JPH1178108A - Light amount switching determination method and image forming apparatus - Google Patents

Abstract

(57) Abstract: In an image forming apparatus using a laser, it is determined whether switching of a laser light amount of a laser driving unit and switching of a detection level of a light detecting unit are normally performed. A control unit sets a light amount to be adjusted by a laser drive unit and a detection level of a light detection unit to a high light amount, and after confirming that the light detection unit outputs a detection signal, adjusts the laser drive unit. When the light detection means does not output the detection signal when only the light amount to be changed to the low light amount, it is determined that the laser driving means can be controlled normally, and when the light detection means outputs the detection signal,
It is determined that the laser drive means cannot be controlled normally. The determination of the switching of the detection level of the light detection means
The same operation is performed by switching the detection level of the light detecting means while keeping the laser light amount low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining light amount switching in an image forming apparatus used in an electrophotographic printer or copier.

[0002]

2. Description of the Related Art Conventionally, this type of image forming apparatus has a conceptual configuration as shown in FIG.

In the image forming apparatus main body, reference numeral 100 denotes a process cartridge that can be attached to and detached from the image forming apparatus main body. A photosensitive drum 102 for forming an electrostatic latent image inside the process cartridge 100;
And a developing device 110 for developing an electrostatic latent image formed on the photosensitive drum 102 by a laser beam with toner. Reference numeral 101 denotes a scanner unit, which is provided for scanning the photosensitive drum 102 with a laser beam. A transfer roller charger 103 transfers a toner image formed on the photosensitive drum 102 to a predetermined sheet.
Is a fixing unit that melts the toner image on the paper and fixes it on the paper, 106 is a discharge roller that discharges the paper on which the toner image is fixed outside the machine, and 105 is a discharge that detects that the paper has passed through the fixing unit 104. Sensor 107, a registration sensor for detecting the leading edge of the sheet; 109, a cassette in which the sheet size on which sheets are to be loaded is known in advance;
Reference numeral 9 denotes a paper feed roller for feeding paper to the photosensitive drum 102 side.

Next, the scanner unit 101 will be described.

FIG. 5 is a conceptual diagram showing the internal configuration of the scanner unit 101. 201 is O according to the image signal.
N / OFF semiconductor laser; 202, a laser driver for driving semiconductor laser 201 in response to laser drive signal 151 modulated by an image signal from engine control unit 209; 204, laser light emitted from semiconductor laser 201; A collimator lens for making the diffused radiation parallel light, a cylindrical lens 205 for compressing the parallelized laser light only in the vertical direction, and a rotating polygon mirror 207 for reflecting and deflecting and scanning the laser light passing through the cylindrical lens 205 (Polygon mirror), 203 is a scanner motor for rotating a rotary polygon mirror (polygon mirror) 207, 206 is a scanner motor driver for driving the scanner motor 203 based on a drive signal from an engine control unit 209, and 208 is a rotary polygon mirror The laser beam reflected by the mirror 207 is A toric lens for converting the laser beam scanning on the ram 102 at a constant speed, an image forming lens 111 for correcting the optical path length of the rotating polygon mirror and the photosensitive drum, and a scanning lens 210 which is deflected and scanned by the rotating polygon mirror and horizontally. The laser beam reflected on the synchronization mirror 213 is received, and a horizontal synchronization signal ("/ BD" signal ("/" represents negative logic)) for determining a writing start position for each main scanning line at the time of receiving the laser beam is received. A light receiving element (hereinafter referred to as a BD sensor) provided at a predetermined position outside the effective image area to be output, and 212 is a reflection mirror for reflecting the laser light passing through the imaging lens 111 and irradiating the photosensitive drum 102 with the laser light It is.

[0006] The BD sensor 210 has a threshold value and outputs an output when a certain amount or more of light enters. However, the threshold value can be set by an external instruction.

Next, scanner control performed by the engine control unit 209 will be described.

FIG. 1 shows a scanner unit 101 (FIG. 4).
The operation of the scanner unit will be described with reference to a timing chart shown in FIG.

When the engine control unit 209 receives a print signal "/ PRNT" (not shown) from a printer controller (not shown), it sends a scanner acceleration signal "/ SCNADD" to the scanner motor driver 206 to TRUE.
In the state, the scanner deceleration signal “/ SCNDEC” is FAL
In the SE state, the scanner motor 203 is rotated (time T601). After about 500 msec has elapsed from the start of rotation, the laser forcible lighting signal “/ LON” is set to the TRUE state (time T602). If the deflection-scanned laser beam irradiates the light receiving element 210 to obtain the horizontal synchronization signal "/ BD", the "/ LON" signal is set to FALSE (time T603), and then the "/ deflection-scanned laser beam. Illuminates the light receiving element 210 and obtains the “/ BD” signal a short time before the “/ LON” signal is output to the TR again.
The control for the UE (time T604) is repeatedly performed (time T605). By doing so, the scanner motor 20
The number of rotations of 3 gradually increases, and when the period of the "/ BD" signal falls within a predetermined range (time T606), it is determined that the scanner is ready.

In the state of the scanner ready, "/ S
"CNADD" and "/ SCNDEC" are controlled to DUTY so as to keep the rotation speed of the scanner motor in a steady state.
In order to determine the print area in the main scanning direction, after a certain period (time T60) after receiving the "/ BD" signal (time T607).
8) Set the enable signal “/ ENBL” to TRUE,
After the scanning time for the print area has elapsed (time T609), FAL
Set to SE. On the other hand, the printer controller drives the laser drive signal "/ VDATA" modulated by the image signal after a fixed time (time T608) after receiving the "/ BD" signal from the engine control unit.

By performing the above operations, the photosensitive drum 1
02, an electrostatic latent image is formed.

When switching the resolution, it is necessary to change the laser light amount. At this time, the laser light amount switching signal "PCCHANGE" is changed, and the laser light amount value is switched and the image is formed. Also, with the switching of the laser light amount, the BD sensor is set to “/ B
The signal "CHSLVL" for setting the amount of incident light necessary to output the D "signal is also switched in accordance with the amount of laser light. For example, when switching between two resolutions, a high light amount and a low light amount are switched. What is necessary is just to set two types of laser light amounts and the threshold value of the BD sensor, and the “PCCHANGE” signal and the “CHSLVL” signal are 1-bit signals.

[0013]

However, in the above-mentioned conventional example, it is not possible to determine that the laser light amount switching is normally performed when the laser light amount needs to be switched, for example, when the resolution is switched. .
For this reason, even when high-resolution printing is designated, printing with high light quantity corresponding to low resolution may be performed.

Further, in the above conventional example, whether the incident light amount necessary for the BD sensor to output the "/ BD" signal is switched in accordance with the light amount of the laser,
Since it was not possible to determine whether the detection level (threshold) of the sensor was switched, the image writing position in the main scanning direction was shifted.

Accordingly, an object of the present invention is to determine whether the switching of the laser light amount and the switching of the detection level of the BD sensor are performed normally.

[0016]

According to the present invention, there is provided a light amount switching determination method, comprising the steps of: driving a semiconductor laser that emits a laser beam; and driving the semiconductor laser based on a signal that is PWM-modulated with an image signal. Adjustable laser driving means, a rotating polyhedron for deflecting and scanning the laser beam to form a scanning line, a photosensitive drum for forming an image on a portion irradiated with the scanning line, and a rotation for rotating the rotating polyhedron A driving unit, a light detection unit provided at a start end on the scanning line, detecting the laser beam and outputting a detection signal, and capable of setting a detection level; a light amount adjusted by the laser driving unit; And a control means for generating a signal PWM-modulated with the image signal and supplying the signal to the laser driving means. In the determination method, the control unit sets the light amount adjusted by the laser driving unit and the detection level of the light detection unit to a high light amount, and after confirming that the light detection unit outputs the detection signal, ,
When only the light amount adjusted by the laser driving unit is switched to a low light amount and the light detection unit does not output the detection signal, it is determined that the light amount adjusted by the laser driving unit can be normally switched, and the light detection is performed. When the means outputs the detection signal, it is determined that the light amount adjusted by the laser driving means cannot be normally switched.

An image forming apparatus according to the present invention is characterized by using the above-described light amount switching determination method.

In the image forming apparatus according to the present invention, in the above-described image forming apparatus, when the control unit determines that the light amount to be adjusted by the laser driving unit cannot be normally switched, the control unit requests the setting of a low light amount. Also, when the light amount adjusted by the laser driving means and the detection level of the light detecting means are set to a high light amount, the modulation degree of the PWM modulation is reduced to generate a signal corresponding to the low light amount, and an image is generated. It is characterized by forming.

According to the present invention, there is provided a method for determining light amount switching, comprising: a semiconductor laser for emitting laser light; and laser driving means for driving the semiconductor laser based on a signal modulated by an image signal and capable of adjusting the light amount of the laser light. A rotating polyhedron that deflects and scans the laser light to form a scanning line; a photosensitive drum that forms an image on a portion irradiated with the scanning line; a rotation driving unit that rotates the rotating polyhedron; Provided at the beginning of the laser light, detects the laser beam and outputs a detection signal, and a light detection unit capable of setting a detection level;
An image forming apparatus comprising: a control unit that sets a light amount to be adjusted by the laser driving unit and a detection level of the light detection unit, generates a signal that is PWM-modulated by the image signal, and supplies the signal to the laser driving unit. In the light amount switching determination method of the apparatus, the control unit sets the light amount adjusted by the laser driving unit and the detection level of the light detection unit to a low light amount, and confirms that the light detection unit outputs the detection signal. Then, when only the detection level of the light detection unit is switched to a high light amount, when the light detection unit does not output the detection signal, it is determined that the detection level of the light detection unit can be normally switched, When the light detection means outputs the detection signal, it is determined that the detection level of the light detection means cannot be normally switched. .

An image forming apparatus according to the present invention is characterized by using the above-described light amount switching determination method.

According to a second aspect of the present invention, there is provided a method for determining the amount of light of a laser beam, the method comprising: driving a semiconductor laser based on a signal modulated by an image signal; Means, a rotating polyhedron for deflecting and scanning the laser light to form a scanning line,
A photosensitive drum that forms an image on a portion irradiated with the scanning line, and a rotation driving unit that rotates the rotating polyhedron,
It is provided at the start end on the scanning line, detects the laser beam, outputs a detection signal, and sets a light detection unit capable of setting a detection level, a light amount to be adjusted by the laser driving unit, and a detection level of the light detection unit. Control means for generating a signal PWM-modulated with the image signal and supplying the signal to the laser drive means, wherein the control means adjusts the laser drive means. Whether the light amount of the laser driving unit and the detection level of the photodetector are normally switched based on the presence / absence of the detection signal and the actual presence / absence expected for each combination of the light amount to be detected and the detection level of the light detection unit. Is determined.

An image forming apparatus according to the present invention is characterized by using the above-described light amount switching determination method.

In the image forming apparatus according to the present invention, when it is determined in the above image forming apparatus that the light amount adjusted by the laser driving means or the detection level of the light detecting means cannot be normally switched, the control is performed. Even when the setting of the light amount that cannot be selected by the unit is requested, the light amount adjusted by the laser driving unit and the detection level of the light detection unit are set to the selectable light amount, and the parameters of the PWM modulation are adjusted and selected. An image is formed by generating a signal corresponding to the amount of light that cannot be obtained.

[0024]

FIG. 4 shows a conceptual configuration of an image forming apparatus according to an embodiment of the present invention. Since this description has already been made, duplicate description will be omitted. FIG. 5 shows the scanner unit 101 shown in FIG. Since this description has already been made, a duplicate description will be omitted.

[Embodiment 1] FIG. 1 shows Embodiment 1 of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a scanner unit according to the first embodiment. Since this description has already been made, a duplicate description will be omitted.

FIG. 2 is a timing chart relating to the determination of the switching of the laser light amount at the time of starting the scanner, which is performed by the engine control unit 209 (FIG. 1) in this embodiment. I do. In the conventional example, the signal “CHSLVL” and the signal “PCHANGE” are switched in conjunction with each other. However, in the present embodiment, the signal “CHSLVL” and the signal “CHANGL”
PCCHANGE "is switched independently.

In the configuration of the scanner unit shown in FIG. 1, when the engine control unit 209 receives a print signal "/ PRNT" from a printer controller (not shown), a scanner acceleration signal "/ SC" for the scanner motor driver 206 is received.
NADD "is set to the TRUE state, and the scanner deceleration signal" / S
CNDEC ”is set to the FALSE state, and the scanner motor 2
03 is activated (time T201). At this time, "PC
The "HANGE" signal is set to LOW (high light quantity), and the "CHSLVL" signal is set to HIGH (high light quantity side).

When, for example, several msec has elapsed from the start of rotation, the laser forcible lighting signal "/ LON" is set to the TRUE state (time T202). When the / horizontal synchronization signal "/ BD" is obtained, the "/ LON" signal is set to FALSE, and the "PCHANGE" signal is set to HIGH (low light quantity) (time T203). This makes it possible to switch the laser light quantity at the time of the next laser forcible lighting to a low light quantity. Also, the laser light amount after switching is
The incident light amount required for the BD sensor 210 to output the “/ BD” signal is set lower. Next, "/ B
D ”from a time before the signal would be obtained again.
/ LON ”signal to the TRUE state (time T20
4). "/ B"
If the D ″ signal cannot be obtained, it can be determined that the laser light amount switching has been normally performed.

When the engine control unit determines that the laser light amount can be switched normally, the engine control unit sets the laser light amount to the light amount for printing (time T205, in the example of this embodiment, the light amount is set to the high light amount side). ), And then perform scanner control and printing.

As described above, the amount of incident light necessary for the BD sensor to output the "/ BD" signal at the start of driving the scanner is set to a value corresponding to the amount of laser light on the high light amount side, and the amount of laser light becomes high. The "/ BD" signal is detected when the "PCHANGE" signal is set as described above, and it is determined whether the "/ BD" signal is not detected when the "PCHANGE" signal is switched so that the laser light amount becomes low. This makes it possible to determine whether or not it is possible to normally switch the laser light amount by switching the “PCCHANGE” signal.

[Embodiment 2] FIG. 3 shows Embodiment 2 of the present invention.
4 is a timing chart of the laser light amount switching determination performed by the engine control unit 209, and the present embodiment will be described below with reference to FIG.

When activating the scanner, the engine control unit 209 outputs a laser light amount switching signal “PCHANG”.
E ”signal on the low light intensity side (HIGH),
The signal “CHSLVL” signal for setting the amount of incident light necessary to output the “BD” signal is also on the low light amount side (HIG
H) (time 301). When the laser forcible lighting is performed in this state (time T302), a "/ BD" signal is output (time T303).

Next, the "CHSLVL" signal is switched to the high light quantity side (LOW) (time T304). If the "/ BD" signal cannot be obtained at the next laser forcible lighting (time T305), the BD sensor 210 responds to the light amount.
/ BD "sensor required to output a" BD "signal 210
It can be determined that the normal switching of the incident light amount setting has been performed.

If it is determined that normal switching can be performed, the setting of the laser light amount and the incident light amount necessary for the BD sensor to output the "/ BD" signal is set to the light amount for actually printing. (At time T306, in the example of this embodiment, it is set to the low light amount side), scanner control and printing are performed.

As described above, the laser light amount is set to the low light amount side at the start of the scanner driving, and the "CHSLVL" signal is set to the HI level.
When the incident light amount setting required for the BD sensor 210 to output the “/ BD” signal by setting it to GH is set to the low light amount side, the BD sensor 210 detects the “/ BD” signal and outputs “CH”.
SLVL "signal is set to LOW and the BD sensor 210
Determines whether or not the "/ BD" signal is not detected when the incident light amount setting required to output the "/ BD" signal is set to the high light amount side, and the BD sensor is switched by switching the "CHSLVL" signal. It is possible to determine that the switching of the incident light amount setting necessary for the 210 to output the “/ BD” signal is performed normally.

[Third Embodiment] In the first and second embodiments, the success / failure of the laser light amount switching and the BD sensor are set to "/ BD".
The method for judging the success or failure of the switching of the amount of incident light necessary for outputting a signal has been described.

In the present embodiment, a process in the case where an abnormality is detected in the switching will be described. The existence of the "/ BD" signal is indispensable for controlling the scanner motor speed. Therefore, in order to continuously control the rotation speed of the scanner motor, a combination of the amount of laser light that can secure the "/ BD" signal and the amount of incident light necessary for the BD sensor to output the "/ BD" signal is required. Becomes

For example, in the first embodiment, "PCHANG"
E "Even after switching the signal from the high light intensity side to the low light intensity side,
When the / BD "signal is obtained, the engine control unit 209 determines that there is an abnormality in the switching of the laser light amount. In this case, it can be determined that the laser light amount can be set only on the high light amount side. BD sensor 210 is
The amount of incident light necessary to output the / BD "signal is set on the high light amount side. In this way, printing with the high light amount specified can be performed normally. Printing on the low light amount side cannot be performed. It may be transmitted to a controller (not shown), or when a low light quantity print is requested, "/ V
By narrowing the ON DUTY of the "DATA" signal to the low light amount side and performing printing, it is possible to perform printing equivalent to low light amount printing by high light amount printing. The "/ VDATA" signal is determined by the image signal. PW
This is an M-modulated signal. Therefore, "/ VDAT
Reducing ON DUTY of the A ″ signal to the low light amount side corresponds to reducing the modulation degree of PWM modulation.

In the second embodiment, the BD sensor 210 is set to "/ B
If the “/ BD” signal can be obtained even after the switching of the amount of incident light necessary to output the “D” signal, the engine control unit 209 causes the BD sensor 210 based on the “CHSLVL” signal to output the “/ BD” signal. It is determined that there is an abnormality in the switching of the amount of incident light necessary to output.

At this time, the BD sensor 210 outputs "/ B
It can be determined that the switching of the amount of incident light necessary to output the D ″ signal can be set only on the low light amount side.
Set the laser light amount to the low light amount side. By doing so, printing in which low light intensity is specified can be performed normally.
The print on the high light amount side may be notified to the printer controller (not shown) that it is out of order, or may be displayed on a panel.

In the first and second embodiments described above, the success or failure of the laser light amount switching and the success or failure of the incident light amount switching required for the BD sensor to output the "/ BD" signal are determined independently. First, the determination of the success or failure of the switching of the laser light amount, and second, the BD sensor detects "/ BD".
It goes without saying that the determination of the success or failure of the switching of the amount of incident light necessary to output the signal may be performed.

Although the description has been made assuming that the light amount is of two types, that is, a high light amount and a low light amount, even when the light amount is three or more, the same judgment and the switching of the print according to the judgment result are performed. can do.

As described above, even when it is determined that there is an abnormality in the switching of the amount of laser light emitted from the semiconductor laser or the amount of incident light (threshold) for outputting the "/ BD" signal of the BD sensor, an operation corresponding to the abnormality is performed. By doing so, printing can be continuously performed.

[0044]

As described above, according to the present invention,
The following effects can be expected.

The scanner is activated when the switching of the laser light amount is performed normally and the switching of the specified incident light amount required for the BD sensor to output the horizontal synchronizing signal ("/ BD" signal) is normally performed. Sometimes the engine control can self-diagnose.

Even when an abnormality is detected in the switching control, by using the settable laser light amount and adjusting the laser drive signal, a print equivalent to the required laser light amount can be obtained. It is possible to continue.

[Brief description of the drawings]

FIG. 1 is a block diagram of a scanner unit according to the present invention and a conventional example.

FIG. 2 is a timing chart of internal signals of the scanner unit when laser light amount switching is determined according to the first embodiment of the present invention.

FIG. 3 is a timing chart of internal signals of a scanner unit when laser light amount switching is determined according to a second embodiment of the present invention.

FIG. 4 is a conceptual configuration diagram of an image forming apparatus according to the present invention and a conventional example.

FIG. 5 is a conceptual diagram showing an internal configuration of a scanner unit according to the present invention and a conventional example.

FIG. 6 is a timing chart of signals inside a scanner unit in a conventional example.

[Explanation of symbols]

 Reference Signs List 101 scanner unit 201 semiconductor laser 202 laser driver 206 scanner motor driver 209 engine control unit 210 light receiving element 210 BD sensor

Claims (8)

[Claims] 1. A semiconductor laser that emits a laser beam, a laser driving unit that drives the semiconductor laser based on a signal that is PWM-modulated with an image signal and that can adjust a light amount of the laser beam, and deflects the laser beam. A rotating polyhedron that scans to form a scanning line; a photosensitive drum that forms an image on a portion irradiated with the scanning line; a rotation driving unit that rotates the rotating polyhedron; Detecting the laser beam, outputting a detection signal, and setting a light level that can be set to a detection level; a light amount to be adjusted by the laser driving unit; and a detection level of the light detection unit. Control means for generating a modulated signal and supplying the modulated signal to the laser driving means. After setting the amount of light to be adjusted by the laser driving means and the detection level of the light detecting means to be high, and confirming that the light detecting means outputs the detection signal, only the amount of light to be adjusted by the laser driving means When the light detection means does not output the detection signal,
It is determined that the light amount to be adjusted by the laser driving unit can be normally switched, and when the light detection unit outputs the detection signal, it is determined that the light amount to be adjusted by the laser driving unit cannot be normally switched. Light amount switching determination method. 2. An image forming apparatus using the light amount switching determination method according to claim 1. 3. The image forming apparatus according to claim 2, wherein when it is determined that the light amount to be adjusted by the laser driving unit cannot be normally switched, the control unit is requested to set a low light amount. It is also preferable that the light amount adjusted by the laser driving means and the detection level of the light detecting means are set to a high light amount, and the modulation degree of the PWM modulation is reduced to generate a signal corresponding to the low light amount to form an image. Characteristic image forming apparatus. 4. A semiconductor laser that emits a laser beam, a laser driving unit that drives the semiconductor laser based on a signal modulated by an image signal and that can adjust a light amount of the laser beam, and deflects and scans the laser beam. A rotating polyhedron for forming a scanning line; a photosensitive drum for forming an image on a portion irradiated with the scanning line; a rotation driving unit for rotating the rotating polyhedron; Detecting a laser beam and outputting a detection signal, setting a detection level of a light detection unit, a light amount to be adjusted by the laser driving unit, and a detection level of the light detection unit, and performing PWM modulation with the image signal Control means for generating a signal obtained and supplying the signal to the laser driving means, the control means comprising: The light quantity to be adjusted by the driving means and the detection level of the light detection means are set to low light quantity, and after confirming that the light detection means outputs the detection signal, only the detection level of the light detection means is increased. When switching to the light amount, when the light detection means does not output the detection signal,
It is determined that the detection level of the light detection means can be normally switched, and that the detection level of the light detection means cannot be normally switched when the light detection means outputs the detection signal. Light intensity switching determination method. 5. An image forming apparatus using the light amount switching determination method according to claim 4. 6. A semiconductor laser that emits a laser beam, a laser driving unit that drives the semiconductor laser based on a signal modulated by an image signal and that can adjust a light amount of the laser beam, and deflects and scans the laser beam. A rotating polyhedron for forming a scanning line; a photosensitive drum for forming an image on a portion irradiated with the scanning line; a rotation driving unit for rotating the rotating polyhedron; Detecting a laser beam and outputting a detection signal, setting a detection level of a light detection unit, a light amount to be adjusted by the laser driving unit, and a detection level of the light detection unit, and performing PWM modulation with the image signal Control means for generating a signal obtained and supplying the signal to the laser driving means, wherein the control means comprises: The light amount of the laser driving unit and the detection level of the photodetector are normally determined from the presence / absence and actual presence / absence of the detection signal expected for each combination of the light amount adjusted by the driving unit and the detection level of the light detection unit. A light amount switching determination method characterized by determining whether to switch. 7. An image forming apparatus using the light amount switching determination method according to claim 6. 8. The image forming apparatus according to claim 7, wherein when it is determined that the light amount adjusted by the laser driving unit or the detection level of the light detecting unit cannot be normally switched, the control unit cannot be selected. Even when the setting of the light amount is requested, the light amount adjusted by the laser driving unit and the detection level of the light detection unit are set to selectable light amounts, and the PWM modulation parameters are adjusted to correspond to the light amounts that cannot be selected. An image forming apparatus, which generates a signal to generate an image.