JP2001293903A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus in which a laser light source comprising a plurality of light emitting elements arranged in array can be prevented from deteriorating by performing detection of synchronization or adjustment of the intensity of light while lighting only specified light emitting elements and unlighting other light emitting elements. SOLUTION: When a digital copy machine performs recording of an image by a printer section 14 based on image information of a document read out by a scanner section 13 or image information inputted externally, a control section 8 performs detection of synchronization and APC control processing. The APC operation processing is performed, as required, during image formation because the optical output from an LD array 6 is required to be stabilized. At the time of waiting, the control section 8 performs APC operation only for a specified channel in order to ensure a synchronization signal and interrupts output of an APC operation signal for other channels to stop lighting of the light emitting elements of these channels. Consequently, the lifetime of the LD array 6 can be prolonged while reducing the running cost.

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, and more particularly, to an image forming apparatus in which a plurality of light emitting elements are arranged in an array to prevent deterioration of a laser light source and extend the life of the laser light source. Related to the device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a digital copying machine, a digital printer and a digital facsimile machine, a laser beam emitted from a laser light source such as a semiconductor laser or the like can record a high-quality image at a high speed. 2. Description of the Related Art Electrophotographic image forming apparatuses that form an image using light have become widespread.

In order to respond to the demand for higher speed, such an image forming apparatus has conventionally been provided with a multi-beam laser to increase the speed due to restrictions on the number of rotations of a polygon motor.

As one of such multi-beam methods, a method of simultaneously writing a plurality of lines of image data on a photosensitive drum using an LD (Laser Diode) array has been used.

However, when an LD array is used, the LD
If one of the plurality of light emitting elements (LD) in the array cannot operate normally due to deterioration or the like, it is necessary to replace the LD array itself even if other light emitting elements can be used. Arrays are expensive and have the problem of high running costs.

As a method of determining the deterioration of a light emitting element such as an LD, for example, in a copying machine, the amount of current required to output a certain amount of light is monitored as needed, and the amount of current is set in advance. If the current value exceeds the reference current value, it is determined that the light emitting element has deteriorated. In addition, factors of the deterioration of the light emitting element include an inrush current generated when image data is turned on or the like, and a temporal deterioration caused by a total lighting time of the light emitting element.

Therefore, the present applicant first drives the light source with the modulation signal for synchronizing detection and the information signal to deflect the light beam from the light source by the scanning device, and shifts the light beam from the scanning device to a predetermined position. In the image forming apparatus which generates the information signal in synchronization with the synchronization detection signal by detecting with the synchronization detector, the light source is turned on in response to the end of the counting of the predetermined number of clock pulses. A counter that generates the synchronization detection modulation signal for emitting light, a gate circuit that receives the synchronization detection signal and the synchronization detection modulation signal as inputs, and generates an output signal only when the two signals are generated; Wherein the counter starts counting and stops generating the synchronization detection modulation signal in response to generation of an output signal from the gate circuit. Proposes an image forming apparatus (see Japanese Patent Laid-Open No. 7-234368).

That is, in this image forming apparatus, the lighting time is shortened by shortening the output timing of the synchronization detection signal, and the life of the LD as the light source is extended.

[0009]

However, in the prior art described in the above-mentioned publication, the lighting time is shortened and the life of the LD which is the light source is extended by shortening the output timing of the synchronization detection signal. Therefore, there is a need for improvement in extending the life of an expensive LD array.

That is, the deterioration of the LD array is often caused by the total lighting time, and it is not sufficient to shorten the lighting time by shortening the synchronization detection signal output timing, and further reduce the lighting time. Therefore, it is necessary to extend the life of the LD array. It is also necessary to consider that the rush current generated when the image data is turned on also causes the LD array to deteriorate.

Therefore, the invention according to claim 1 provides a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array. A laser light source is used for forming an image while irradiating the synchronization detection means arranged at a position deviating from the latent image forming area in the main scanning direction and performing alignment in the main scanning direction based on the detection result of the synchronization detection means. By turning off the light-emitting elements other than the light-emitting element that emits a laser beam that irradiates the synchronization detection means among the plurality of light-emitting elements,
An object of the present invention is to provide an image forming apparatus capable of stopping operation of unnecessary light emitting elements, extending the life of an expensive laser light source including a light emitting element array such as an LD array, and reducing running costs. I have.

According to a second aspect of the present invention, a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array forms a main scan of a latent image carrier. Irradiates the synchronization detection means and the light intensity detection means arranged at positions deviated from the latent image forming area in the direction, performs position adjustment in the main scanning direction based on the detection result of the synchronization detection means, and performs the light intensity detection. While adjusting the light intensity of each light emitting element based on the detection result of the means, when forming an image, the light intensity adjustment of the light emitting elements other than the light emitting element that emits the laser beam for irradiating the synchronization detecting means among the plurality of light emitting elements By stopping the operation, the light emission intensity of the light emitting elements other than the light emitting element to be turned on for synchronization detection, that is, the current supplied to the light emitting element by reducing the light emission intensity of the light emitting element unnecessary for operation Lowered, and extends the life of expensive laser light source comprising a light emitting element array such as a LD array, and its object is to provide an image forming apparatus capable of reducing the running cost.

According to a third aspect of the present invention, a light emitting element other than a light emitting element that emits a laser beam for irradiating the synchronization detecting means is turned off or the light intensity adjusting operation is stopped in a standby state, so that the synchronization signal is output during the standby state. Stopping light emission of light emitting elements not involved in the securing operation, preventing unnecessary light emission of unnecessary light emitting elements, further extending the life of expensive laser light sources including light emitting element arrays such as LD arrays, and running costs It is an object of the present invention to provide an image forming apparatus capable of further reducing image quality.

According to a fourth aspect of the present invention, the amount of current supplied to each light emitting element of the laser light source is detected by current detecting means.
The light emitting element having the smallest current amount among the detected current amounts to the respective light emitting elements is selected by the selecting means, and a laser beam to be emitted to the synchronization detecting means or the light intensity detecting means among the plurality of light emitting elements of the laser light source is emitted. By using a light emitting element having the smallest amount of current selected by the selecting means as the light emitting element to perform, the bias of deterioration among a plurality of light emitting elements of the laser light source is prevented, and an expensive laser comprising a light emitting element array such as an LD array is used. It is an object of the present invention to provide an image forming apparatus that can further extend the life of a light source and further reduce running costs.

[0015]

According to a first aspect of the present invention, there is provided an image forming apparatus, wherein a plurality of light emitting elements are emitted from a predetermined light emitting element among the plurality of light emitting elements of a laser light source arranged in an array. Irradiates the laser beam to the synchronization detecting means arranged at a position deviating from the latent image forming area in the main scanning direction of the latent image carrier, and performs alignment in the main scanning direction based on the detection result of the synchronization detecting means. While irradiating the latent image carrier with a laser beam modulated based on image information from the laser light source in the main scanning direction to form an electrostatic latent image on the latent image carrier, An image forming apparatus that forms a developer image by applying and developing a developer to the formed latent image carrier to form a developer image and transferring the developer image on the latent image carrier to transfer paper to form an image. The front of the plurality of light emitting elements of the laser light source By a control means for turning off the light-emitting element other than the light emitting element for emitting a laser beam to be irradiated to the synchronization detection means, it has achieved the above objects.

According to the above configuration, a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array is arranged in the main scanning direction of the latent image carrier. A plurality of laser light sources emit light when forming an image while irradiating the synchronization detection means arranged at a position outside the latent image formation area and performing alignment in the main scanning direction based on the detection result of the synchronization detection means. Since the light emitting elements other than the light emitting element that emits the laser beam that irradiates the synchronization detecting means among the elements are turned off, unnecessary lighting of the light emitting elements that are unnecessary for operation is stopped, and an expensive light emitting element array such as an LD array is formed. The life of the laser light source can be extended,
Running costs can be reduced.

According to a second aspect of the present invention, there is provided an image forming apparatus, comprising: a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array; Irradiates the synchronization detecting means and the light intensity detecting means arranged at a position deviating from the latent image forming area in the main scanning direction of the carrier, and performs positioning in the main scanning direction based on a detection result of the synchronization detecting means. Irradiating the latent image carrier with a laser beam modulated based on image information from the laser light source in the main scanning direction while adjusting the light intensity of each of the light emitting elements based on the detection result of the light intensity detection means. Forming an electrostatic latent image on the latent image carrier, applying a developer to the latent image carrier on which the electrostatic latent image is formed, and developing the latent image carrier to form a developer image; Transfer developer image on carrier to transfer paper An image forming apparatus for forming an image by performing a light intensity adjustment operation of a light emitting element other than the light emitting element that emits a laser beam that irradiates the synchronization detecting means among the plurality of light emitting elements, Achieves the above objectives.

According to the above configuration, a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array is arranged in the main scanning direction of the latent image carrier. Irradiates the synchronization detection means and the light intensity detection means arranged at a position deviating from the latent image forming area, performs positioning in the main scanning direction based on the detection result of the synchronization detection means, and adjusts the position of the light intensity detection means. While adjusting the light intensity of each light emitting element based on the detection result, when forming an image, the light intensity adjusting operation of the light emitting elements other than the light emitting element that emits the laser beam that irradiates the synchronization detecting means among the plurality of light emitting elements is performed. Since the operation is stopped, the emission intensity of the light-emitting elements other than the light-emitting element to be turned on for synchronization detection, that is, the emission intensity of the light-emitting element unnecessary for operation is reduced to reduce the current supplied to the light-emitting element. Can be, and extends the life of expensive laser light source comprising a light emitting element array such as a LD array, it is possible to reduce the running cost.

In each of the above cases, for example, as set forth in claim 3, the control means turns off a light emitting element other than the light emitting element which emits a laser beam for irradiating the synchronization detecting means or adjusts the light intensity. The operation may be stopped in a standby state.

According to the above configuration, since the light emitting elements other than the light emitting element that emits the laser beam for irradiating the synchronization detecting means are turned off or the light intensity adjusting operation is stopped in the standby state, the synchronization signal securing operation is performed during the standby state. By stopping light emission of light emitting elements not involved, unnecessary light emission of light emitting elements can be prevented, and the life of an expensive laser light source including a light emitting element array such as an LD array can be further extended, resulting in a running cost. Can be further reduced.

Further, for example, as described in claim 4, the image forming apparatus includes a current amount detecting means for detecting an amount of current supplied to each of the light emitting elements of the laser light source;
Selecting means for selecting a light emitting element having the smallest current amount among the current amounts to the respective light emitting elements detected by the current amount detecting means, wherein the control means controls the plurality of light emissions of the laser light source. Among the elements, as the light emitting element that emits a laser beam for irradiating the synchronization detecting means or the light intensity detecting means, a light emitting element having the smallest current amount selected by the selecting means may be used.

According to the above configuration, the amount of current supplied to each light emitting element of the laser light source is detected by the current detecting means, and the light emitting element having the smallest current amount among the detected current amounts to each light emitting element is determined. The light emitting element which is selected by the selecting means and which emits a laser beam for irradiating the synchronization detecting means or the light intensity detecting means among the plurality of light emitting elements of the laser light source is selected by using the light emitting element having the smallest current amount selected by the selecting means. Therefore, it is possible to prevent the bias of deterioration among the plurality of light emitting elements of the laser light source, further extend the life of the expensive laser light source including the light emitting element array such as the LD array, and further reduce the running cost. be able to.

[0023]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 4 are views showing a first embodiment of the image forming apparatus of the present invention, and this embodiment corresponds to claims 1 to 3. FIG.

FIG. 1 is a block diagram of a main part of a digital copying machine 1 to which a first embodiment of an image forming apparatus according to the present invention is applied.

In FIG. 1, a digital copying machine 1 is a VP
U2, IPU3, GAVD4, LD control unit 5, LD (La
ser Diode) array 6, image memory 7, CPU (Centra
l Processing Unit) 8, ROM (Read Only Memory)
9, RAM (Random Access Memory) 10 and operation unit 1
The main components are an internal system bus 12 and the like.
Connected by The VPU2 and IPU3 are:
The GAVD 4, the LD control unit 5, and the LD array 6 are provided in a scanner unit 13 that reads an image of a document.
Is provided in the printer unit 14 for recording and outputting an image on recording paper. The internal system bus 12, scanner unit 13, and printer unit 14 are connected by an I / F 15.

The VPU 2 performs A / D conversion of analog image information of the original read by the scanner unit 13 to perform black offset correction, shading correction and pixel position correction, and outputs the result to the IPU 3. The input image information is subjected to predetermined image processing, for example, resolution conversion and size conversion for a binary image,
The image information after the image processing is transferred to the image memory 7 via the VD 4 or the I / F 15.

The image memory 7 is composed of a large-capacity RAM or a hard disk, and under the control of the CPU 8, image information read by the scanner unit 13 or data transmitted from an external device (not shown), for example, a personal computer or the like. (Image information) is temporarily stored, and is read out as needed.

The GAVD 4 includes an IPU 3 and an image memory 7.
The GAVD 4 operates under the control of the control unit 8 to control the operation of the printer unit 14.

The LD controller 5 operates under the control of the GAVD 4 to turn on and off the LD array 6 in accordance with the input image information, and emit exposure light modulated in accordance with the image information. .

The LD array (laser light source) 6 has a large number of light emitting elements 6a to 6n arranged in a line (array), and each of the light emitting elements 6a to 6n is turned on and off under the control of the LD control unit 5. The device operates to emit exposure light (laser beam) modulated according to image information. The plotter unit 14 will be described later in detail.

The ROM 9 stores various programs such as a basic program as the digital copying machine 1 and a later-described LD array lighting control processing program, and stores various data necessary to execute these various processing programs in advance. Stored.

The control section (control means) 8 controls each section of the digital copying machine 1 based on a program in the ROM 9 while using the RAM 10 as a work memory, and executes a basic sequence as the digital copying machine 1 ,
An LD array lighting control process described later is executed.

The operation unit 11 includes various operation keys such as a start key and a function key, and also includes a display (for example, a liquid crystal display). Various commands necessary for operating the digital copier 1 are provided from the operation keys. Is displayed on the display, the contents of the command input from the operation keys and various information notified from the digital copying machine 1 to the operator are displayed.

As shown in FIG. 2, the printer section 14 is an electrophotographic optical writing section, and includes the GAVD 4 and the LD array 6 as well as the semiconductor laser drive circuit 21 as the LD control section 5. A current detection circuit (current amount detection means) 22, a photodetector (light intensity detection means) 23,
APC control unit 24, polygon mirror 25, fθ lens 2
6, a photosensitive drum (latent image carrier) 27, a photodetector (synchronization detecting means) 28, and the like.

The printer unit 14 converts the laser beam emitted forward from each of the light emitting elements 6a to 6n of the LD array 6 into
The laser beam is collimated by a collimator lens (not shown) and deflected by a polygon mirror 25, and the laser beam is linearly converted in the main scanning direction indicated by an arrow in FIG. Then, writing is performed on the photoreceptor drum 27, which is rotationally driven and uniformly charged, to form an electrostatic latent image. On the photosensitive drum 27 on which the electrostatic latent image is formed, a toner (developer) is applied by a developing unit (not shown) to form a toner image, and the formed toner image is transferred to recording paper by a transfer unit (not shown). Then, a toner image (developer image) is formed on the recording paper. The recording paper onto which the toner image has been transferred is conveyed to a fixing unit (not shown), where the recording paper is heated and pressed to fix the toner image, and then discharged onto a discharge tray (not shown) of the digital copying machine 1.

On the other hand, the photosensitive drum 27 after the transfer is completed
Is further rotated and discharged by a discharging unit (not shown), cleaned by a cleaning unit, uniformly charged again by a charging unit, and used for the next image formation.

The photodetector 28 is, for example, a photodiode or the like, and is provided outside the information writing area in the main scanning direction of the photosensitive drum 27. The photodetector 28 is irradiated with the laser beam deflected by the polygon mirror 25, detects the irradiated laser beam, and outputs a synchronization detection signal to the GAVD4.

The GAVD 4 controls the timing based on the synchronization detection signal input from the photodetector 28 to apply the input image information signal to the semiconductor laser drive circuit 21.
The semiconductor laser drive circuit 21 drives the LD array 6 via the current detection circuit 22 based on the image information signal from the GAVD 4. The LD array 6 also emits a laser beam from each of the light emitting elements 6a to 6n to a photodetector 23 provided at the rear, and the photodetector 23 is incident by using a photodiode or the like, for example. The light intensity of the laser beam is detected and output to the APC control unit 24.

The APC control section 24 operates under the control of the control section 8 to control the semiconductor laser drive circuit 21 in accordance with the output signal of the photodetector 23 and to control the output light quantity of the LD array 6 to be constant. , So-called APC control is performed. Specifically, the APC control unit 24 adjusts and holds the driving power of each light emitting element of the LD array 6 by an external signal so that the output light quantity of each light emitting element becomes constant.

The current detection circuit 22 is provided for each of the light emitting elements 6a to 6n of the LD array 6,
By detecting the current values of the light emitting elements 6a to 6n during the APC control of the light emitting elements a to 6n, it is determined whether or not the current is flowing most in any of the light emitting elements 6a to 6n, and as a result, the deterioration of the light emitting elements 6a to 6n is not advanced. The current detection circuit 22 includes the light emitting elements 6a to 6n
Is output to the control unit 8 via the GAVD4 and the GAVD4.

That is, as shown in FIG. 3, the current detection circuit 22 includes a resistor R1 for each of the light emitting elements 6a to 6n of the LD.
A resistor R5, an operational amplifier 31 and an A / D converter 32 are provided, and a current flowing through each of the light emitting elements 6a to 6n of the LD array 6 is supplied to the semiconductor laser drive circuit 21 and each of the light emitting elements 6a to
6n, the voltage value of the resistor R1 inserted between
2 to the operational amplifier 31 via the resistor 2 and the resistor R3.
Output to 2. The A / D converter 32 converts an analog voltage value into a digital value, outputs the digital value to the GAVD4,
D4 further outputs this detection result to the control unit 8.

The control unit 8 controls an APC (to be described later) based on the current values of the light emitting elements 6a to 6n input from the GAVD 4.
Lighting / flashing control processing of the light emitting elements 6a to 6n in the control processing is performed.

Next, the operation of the present embodiment will be described. In the digital copying machine 1 of the present embodiment, among the plurality of light emitting elements 6a to 6n of the LD array 6, the light emitting elements 6a belonging to one of the channel-divided light emitting elements 6a to 6n
To 6n are used when performing synchronization detection and APC control, and the other light emitting elements 6a to 6n are turned off, and L
The life of the D array 6 is extended.

In the following description, it is assumed that the plurality of light emitting elements 6a to 6n of the LD array 6 are divided into four channels (channel ch1 to channel ch4). Has an image forming state in which an image is recorded and output based on image information, and a standby state in which the image forming apparatus waits for input of image information.

That is, the digital copying machine 1 records an image in the printer unit 14 based on image information of a document read by the scanner unit 13 or image information input from an external device. Performs APC control processing via GAVD4.

As shown in FIG. 4, in the image forming state, the control section 8 needs to stabilize the light output of the LD array 6 during the image forming, and thus performs the APC operation processing as needed. In FIG. 4, for example, once the synchronization detection is performed, the control unit 8 performs the APC operation on all the channels ch1 to ch4 as shown in the image forming state area of FIG. In this case, among the plurality of channels ch1 to ch4,
A for only one of the channels ch1 to ch4
The PC operation may be performed.

When the image forming operation is completed and the operation mode of the digital copying machine 1 shifts from the image forming state to the standby state, the control unit 8 shifts to the standby state, and after about two times,
The APC operation is performed on all the channels via the GAVD4. Thereafter, in order to secure a synchronization signal, a predetermined channel, for example, as shown in FIG.
The synchronization detection process and the APC operation are performed only on the channel 1, and the other channels ch2 to ch4 stop lighting the light emitting elements of the channels ch2 to ch4 and stop outputting the signal for the APC operation.

In order to perform the forced lighting / stopping of the light emitting elements 6a to 6n for synchronization detection and APC operation and the output / stopping of the APC signal, for example, an internal register for making various settings is provided in the GAVD 4, and Register to control unit 8
By setting, the stop can be performed. For example, a flag for turning off the data signal of each channel ch1 to ch4 and a flag for stopping the APC signal of each channel ch1 to ch4 are provided as registers, and the control unit 8 sets this register.

The control unit 8 can determine whether the digital copying machine 1 is in the standby state or the image forming state, for example, based on whether the main motor is on or off. .

As described above, the digital copying machine 1 of the present embodiment has a predetermined light emitting element among the plurality of light emitting elements 6a to 6n of the LD array 6 in which the plurality of light emitting elements 6a to 6n are arranged in an array. The laser beams emitted from 6a to 6n are irradiated on a photodetector 28 located at a position outside the latent image forming area in the main scanning direction of the photosensitive drum 27, and based on the detection result of the photodetector 28. When performing image formation while performing alignment in the main scanning direction, among the plurality of light emitting elements 6a to 6n of the LD array 6, the light emitting elements 6a to 6n (channel c) for emitting a laser beam for irradiating the photodetector 28 are used.
h1 to ch4) and other light emitting elements 6a to 6n (channel c)
The light emitting elements 6a to 6n) of h1 to ch4 are turned off.

Therefore, the light emitting element 6a unnecessary for operation
6n can be stopped to extend the life of the expensive LD array 6 including the plurality of light emitting elements 6a to 6n,
Running costs can be reduced.

The digital copier 1 of the present embodiment
Are light-emitting elements 6a to 6n (light-emitting elements 6a of channels ch1 to ch4) other than light-emitting elements 6a to 6n (channels ch1 to ch4) for emitting a laser beam for irradiating the photodetector 28 among the plurality of light-emitting elements 6a to 6n. To 6n) of the light intensity adjustment operation (APC operation) is stopped.

Therefore, the light emission intensity of the light emitting elements 6a to 6n other than the light emitting elements 6a to 6n to be turned on for synchronization detection,
That is, the current supplied to the light emitting elements 6a to 6n can be reduced by lowering the light emission intensity of the light emitting elements 6a to 6n that are unnecessary for operation. In particular, in the present embodiment, the light emitting elements 6a to 6n that are unnecessary for operation are 6n can be turned off. Therefore, an expensive LD including a plurality of light emitting elements 6a to 6n
The life of the array 6 can be extended, and the running cost can be reduced.

Further, the digital copying machine 1 of the present embodiment
Is to turn off or adjust the light intensity of the light emitting elements 6a to 6n (the light emitting elements 6a to 6n of the channels ch1 to ch4) other than the light emitting elements 6a to 6n (the channels ch1 to ch4) for emitting the laser beam irradiated to the photodetector 28. The operation (APC operation) is stopped in a standby state of the digital copying machine 1.

Therefore, the light emitting elements 6a to 6n that are not involved in the synchronization signal securing operation are stopped during standby, and unnecessary light emission of the light emitting elements 6a to 6n can be prevented. The life of the expensive LD array 6 composed of 6a to 6n can be further extended, and the running cost can be further reduced.

FIGS. 5 to 7 are views showing a second embodiment of the image forming apparatus of the present invention. In this embodiment, the light emitting element having the smallest current amount is used for synchronization detection and APC operation. This corresponds to claim 4.

This embodiment is applied to a digital copier similar to the digital copier 1 of the first embodiment. In the description of the present embodiment, the first embodiment will be described. The description will be made using the reference numerals used in the embodiment as they are.

In the digital copying machine 1 of the present embodiment, one channel ch of the LD array 6 is in the standby state.
The synchronization detection and the APC operation are performed only for the channels 1 to ch4. At this time, the current values of the light emitting elements 6a to 6n during the APC operation are detected, and the synchronization detection is performed for the channels ch1 to ch4 to which the light emitting element having the smallest current value belongs. Processing and AP
The feature is that the C operation processing is performed.

That is, as shown in FIG. 5, the control unit 8 checks whether the APC operation process is being performed on any of the channels ch1 to ch4 (step S101).
When the PC operation is not performed, the processing is terminated as it is, and the same processing is performed again after a predetermined time.

In step S101, when the APC operation process is being performed, the current
Channel ch1 during APC operation input via D4
When the current values of ch4 to ch4 become the expected values, the current values are stored in the RAM 10 (step S102), and the AP
It is checked whether the C operation has completed one mode (step S
103). The time required for this current value to reach the expected value is A
The control unit 8 obtains, as an expected value, the current value input from the current detection circuit 22 via the GAVD 4 at the time when the elapsed time has elapsed since the PC operation was started. And store it in the RAM 10. The LD array 6 includes a plurality of light emitting elements 6a to 6n
Are divided into a plurality of channels ch1 to ch4. In order to perform an APC operation in each of the channels ch1 to ch4, the same scan is performed a total of n times to obtain a current value.

If it is determined in step S103 that the APC operation has not been completed in one mode (one round), the process proceeds to step S101.
And the same processing is performed again after a predetermined time, and when the APC operation ends in one mode, the light emitting element 6a having the lowest current value
To 6n channels ch1 to ch4 and RAM 10
(Step S104).

When the control unit 8 selects the light emitting elements 6a to 6n having the lowest current value and stores them in the RAM 10 in the above processing, as shown in FIG.
Set ch4.

That is, as shown in FIG.
Checks whether or not it is in the standby state (standby mode) (step S201). If it is not in the standby state, it is in the image forming state, and therefore, as shown in FIG.
h1 to ch4 remain unchanged, and all channels ch1 to c
APC operation processing is sequentially performed for h4 (step S2)
02).

In step S201, when it is not in the standby state, the control unit 8 sets the channels ch1 to ch4 of the light emitting elements 6a to 6n having the lowest current value stored in the RAM 10
Are selected as channels ch1 to ch4 for synchronization detection (step S203), and the selected channels ch1 to ch
The APC operation of the channels ch1 to ch4 other than the channel 4 is stopped, and the standby mode process is performed (step S204).

For example, in FIG. 7, the channel ch3 is the light emitting elements 6a to 6n having the lowest current value, and the channel ch3 having the lowest current value is selected as a channel for synchronization detection. Then, the APC operation process is performed only on the selected channel ch3.

As described above, in the digital copying machine 1 of the present embodiment, the amount of current supplied to each of the light emitting elements 6a to 6n of the LD array 6 is detected by the current detecting circuit 22, and the detected light emitting elements are detected. The light emitting elements 6a to 6n having the smallest current amount among the current amounts to 6a to 6n are selected as the light emitting elements for synchronization detection and light intensity adjustment among the plurality of light emitting elements 6a to 6n of the LD array 6. The light emitting elements 6a to 6n having the smallest current amount are used.

Accordingly, it is possible to prevent the bias of deterioration among the plurality of light emitting elements 6a to 6n of the LD array 6, and to further extend the life of the expensive LD array 6 including the plurality of light emitting elements 6a to 6n. The running cost can be further reduced.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, the case where the present invention is applied to a digital copying machine has been described. However, the image forming apparatus is not limited to the digital copying machine, but may be an electrophotographic system such as a facsimile machine or a printer. The present invention can be generally applied to an image forming apparatus that forms an image.

[0071]

According to the image forming apparatus of the present invention, a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source having a plurality of light emitting elements arranged in an array. Irradiates the synchronous detection means disposed at a position outside the latent image forming area in the main scanning direction of the latent image carrier,
In performing image formation while performing position adjustment in the main scanning direction based on the detection result of the synchronization detection unit, light emission of a plurality of light-emitting elements of the laser light source other than the light-emitting element that emits a laser beam that irradiates the synchronization detection unit is formed. Since the element is turned off, unnecessary lighting of the light emitting element is stopped, and L
The life of an expensive laser light source including a light emitting element array such as a D array can be extended, and the running cost can be reduced.

According to the image forming apparatus of the present invention, a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array is latent. Irradiates the synchronization detecting means and the light intensity detecting means arranged at a position deviating from the latent image forming area in the main scanning direction of the image carrier, and performs positioning in the main scanning direction based on the detection result of the synchronization detecting means. In addition, while adjusting the light intensity of each light emitting element based on the detection result of the light intensity detecting means, when forming an image, of the plurality of light emitting elements other than the light emitting element that emits a laser beam that irradiates the synchronization detecting means. Since the light intensity adjustment operation of the light emitting element is stopped,
The emission intensity of the light-emitting elements other than the light-emitting element to be turned on for synchronization detection, that is, the current supplied to the light-emitting element by reducing the emission intensity of the light-emitting element unnecessary for operation can be reduced,
The life of an expensive laser light source including a light emitting element array such as an LD array can be extended, and the running cost can be reduced.

According to the image forming apparatus of the present invention, since the light emitting elements other than the light emitting element that emits the laser beam for irradiating the synchronization detecting means are turned off or the light intensity adjusting operation is stopped in the standby state, Light emission of light emitting elements not involved in the synchronization signal securing operation can be stopped during standby to prevent unnecessary light emission of unnecessary light emitting elements, and the life of expensive laser light sources including light emitting element arrays such as LD arrays. And the running cost can be further reduced.

According to the image forming apparatus of the present invention, the amount of current supplied to each light emitting element of the laser light source is detected by the current detecting means, and the amount of current detected to each light emitting element is detected. The light emitting element having the least amount of current is selected by the selecting means, and the current amount selected by the selecting means is selected as a light emitting element which emits a laser beam to be applied to the synchronization detecting means or the light intensity detecting means among the plurality of light emitting elements of the laser light source. Since the light emitting element having the least number of light emitting elements is used, it is possible to prevent the bias of deterioration among the plurality of light emitting elements of the laser light source, and to further extend the life of the expensive laser light source including the light emitting element array such as the LD array. In addition, the running cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a digital copying machine to which an image forming apparatus according to a first embodiment of the present invention is applied.

FIG. 2 is a detailed configuration diagram of a printer unit in FIG. 1;

FIG. 3 is a detailed circuit diagram of a main part of the current detection circuit of FIG. 2;

FIG. 4 is a diagram showing timings of a synchronization signal, an APC signal of each channel of an LD array, and data in an image forming state and a standby state of the digital copying machine of FIG. 1;

FIG. 5 is a flowchart illustrating a minimum current value light emitting element selection process performed by a digital copying machine to which an image forming apparatus according to a second embodiment of the present invention has been applied.

FIG. 6 is a flowchart illustrating synchronization detection output channel setting processing by a digital copying machine to which the second embodiment of the image forming apparatus of the present invention has been applied.

FIG. 7 is a diagram showing a synchronization signal, an APC signal of each channel of an LD array, and data timing in a digital copying machine to which the second embodiment of the image forming apparatus of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Digital copying machine 2 VPU 3 IPU 4 GAVD 5 LD control part 6 LD array 7 Image memory 8 Control part 9 ROM 10 RAM 11 Operation part 12 Internal system bus 13 Scanner part 14 Printer part 15 I / F 21 Semiconductor laser drive circuit 22 Current detection circuit 23 Photodetector 24 APC control unit 25 Polygon mirror 26 fθ lens 27 Photoconductor drum 28 Photodetector 31 Operational amplifier 32 A / D converter R1 to R5 Resistance

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/113 B41J 3/00 D 5F071 / 23 103 H04N 1/04 104A F-term (Reference) 2C362 AA13 AA53 AA73 AA75 BA67 BA69 BB29 BB33 2H045 BA23 CA88 CB42 2H076 AB06 AB12 AB22 AB35 AB67 DA04 5C072 BA20 HA02 HA06 HA13 HB02 HB04 HB08 HB11 HB13 XA01 XA05 5C074 AA15 BB03 BB26 CC02 CC02 DD08 DD03 AB02 AB02 GA12 GA37

Claims (4)

[Claims] 1. A laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source in which a plurality of light emitting elements are arranged in an array form a latent image in a main scanning direction of a latent image carrier. A laser beam modulated on the basis of image information from the laser light source while irradiating the synchronization detection means disposed at a position outside the area and performing alignment in the main scanning direction based on the detection result of the synchronization detection means Irradiates the latent image carrier in the main scanning direction to form an electrostatic latent image on the latent image carrier, and applies a developer to the latent image carrier on which the electrostatic latent image is formed to develop the latent image carrier. An image forming apparatus that forms a developer image by transferring the developer image on the latent image carrier onto transfer paper to form an image. The source for emitting a laser beam for irradiation An image forming apparatus characterized by comprising control means for turning off the light-emitting element other than the element. 2. A method for forming a latent image in a main scanning direction of a latent image carrier by using a laser beam emitted from a predetermined light emitting element among a plurality of light emitting elements of a laser light source having a plurality of light emitting elements arranged in an array. Irradiates the synchronization detection means and the light intensity detection means arranged at a position outside the area, performs alignment in the main scanning direction based on the detection result of the synchronization detection means, and adjusts the detection result of the light intensity detection means. Irradiating the latent image carrier with a laser beam modulated based on image information from the laser light source in the main scanning direction while adjusting the light intensity of each light emitting element based on the A latent image is formed, a developer is applied to the latent image carrier on which the electrostatic latent image is formed and developed to form a developer image, and the developer image on the latent image carrier is transferred to transfer paper. Image forming apparatus that forms an image by transferring to An image forming apparatus characterized by comprising control means for stopping the light intensity adjustment operation of the light emitting elements other than the light emitting element for emitting a laser beam to be irradiated to the synchronization detection unit among the plurality of light emitting elements. 3. The control device according to claim 2, wherein the control unit performs a standby state to turn off a light emitting element other than the light emitting element that emits a laser beam for irradiating the synchronization detecting unit or to stop the light intensity adjustment operation. The image forming apparatus according to claim 1 or 2. 4. An image forming apparatus, comprising: a current amount detecting means for detecting an amount of current supplied to each of the light emitting elements of the laser light source; and a current amount to each of the light emitting elements detected by the current amount detecting means. Selecting means for selecting a light emitting element having the smallest current amount among the light emitting elements, wherein the control means irradiates the synchronization detecting means or the light intensity detecting means among the plurality of light emitting elements of the laser light source. The image forming apparatus according to claim 1, wherein a light emitting element having the smallest current amount selected by the selection unit is used as the light emitting element that emits a laser beam. 5.