a block diagram of the apparatus according to the present embodiment (other components are the same as those in FIG. 5 and are not shown), and FIG.
The same components as those described above are denoted by the same reference numerals. Hereinafter, the configuration and operation will be described.

The configuration of the apparatus is roughly divided into a laser drive circuit 6 and first and second light quantity control signal setting means for controlling the operating current of the laser.

The laser drive circuit 6 supplies a constant current circuit 601 for supplying a laser operation current proportional to the third light quantity control signal (u) and a laser operation current supplied from the constant current circuit 601 by the laser drive signal (j). It comprises a switching circuit 602 for switching.

The third light quantity control signal (u) is a signal obtained by adding a first light quantity control signal (s) and a second light quantity control signal (t) described later by an adder 34.

Next, the second light quantity control signal (t) output by the second light quantity control signal setting means will be described.

The second light quantity control signal setting means detects the light output of the semiconductor laser 701 by a photodiode provided in the package of the semiconductor laser 701, and the light quantity detection circuit 11 performs amplification and current-voltage conversion. The detected light quantity signal (p) and the optical output reference value Po for output under software control of the microprocessor 1, which are output via the buffer latch circuit 27 and the D / A converter 28, An error amplifier comprising a subtractor 29 that subtracts the output light output reference value Po held by the above to obtain an output light quantity error E2 of the semiconductor laser, and an amplifier 30 that amplifies the output light quantity error E2. Having a part.

The output light amount error E2 output from the amplifier 30 is input to an integrator 33 that performs charging and discharging with a constant time constant via a sampling circuit 31 that performs sampling by a sampling control signal (r).

The AND circuit 3201 ANDs the image control signal (g) with the image signal (d) output from the video controller 2 and the signal obtained by delaying the image signal (d) by the delay circuit 3202. This indicates the timing when the laser is on, and is output from the timing generation circuit 32.

Therefore, the output light amount error E2 when the laser is turned on is input to the integrator 33 based on the image signal, and the integration result becomes the second light amount control signal (t). .

The integrator 33 has a reset circuit for discharging the charged electric charge in response to an integrator reset signal (v) from the microprocessor 1.
By enabling the integrator reset signal (v),
The second light quantity control signal will be reset.

Next, the first light quantity control signal (s) output by the first light quantity control signal setting means will be described.

An arbitrary value is output by software control of the microprocessor 1, the value is held in a buffer latch circuit 8, and the held value is converted into an analog signal by a D / A converter 9. This is a light amount control signal.

When the print signal (a) is enabled by the video controller 2 as described in the conventional example, the microprocessor 1 conveys the recording material W provided in the cassette 20 into the apparatus and reaches the registration roller 24. When transported, the laser light output is adjusted. Hereinafter, the laser light output adjusting method will be described with reference to FIG.

The microprocessor 1 resets the second light quantity control signal (t) to generate an integrator reset signal (v).
Is enabled (S714). Therefore, since the third light amount control signal (u) is equal to the first light amount control signal (s) and the laser drive circuit 6 that supplies a laser operation current proportional to the third light amount control signal (u) is provided, The light output of the semiconductor laser 701 is controlled by the first light amount control signal (s).

Then, the microprocessor 1 sets the first light quantity control signal (s) to a default value (S70).
1), turns on the APC request signal (g) (S702),
The semiconductor laser 701 is continuously turned on. At this time, the light output of the semiconductor laser 701 is detected by a photodiode provided in the package of the semiconductor laser 701, and the light amount detection circuit 11 performs amplification and current-voltage conversion.
The detected light amount signal (p) is input to the microprocessor 1 via the / D converter 10.

The microprocessor 1 having detected the laser light output calculates an output light amount error E (= Pref-P) between the light output reference value Pref and the detected light amount value P (S70).
3).

If the detected light amount value P of the laser light output is smaller than the light output reference value Pref, the output light amount error E becomes a positive value (S704 → S705). At this time, if the detected light amount value P does not reach 90% of the optical output reference value Pref, the output light amount error E becomes Pref / 1.
Since the value is larger than 0, the first light amount control signal (s) has I1
Is increased (S706), and the laser light output is increased. In this sequence, the detected light amount P is equal to the light output reference value Pr.
It repeats until it reaches 90% or more of ef. Then, the increased detected light amount value P is 9 of the light output reference value Pref.
When the output light quantity error E falls within the range of 0% or more and less than 95%, the output light quantity error E becomes Pref / 20 ≦ E <Pref / 10, and the magnitude of I2 is increased to the first light quantity control signal (s) (S707). The value I2 is smaller than the value I1, thereby improving the (s) resolution of the first light intensity control signal. In this sequence, the detected light amount P is equal to the light output reference value Pre.
This is repeated until 95% or more of f is reached. When the detected light amount value P further increases within a range of 95% or more of the light output reference value Pref and smaller than the light output reference value Pref, the output light amount error E becomes E ≦ Pref / 20, and
The magnitude of I3 is increased in the light amount control signal (p) (S70).
8). I3 takes a smaller value than I2, further improving the resolution of the first light quantity control signal (p). This sequence is repeated until the detected light amount value P becomes equal to or more than the light output reference value Pref. When the increased detected light amount value P reaches the light output reference value Pref (E = 0), the output light output reference value Po is reset. The light output reference value Pref is set (S71).
5) The first light quantity control signal value is latched by the buffer latch circuit 8 (S709), and the first light quantity control signal (p) output from the D / A converter 9 holds a constant value. Accordingly, the microprocessor 1 having obtained the desired laser light output is provided with the buffer latch circuit 27 and the D / A converter 28.
And outputs the optical output reference value Po for output via the buffer latch circuit 27 (S71).
7). Thereafter, the APC request signal (g) is turned off to turn off the laser (S710), and the integrator reset signal (v) is disabled to release the reset of the second light quantity control signal (t) (S718).

When the resolution of the laser beams I1 and I2 is insufficient due to variations in laser characteristics and the detected light amount P of the laser light output becomes larger than the light output reference value Pref, the output light amount error E becomes negative. Value (E <0). At this time, the first light quantity control signal (p) reduces the magnitude of I3 (S711), and reduces the laser light output. This sequence is repeated until the detected light amount value P is equal to or smaller than the light output reference Pref, that is, the output light amount error E becomes E ≧ 0 (S7).
11, S712, S713), the output light quantity error E is E ≧ 0.
At this point, the output light output reference value Po is set as the detected light amount value P at that time (S716), and the first light amount control signal value is latched by the buffer latch circuit 8 (S709).
The first light amount control signal (p) output from the D / A converter 9 is kept at a constant value. Accordingly, the microprocessor 1 having obtained a desired laser light output or a laser light output close to the desired value outputs the light output reference value Po for output via the buffer latch circuit 27 and the D / A converter 28, and The circuit 27 holds the value. Thereafter, the APC request signal (g) is turned off, the semiconductor laser 701 is turned off, and the integrator reset signal (v) is disabled to release the reset of the second light quantity control signal (t).

By the above operation, the temperature characteristics and the variation of the current-light output characteristics of the semiconductor laser 701 were corrected.
A first light amount control signal (s) for obtaining an optimum laser light output for image formation is set, and the microprocessor 1
The light output reference value Po of the light quantity control signal setting means is set, and the output of the second light quantity control signal (t) is permitted.

Next, in order to form an electrostatic latent image on the photosensitive member 19, an image signal (d) is input from the video controller 2 to the laser drive circuit 6 as a laser drive signal (j), and a third light amount control signal ( The laser operation current proportional to u) is supplied, and the semiconductor laser 701 performs pulse driving. As a result, the temperature of the laser oscillation region of the semiconductor laser 701 increases, and the laser light output decreases. At this time, the detected light amount signal (p) output from the detected light amount circuit 11 is subtracted from the light output reference value Po set by the microprocessor 1 by the subtracter 29, and converted into a value for controlling the laser operating current by the amplifier 30. Then, the output light amount error E2 of the semiconductor laser 701 is always obtained, and the decrease in the light output with respect to the laser light output optimum for image formation of the semiconductor laser 701 is quantitatively grasped. However, the output light amount error E2 output from the amplifier 30 has a very large value when the image signal (d) is OFF, which causes overcurrent destruction of the semiconductor laser 701 and hunting of the laser light output. The image signal (d) is changed to O by the sampling circuit 31.
By sampling the output light quantity error E2 in the case of N, only the output light quantity error when the laser is turned on is input to the integrator 33. The integrator 33 does not follow the high-frequency fluctuation of the output light quantity error, changes the optical output of the semiconductor laser 701 due to the transient thermal resistance and heat dissipation effect of the laser oscillation region, and does not cause an offset error. Therefore, the integrator performs charging and discharging with a constant time constant. Therefore, the second light quantity control signal (t) output from the integrator 33 is a signal for correcting the light quantity fluctuation of the laser light output turned on by the first light quantity control signal (s).

As described above, the first light quantity control signal (s)
The second light amount control signal (t) for correcting the laser light output fluctuation of the semiconductor laser that performs the pulse drive based on the image signal with the laser operation current proportional to is set. Therefore, the first light quantity control signal (s) and the second light quantity control signal (t) are added by the adder 34 to set the third light quantity control signal (u), and the laser operation current proportional to this signal is set. Since the laser beam is supplied to the semiconductor laser 701, real-time APC that can always obtain a uniform laser light output can be performed.

In the above description, the first light amount control means for controlling the laser operation current every time an image is formed on a recording material of one page is set. This may be performed at an arbitrary timing such as when e) is received.

<Embodiment 2> FIG. 3 shows the configuration of an apparatus according to a second embodiment. The same components as those in FIG. 5 are denoted by the same reference numerals. Regarding the configuration and operation, the same contents as those in the first embodiment are omitted, and the differences according to the present invention will be described below.

The laser drive circuit 6 includes a constant current circuit 601A for supplying a laser operation current proportional to the first light quantity control signal (s) and a constant current circuit 603A for supplying a laser operation current proportional to the second light quantity control signal. Constant current circuit 601
A, a switching circuit 602A for switching the laser operating current supplied from 603A.

In order to form an electrostatic latent image on the photosensitive member 19,
When an image signal (d) is input as a laser drive signal (j) from the video controller to the laser drive circuit 6, the laser drive circuit 6 causes the first and second light quantity control signals (s),
A plurality of constant current circuits 601A and 603A proportional to (t)
The laser operating current supplied from the switching circuit 60
Switching is performed at 2A based on the image signal (d), and the semiconductor laser 701 is pulse-driven. As a result, the temperature of the laser oscillation region of the semiconductor laser 701 increases, and the laser light output decreases. The second light quantity control signal (t) increases in order to correct the reduced laser light output, the laser operating current supplied by the constant current circuit 603A provided in the laser drive circuit 6 increases, and the uniform laser light Output can be held.

At this time, the laser drive current is increased in order to correct a decrease in the laser light output. As the operating current of the laser increases, the rise and fall time of the laser when the semiconductor laser 701 is pulse-driven by one constant current circuit increases. In the present embodiment, however, a plurality of constant current circuits 601A and 603A are used. Is used to prevent the rise and fall times from increasing.

Therefore, according to the present embodiment, real-time APC that can always obtain a uniform laser light output can be performed, and the rise and fall times of the laser can be kept constant.

<Embodiment 3> FIG. 4 is a block diagram of an apparatus according to a third embodiment, and the same components as those in FIG. 5 are denoted by the same reference numerals. Regarding the configuration and operation, the same contents as those in the first embodiment are omitted, and the differences will be mainly described below.

The laser drive circuit 6 includes a constant current circuit 601A for supplying a laser operation current proportional to the first light quantity control signal (s), and a switching circuit 60 for switching the laser operation current supplied from the constant current circuit 601A.
2B and a constant current circuit 603B for supplying a laser bias current (k2) proportional to the second light quantity control signal (t).

In order to form an electrostatic latent image on the photosensitive member 19,
When the image signal (d) is input from the video controller 2 to the laser drive circuit 6 as a laser drive signal (j), the laser drive circuit 6 supplies the laser light supplied from the constant current circuit 601A in proportion to the first light quantity control signal (s). By switching the operating current by the switching circuit 602B, a laser drive current (k) is supplied to the semiconductor laser 701, and the semiconductor laser 701 is pulse-driven. As a result, the temperature of the laser oscillation region of the semiconductor laser 701 increases, and the laser light output decreases. The second light quantity control signal (t) increases in order to correct the reduced laser light output, and the laser bias current (k2) supplied by the constant current circuit 603B provided in the laser drive circuit 6 increases, thereby increasing the uniformity. Laser light output can be maintained.

At this time, the laser bias current (k2) is increased in order to correct a decrease in the laser light output. Although the laser rise / fall time when the semiconductor laser 701 is pulse-driven by one constant current circuit as described in the first embodiment becomes longer, in this embodiment, the laser bias current (k2) is supplied because the laser bias current (k2) is supplied. The rise and fall times do not change. Further, since the laser bias current (k2) for correcting the laser light output fluctuation caused by the temperature rise in the laser oscillation region is a very small value, it does not exceed the threshold current of the semiconductor laser 701 and is unnecessary. It does not cause excessive laser lighting.

Therefore, according to the present embodiment, real-time APC that can always obtain a uniform laser light output can be performed, and the rise and fall times of the laser can be kept constant.

As described above, according to the embodiment of the present invention, the following effects can be obtained. (1) Laser light output adjustment during image formation can be performed, and laser light output optimal for image formation can always be maintained.

(2) The occurrence of density unevenness can be prevented, and the quality of an image can be prevented from deteriorating.

(3) A tone reproduction characteristic with high linearity is obtained, and high-quality halftone expression can be performed.

(4) The standard value of the droop characteristic of the semiconductor laser can be reduced, and the cost can be reduced by improving the yield of the semiconductor laser.

[0058]

As described above, according to the present invention,
Fluctuations in optical output due to droop characteristics of the laser can be compensated with high resolution.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus according to a first embodiment.

FIG. 2 is a flowchart of laser light output adjustment according to the first embodiment.

FIG. 3 is a configuration diagram of an apparatus according to a second embodiment.

FIG. 4 is a configuration diagram of an apparatus according to a third embodiment.

FIG. 5 is a configuration diagram of a conventional device.

FIG. 6 is a flowchart illustrating an image forming process of a conventional apparatus.

FIG. 7 is a flowchart of laser light output adjustment of the conventional device.

FIG. 8 is a diagram showing a relationship between a laser operating current and a laser light output.

FIG. 9 is a diagram showing a droop characteristic of a laser.

FIG. 10 is a diagram illustrating the relationship between laser light output and image density.

FIG. 11 is a diagram illustrating a relationship between a pulse width and an image density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microprocessor 2 Video controller 3 Horizontal synchronization request circuit 4 OR circuit 5 OR circuit 6 Laser drive circuit 601 Constant current circuit 602 Switching circuit 603 Constant current circuit 7 Scanner unit 701 Semiconductor laser 702 Collimator lens 703 Cylindrical lens 704 Polygon mirror 705 Motor 706 Toric lens 707 fθ lens 708 Motor drive circuit 8 Buffer latch circuit 9 D / A converter 10 A / D converter 11 Light quantity detection circuit 12 Recording material conveyance detection circuit 13 Horizontal synchronization detection circuit 14 Primary charger 15 Light receiving element 16 Developing device 1601 Development Cylinder 17 Transfer charger 18 Cleaner 20 Cassette 21 Pickup roller 22 Feed roller 23 Recording material detecting element 24 Registration roller 25 Fixer 6 discharge roller 27 buffer latch circuit 28 D / A converter 29 the subtracter 30 the amplifier 31 sampling circuit 32 timing generating circuit 3201 the AND circuit 3202 the delay circuit 33 integrator 34 adder

Claims (5)

(57) [Claims] 1. An image forming apparatus for irradiating a photoreceptor with a laser to form an electrostatic latent image, comprising: detecting means for detecting a light output of the laser; and causing the light output of the laser to be a reference value. A first control means for outputting a first light quantity control signal for instructing a laser operation current; and a first light quantity control based on an error between a detection value output from the light quantity detection means and the reference value. A second control unit that outputs a second light amount control signal representing a laser operation current to be added to the laser operation current by the signal; a laser operation current represented by the first light amount control signal; and the second light amount control signal Supply means for supplying a laser operation current indicating addition of the laser current to the laser to the laser, and the second light amount during a period in which the first control means variably controls the level of the first light amount control signal. Reset control signal An image forming apparatus characterized in that comprises a reset means. 2. An adding means for adding the first light quantity control signal and the second light quantity control signal; and an operating current of the laser in proportion to the third light quantity control signal output from the adding means. The image forming apparatus according to claim 1, further comprising a constant current circuit for supplying. 3. A first constant current circuit for supplying a laser operation current in proportion to the first light quantity control signal, and a second constant current circuit for supplying a laser operation current in proportion to the second light quantity control signal. The image forming apparatus according to claim 1, further comprising a constant current circuit. 4. The image forming apparatus according to claim 3, further comprising switching means for switching a laser operation current supplied by said first constant current circuit according to a laser drive signal. 5. The apparatus according to claim 1, wherein the second control means variably controls a laser current supplied to the laser in accordance with the second light quantity control signal during a period in which the laser emits a pulse based on an image signal. The image forming apparatus according to claim 1.