JPH0298462A - Quantity of luminescence control device - Google Patents

Abstract

PURPOSE:To detect a warning about the life of a light emitting element, alarm it and thereby avoid any inconvenience due to the sudden expiration of a laser life by comparing for analyzing a drive current value stored in advance against a specified quantity of luminescence with a drive current value detected at any moment. CONSTITUTION:A threshold value data memory is provided that stores the data value of a threshold value current at which a laser emits light. This memory stores the data value of a D/A converter 2 for coarse control when the laser begins light emission. After this, 80% of the condensation value is determined by the D/A converter for coarse control, and 80% of the condensation value of the D output data memory after FLAG-A flag which indicates that a specified intensity of luminescence has been reached, is set and is subtracted by the data value of the threshold value data memory. Then the life of a laser is determined by the difference. If the life of the laser expires, LBP is interrupted regardless of a condition. Thus any significant inconvenience can be prevented by forecasting the laser life before the interruption of the LBP.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light amount control device for stabilizing the light amount of a light emitting element, such as a semiconductor laser used in a laser beam printer. It is something that makes you

[Prior Art] Conventionally, laser beam intensity control in laser beam printers (hereinafter referred to as LBP) has been performed using the APC method (Auto
Power Control method) is used, and is currently adopted in most LBPs.

With this APC method, a laser beam is emitted, the light is received by a light-receiving element, the amount of light is converted into an amount of electricity by photo-electrical conversion, and this amount of electricity is compared with a predetermined reference value. If it is determined that this is the case, the laser drive current is increased to increase the amount of light; on the other hand, if the amount of laser light is large, the laser drive current is decreased to decrease the amount of light. Below, this control will be performed using La5e.
It is abbreviated as rAPC.

In the current LBP, this La5erAP
C was executed at the start of printing and at paper intervals during printing. Note that the paper interval here refers to a non-image area shifted from the image forming area on the drum in the drum rotation direction (laser sub-scanning direction).

In this method, specifically, APC-STA is
An RT request is generated from the central processing unit of the LBP, thereby passing through the La5erA PC all at once.

That is, when there is an APC-5TART request, the laser drive current is cleared once to the θ layer A, the laser is forced to turn on, and the laser drive current is stepped up to gradually increase. At each step, the amount of electricity from the light receiving element is compared with a predetermined value, and when the amount of electricity from the light receiving element matches the predetermined value, the increase in the laser drive current is stopped and the laser is forced to turn on. The value at that time is held until the first APC-9TART request occurs. Therefore, in this method, the laser light intensity is stepped up at one paper interval and the laser light intensity is increased to a predetermined light intensity. Since the laser is extinguished when it reaches this point, the laser is continuously turned on and scans the photoreceptor drum for several lines to several tens of lines.

Hereinafter, Laaer A PC using this method will be referred to as continuous inter-sheet Laaer A PC.

Further, as another method of La5erAPC, there is a method of executing La5erAPC when the laser raster scan scans an area other than the surface of the photoreceptor drum. Note that the scan area by this raster scan is
A scanning area other than on the surface of the photosensitive drum, that is, an area shifted from the image forming area on the drum in the axial direction of the drum (main scanning direction of the laser) is referred to as a non-drum area.

Now, LBP image formation is done by raster scanning.
Executed line by line. Each line is synchronized with a horizontal synchronization signal (hereinafter referred to as BD double signal) and is established as an image by transmitting image information.

Further, in order to obtain the BD double signal, the LBP lights a laser at each line interval (hereinafter, the laser lighting instruction signal is referred to as the UNBL signal).

Then, La5er APC is executed in the non-drum area in synchronization with the UNBL signal generated at each line interval. Hereinafter, this method will be applied to the non-drum area La.
It is called 5erAPC.

With the Laaer A PC as described above, the laser light intensity is controlled to be constant at all times during image formation.
We are trying to improve the image quality.

That is, in general, a laser gradually deteriorates as it is used and eventually stops emitting light. The degree of this deterioration varies depending on the individual laser, but
Someday, when the lifespan reaches the end, it will no longer be possible to control the light intensity using La5er APC, so conventionally, La5erA
When the PC becomes disabled and a predetermined amount of light cannot be obtained, it is determined that the laser has reached the end of its life, and the laser is replaced.

[Problems to be Solved by the Invention] However, in the above conventional technology, the La5erA PC
It can only be determined that the laser has reached the end of its lifespan when it is no longer possible to control the amount of light. That is, when the desired amount of light is not reached even if the laser drive current is applied to the maximum level by the light amount control device, it is determined that the life span has come to an end.

Therefore, for users using LBP, the laser suddenly reaches the end of its lifespan during printing and the printing operation is interrupted, so it is necessary to call a service person to replace the laser, which causes the following inconveniences: .

(A) If the laser lifespan can be detected in advance, it can be dealt with during service maintenance, but if the laser lifespan suddenly reaches its end, the LBP cannot be used until a service person comes.

(B) Particularly in the case of LBP, those used in facsimile printers operate unattended all night, so if the laser suddenly reaches the end of its lifespan at night, the facsimile machine will be out of service that day. Shimafu.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light amount control device that has a self-diagnosis function that allows advance judgment of the laser lifespan, and can avoid problems caused by sudden laser lifespans.

[Means for Solving the Problems] The present invention is provided in an image forming apparatus that forms a latent image on a photosensitive medium by raster scanning the light emitted from a light emitting element with respect to the photosensitive medium, A light amount control device that detects the amount of light from the light emitting element using a light receiving element and controls the amount of light by adjusting a drive current supplied to the light emitting element based on the detection result, wherein the amount of light emitted from the light emitting element is set to a first predetermined value. a first storage means for reading and storing a drive current value when the light emission amount of the light emitting element reaches a second predetermined value; and a second storage means for reading and storing a drive current value when the light emission amount of the light emitting element reaches a second predetermined value. , a calculation means for calculating the difference between the drive current values stored in each of the storage means, a detection means for detecting the life expectancy of the light emitting element based on the calculation by the calculation means, and a prediction means for detecting the life expectancy of the light emitting element based on the calculation by the calculation means. The present invention is characterized by having a warning means for warning when a notice is detected.

The present invention also provides a storage means for reading and storing a driving current value when the amount of light emitted from the light emitting element reaches a predetermined value, and a detection means for detecting a predicted life of the light emitting element based on data in the storage means. and a warning means for giving a warning when the detection means detects an end-of-life notice of the light emitting element.

[Function] In the present invention, a prediction of the lifespan of a light emitting element is detected by comparing and analyzing a drive current value stored in advance corresponding to a predetermined amount of light emission and a drive current value detected at the present time, and this is detected. By issuing a warning, it is possible to avoid inconveniences caused by the sudden expiration of the laser life.

[Example] Hereinafter, an example of the present invention will be described in detail based on one drawing.

First, before explaining the examples, a table of contents will be shown.

3-c4 is a circuit diagram showing the basic configuration of an LBP according to an embodiment of the present invention.

This LBP includes CPUI, D/A converters 2 and 3
, constant voltage circuits 4 and 6, a current switch circuit 7, a laser 8, an AND circuit 9, and a D-type flip-flop 10.

The CPUI controls the entire device of this embodiment.
It has a built-in A/D converter that converts external analog input to digital.

D/A converters 2 and 3 are connected to CPU baud) P2
and port P1, and these boats P2, Pl
The D/A converter 2 of the former is used for coarse adjustment, and the D/A converter 3 of the latter is used for fine adjustment.

Note that if the CPUI has a built-in D/A converter, these external D/A converters 2 and 3 can be omitted.

The first constant voltage circuit 4 includes a summing amplifier 5 and the like that amplifies the sum voltage v1 of the output voltage of the coarse adjustment D/A converter 2 and the output voltage of the fine adjustment D/A converter 3, and outputs a constant voltage v2. Output. In other words, the output voltage v2 is varied by the data values supplied to the D/A converters 2 and 3 from the CPU ports P2 and Pl.

The second constant voltage circuit 6 outputs an output voltage v3 determined by a Zener diode ZD. Note that in this example, the output voltage v3 is a fixed voltage, but
Similarly to the first constant voltage circuit 4, a D/A converter may be provided so that the output voltage v3 can be varied from the CPUI.

The current switch circuit 7 switches whether or not to flow the laser drive current iL determined by the output voltages v2 and v3 of the respective constant voltage circuits 4 and 6 and the resistors R1 and R2 to the laser 8. Determine on/off depending on the output status. That is, if the output of the AND circuit 9 is "low", the laser drive current f1 is passed through the laser 8, and if it is "high", the laser drive current i is passed through the previous stage transistor TRI.

The laser 8 has a built-in laser diode LD and a pin photodiode PD as a light receiving element.The laser diode LD's light is received by the pin photodiode FD, and the voltage v4 determined by the polyurethane VR is converted to the voltage A of the cput.
/D converter input terminal. Note that the light receiving element may be an external one.

The AND circuit 9 has an oven collector configuration and is a two-person type that inputs a video signal sent from an external host control device and an output signal from port P3 of the CPUI.

In the D type flip 70 tube lO, the above video signal is input to the clock input terminal, the D input terminal is pulled up, and the clear input terminal and Q output terminal are connected to the CPU.
I port) connected to P5 and P4.

1-b The main port's CPUI is controlled by a control signal sent from the control device.

Examples of such control signals include the following.

(A) Arc-RESET signal When this APC-RESET signal becomes TRUE.

No APC operation is performed, the laser power is maintained at OmW state, and the device is placed in a reset state.

In this embodiment, the APC-RESET signal becomes FALSE when the print operation is started, and becomes TRUE when the print operation ends. However, even if printing is in progress, TRIJE will occur immediately in the event of various failures such as a jam, an open door, or a scanner failure.

CB) Arc-9TART signal this APC-! The JTAR signal is a timing signal, and on the leading edge of this signal becoming TRUE, the APC12
) production begins. In other words, the above A P C-RESE
After the T signal becomes FALSE, the APC-9TAR
When the T signal is received, the APC operation continues so that the output of the laser 8 becomes a predetermined power. In this embodiment, when the APC-3TART signal is received again, the previous APC operation is stopped and a new APC operation is started.

Furthermore, if the APC-5TART signal is received again during APC operation, that APC
-9TART signal may be ignored;
When restarting the APC operation, it may be started from the initial state or from an intermediate state.

Further, in this embodiment, the APC-5T is activated only when the APC-RESET signal becomes FALSE.
It is configured to be able to receive ART signals, and
While the P C-RESET signal is TRUE, the A P
The C-3TART signal will be ignored.

Furthermore, in this embodiment, the scanner is rotated only during printing. Therefore, for safety reasons, the laser is not turned on until the scanner rotation reaches steady rotation. Therefore, the APC-5TART signal is the APC-RESET signal. becomes FALSE, and TRLfE does not become true until the scanner rotation reaches steady rotation.

(C) UNBL signal This UNBL signal is a signal necessary to generate the above-mentioned BD double signal, especially in LBP. During raster scanning, after each line ends, the BD double signal of the next line is detected. It lights up a laser. and,
After the BD double signal is detected, it becomes FALSE at a predetermined timing, and the laser lighting for generating the BD double signal ends.

Then, the control device synchronizes with the BD double signal and sends out a video signal after a predetermined time.

In other words, the UNBL signal becomes TRUE for a predetermined period of time in order to generate the BD signal, and the laser is turned on during this RUE period.If the HD double signal is not detected within this period, a BD error occurs. Since the laser continues to be lit until the BD double signal is detected, the UNBL signal continues to be TRUE. Furthermore, if a BD error continues for a predetermined period of time or more, a BD failure occurs and the LB
P interrupts the printing operation and sends the UNBL signal to FA.
Set to LSE and stop the laser lighting for detecting the BD double signal.

Note that during the TRUE period of this UNBL signal, normally an area other than the ending end of the photoreceptor drum to the starting end of the raster scan area, that is, the line scanned by the polygon mirror is scanned outside the drum area. region(
(non-drum area).

(D) Paper spacing signal This signal indicates whether or not there is a gap between print sheets during printing in LBP, and has different timing depending on the size of the paper to be printed.

Note that this paper spacing signal is

When TRUE, it means that there is a paper gap.

(E) Other In addition to the above input control signals, for example, drum sensitivity information is provided to switch the target value for performing APC according to the sensitivity of the photoreceptor drum used and to perform APC with a light amount suitable for the drum sensitivity. In some cases.

On the other hand, the following signals are available from the present LBP device in response to the input control signal as described above.

(A) Laser error signal This is a signal that informs the control device of a laser failure, etc.

(B) UNBL error signal This is a signal that informs that the UNJIL signal is not input.

(C) Arc-RDY signal This is a signal indicating that APC operation is normal.

Note that these control signals are merely examples, and are not particularly limited in executing the Arc operation.

Next, the laser drive current iE will be explained.

Normally, the maximum driving current of a semiconductor laser is about 120 A. Therefore, in order to guarantee 120 A, the Laser Drino (considering the variations in circuit constants and fluctuations)
It is necessary to design the chip light amount value (TYP) to be approximately 140 mA. On the other hand, in LBP, the stability of the laser light amount is required to be about ±5% with respect to the tarp value.

In addition, the laser used for LBP has a maximum of 0.6cm according to the standard.
It is necessary to cover devices with slope efficiency of W/mA.

Furthermore, the amount of laser light used for LBP is at least about 1-2 on the chip.

Therefore, in order to keep the light intensity fluctuation within 5% (1mW
Xo, 05) 10.8mW/mA 0.0083
mA140, A10.083 layer A'': 1B87 steps, B. In other words, the amount of current per step to maintain 5% is 0.083i+A, and 1687 steps are required.

Therefore, if one D/A converter is used to compensate, 11 bits are required. However, with an 11-bit D/A converter, it is difficult to actually implement this in consideration of resolution.

Therefore, by roughly adjusting the light amount up to a predetermined ratio with respect to the target light amount, and finely adjusting the rest, D
The number of bits of the /A converter can also be reduced, and a general-purpose D/A converter can be used.

Therefore, in this embodiment, the processing is shared between the coarse adjustment D/A converter 2 and the fine adjustment D/A converter 3. Specifically, the rough adjustment D/A converter 2 is 0.5 layer A.
/step, and the fine adjustment D/A converter 3 is set to 0.05.
Set to Meal A/Step. This gives (0,5 intestines A/step × 255 bits) + (0
, 05 layer AI steps x 255 bits) = 127
．． 5 Intestine A +12.75 ■^= 140.
25 mA (0.05mAX 0.8mW/mA) / 1ml
$ = 0.03 = 3%.

In other words, it is necessary to separate the D/A converter 2 for coarse adjustment and the D/A converter 3 for fine adjustment, and use 8-bit D/A converters for each in order to maintain a maximum drive current of 140 A and light intensity stability of 5% or less. .

Note that this does not necessarily mean that it is necessary to use an 8-bit D/A converter.

For the above reasons, this basic circuit uses an 8-bit coarse adjustment D/A converter 2 and a fine adjustment D/A converter 3.
is used to adjust the laser light intensity.

Next, a configuration for determining the laser drive current i1 will be described.

The laser drive current i1 is applied to each D/A converter 2 and 3.
is determined by the addition result of each output voltage. In other words,
It is proportional to the data value from the CPUI for each D/A converter 2 and 3.

Specifically, each output voltage Vl of each D/A converter 2 and 3 is multiplied by a constant, and the output voltage of the first constant voltage circuit 4 is
It becomes 2. On the other hand, the second constant voltage circuit 6 has a fixed output voltage v
3 is output. Therefore, the electric currents f & i 1 and 12 flowing through the resistors R1 and R2 are i l = (V2 - V3 )/R + i 2
= V3 / R2, so when the notator value to each D/A converter 2.3 is "00H", R is set so that i+ = iz.
+, R2, V+, and V2 are set for each D/A.
When the output voltage v2 of the first constant voltage circuit 4 is increased by converters 2 and 3, i+>i? The relationship becomes,
A differential current of (il-12) flows through the current switch circuit 7. This differential current becomes the laser drive current i [,
Therefore, the laser drive current i [is iL= ((V2-V3)/R+'1-V3
/R2.

Here, since V3, R1, and R2 are fixed values, the laser drive current iL is determined by the output voltage 2 of the first constant voltage circuit 4. That is, by controlling the data values of ports PI and P2 of the CPUI supplied to each D/A converter 2 and 3, a laser drive current i1 corresponding to the data value can be obtained.

Next, an overview of the control operation of the La5erA PC will be explained. Note that the details will be described later.

When the APC-RESET signal becomes FALSE, the scanner is in steady rotation, and the APC-9TART signal becomes TRUE, the APC operation is started based on the leading edge of this APC-5TART signal.

First, the CPUI initializes the data values of baud) P2 and PI for each D/A converter 2 and 3. Note that the data for this initialization is not limited to zero clear, as will be described later.

Next, the CPU sets baud P3 to "low" so that the laser drive current i1 flows through the laser diode LD side (hereinafter, this state is referred to as laser on, and conversely, the laser drive current i1 (The state in which the laser current does not flow through the laser diode LD side is called laser off), and from this laser on state, the output voltage v2 of the first constant voltage circuit 4 is increased.

Initially, since the laser drive current iL is less than the threshold current Ith specific to the laser 8, the laser 8 does not emit light even in the laser on state, so CP
The input voltage to the A/D converter terminal of the UI is VCC. Then, as the laser drive current i1 is increased,
Eventually, the laser 8 begins to emit light, and the input voltage to the A/D converter terminal of the CPUI falls below VCC. In order to increase the output voltage v2 of the first constant voltage circuit 4 until this input voltage reaches a desired value, the CPU 1 counts the output data values of baud P2 and Pi for each D/A converter 2 and 3. It's getting more and more popular.

Note that various procedures can be adopted as the procedure for counting up the output data value.

For example, the threshold current It at which the laser 8 starts emitting light
Until h, the rough adjustment D/A converter 2 counts up several steps in one operation, and when the threshold current Ith is reached, the coarse adjustment D/A converter 2 counts up until 90% of the next light intensity target value. It is also possible to count up one step at a time and use the fine adjustment D/A converter 3 to count up the remaining 10%.

For example, the rough adjustment D/A converter 2 is used to raise the target value to 70%, the data value at that time is stored, and the coarse adjustment D/A converter 2 is used to raise the target value to 80%, and the remaining 20% is stored. Use the fine adjustment D/A converter 3, and next time, use the memorized 7
It may be possible to start from a data value of 0%.

・Furthermore, for example, the previous data values of the rough adjustment D/A converter 2 and fine adjustment D/A converter 3 are peak-held, and from the next time onwards, APC is performed by increasing or decreasing the peak-held data values. You can do it like this.

That is, in the present invention, various specific procedures for increasing the laser light intensity to the desired target value by each D/A converter 2 and 3 can be adopted, but basically the basic sequence is as shown in FIG. . However, A
In order to speed up PC operation, it is effective to take measures such as those described above.

1-c tree Furthermore, the basic circuit shown in FIG. 1(a) is merely an example, and is not limited thereto.

FIG. 1(b) is a circuit diagram showing a modification of the basic circuit.

In FIG. 1(b), the same components as those in the basic circuit shown in FIG. 1(a) are denoted by the same reference numerals, and the description thereof will be omitted.

In this modification, the output voltage V'' of the constant voltage circuit 4° is C
It is determined in accordance with the data value sent from the PUI to each D/A converter 2 and 3 in the same manner as the basic circuit shown in FIG. 1(a). Then, the laser drive current iL is determined by i[=(V2-(-Vcc))/R1.

Then, depending on the output of the AND circuit 9, the current switch circuit 7° determines whether or not to flow the laser drive current 11 to the laser 8°.

(2) Description of specific control FIGS. 3(a) to 3(k) are flowcharts showing the control operation of the LBP in this embodiment.

Of these, FIG. 3(a) shows the main routine, in which predetermined initialization is executed when the power is turned on, and the I/O
Enter the DLE routine. Note that the APC-RESET routine is performed during initialization.

Next, prior to explaining this specific control, a supplementary explanation of the basic configuration will be given.

(2-a) UNBL signal and UNBL interrupt Although the outline of the UNBL signal has already been described, here we will explain the L
The UNBL signal in BP will be explained.

In this embodiment, the UNBL signal is connected to the external interrupt terminal of the CPUI, and an interrupt request is made at the leading edge of the UNBL signal to enter the UNBL interrupt routine shown in FIG. 3(C).

Further, this UNBL signal is synthesized with a video signal by an AND circuit 9. In other words, the video signal is output as an image signal during a period corresponding to the photoreceptor drum area during the laser beam scanning, and is output as an UNBL signal for forced laser ON outside the photoreceptor drum area.

Then, this UNBL signal continuously becomes TR[JE and maintains the laser-on state until the BD double signal is obtained, and immediately becomes FALSE when the BD double signal is obtained.

Furthermore, as this BD double signal reference, the UNBL signal is TRU from a little before the predetermined time when the next BD double signal is to be obtained.
Make it E. Then, when the next BD double signal is obtained, it is set to FALSE. That is, in a state where the BD double signal can be input normally, the UNBL signal becomes TRUE for a predetermined period at a predetermined period. Note that the period and period during which this UNBL signal becomes TRUE differs depending on each LBP or each resolution, but the period is about 700 S to 2 ms, and the period is about the end of Zoo S even at high speed.

However, if the BD double signal cannot be obtained due to some abnormality such as laser damage or scanner motor failure, the B
It becomes D-RUE continuously until D times signal is obtained. If the TRUE period continues for a certain period of time, a BD detection failure will occur.
The UNBL signal becomes FALSE.

On the other hand, a BD signal generation circuit (not shown) is capable of generating a BD double signal by detecting a light amount level approximately lower than the light amount level at which the photoreceptor drum can react in the wooden LBP. Therefore, when the laser starts emitting light, the UN
The BL signal has the period and pulse width (DingRUE) as described above.
period) becomes a pulse signal. Conversely, the UNBL signal remains TRUE until the laser emits light.

By the way, the U of CPU1 due to such UNBL signal
As mentioned above, NBL interrupts are, in principle, UNBL interrupts.
The CPU is executed using the leading edge of the signal as a trigger, but at the first UNBL signal when the laser is not yet emitted, the CPU attempts to enter the first UNBL interrupt, but this interrupt is interrupted by A shown in Figure 3(e). It will be canceled by the PC-5TART routine or the like. Therefore, the actual CPUI UNBL interrupt is
After the laser emits light and the UNBL signal becomes a pulse signal, 1. There will be no UNBL interrupt until the laser emits light.

2-b) Memory and Flags First, in order to execute the La5erAPC of this embodiment, the following memories are prepared.

(A) D output data memory This is the coarse adjustment stage by the coarse adjustment D/A converter 2.
It stores data (hereinafter referred to as D output data) for causing the rough adjustment D/A converter 2 to perform arithmetic processing to obtain a desired light amount value.

(B) D hold data memory This is the coarse adjustment stage by the coarse adjustment D/A converter 2.
When a desired light amount value is obtained using the above output data, the data at this time (hereinafter referred to as D hold data) is stored.

(C) R output data memory This is the fine adjustment stage by the fine adjustment D/A converter 3.
It stores data (hereinafter referred to as R output data) for causing the fine adjustment D/A converter 3 to perform arithmetic processing to obtain a desired light amount value.

(D) R hold data memory This is the fine adjustment stage by the fine adjustment D/A converter 3.
When a desired light quantity value is obtained using the R output data, the data at this time (hereinafter referred to as R hold data) is stored.

Next, the main flags will be explained.

(A) UNBL-IN flag This is a flag that is set in rlJ when a UNBL signal is received.

CB) FLAG-A flag This is a flag that is set in rlJ when the data value at the coarse adjustment stage by the coarse adjustment D/A converter 2 is determined. In this example, for convenience, UNBL-
La5erA P C until the IN flag is set
defined as the launch of Note that this definition is based on La5er
There are no particular limitations when implementing APC.

(C) TABLH-NO flag This is the APC-N0P and Arc-01 to APC flag in the APC-TABLH shown in FIG. 3(b).
-05 execution routines (hereinafter collectively referred to as APC routines) is a selection designation control flag for skipping. In other words, when APC-TABLE is called, the TABLE-NO flag
One of the APC routine programs in the C-TABLE routine is selected and executed. Nao,
In APC-01-APC-04, when the execution conditions of each program are satisfied, it is relayed to the next program, that is, APC-014Arc-02 → Ar
c-03..., and when it is relayed to Arc-05, Arc-05 continues to be executed. However, as will be described later, if the R output data overflows or underflows during the comparison operation, it is returned to APC-02 and relayed to APC-05 to re-execute the program.

(2-c) Timer In FIG. 3(C), there is a timer interrupt, and there is a timer reset/set in other routines.

The function of this timer will be explained in the UNBL error section, but basically it is a timer for performing error processing when the UNBL signal is no longer input, that is, when a UNBL error occurs. Therefore, no particular explanation will be given during normal operation.

2-d Identification of Continuous Laser-On Next, the operation of the above-mentioned type free flop 10 will be explained.

A video signal is input to the clock terminal of this flip-flop 1o, and the Q output is determined to be "high" at the rising edge of the video signal changing from "low" to "high". Furthermore, in order to make this Q output "low", port P5 of the CPUI is made "low", and the Q output is inverted by the clear input of the flip-flop 10. This flip-flop IO is used to determine whether or not the laser has been turned on continuously for a predetermined period of time based on a video signal.

FIG. 4 is a timing chart explaining the operation of this flip-flop lO.

In the figure, the input to CPU port P8 is a video signal. Here, let's assume that the Bo) Pill input is ``Low''.
In other words, if the laser-on state is detected, the boat P5 outputs 1 pulse, and the boat P4 input Q
Reset output information to "low". Therefore, after the predetermined time has elapsed, by referring to the input of baud P4, it can be determined whether or not the laser was continuously turned on during the predetermined time period.

That is, if the input of baud P4 remains "low", it can be determined that the laser is continuously on; on the other hand, if it changes to "high", it can be determined that the laser is not continuously on. This predetermined time t basically means that the CPUI is A.
If the laser is turned off during A/D conversion, the output voltage of the light receiving element (bin photodiode PD) of the laser 8 will be the A/D conversion time of the CPUI.
If the A/D conversion value is not held until the end of the A/D conversion, it cannot be treated as a correct A/D conversion value.If the laser is turned on by the UNBL signal, the specified time t is guaranteed, but if the laser is turned on by the image information, the specified A/D conversion value is not maintained. The time t cannot be guaranteed, so after processing the A/D conversion, etc., the A/D conversion value or the processing associated with it is determined to be valid or invalid depending on whether the laser was continuously turned on or not. Gain control.

(2-e) Program Control First, program control in such processing will be explained.

This corresponds to 510 in the main routine shown in FIG. 3(a).
3 to 5106 are the relevant parts. In this embodiment, this control is performed after the operation of the La5erA PC is started, that is, when the FLAG-A flag is set, but this is only for -
For example, it may be executed from the time when LagerA PC is started up, or it may be executed from the time when the UNBL signal T
There is no need to distinguish it from RUE timing.

When the FLAG-A flag is set, it is identified in 3102 of FIG. 3(a), and it is determined whether the laser is on or not based on the input from boat P6 (rs193). If the laser is off, this control is executed. finish. on the other hand,
If the laser is on, a clear pulse to reset the flip-flop 10 is output from the boat P5 (S104.
5105), and then executes processing including A/D change 4 and calls APC-TABLE. In addition, APC
- When TABLE is cooled, select and execute one of the APC routines as described above.

As shown by ■ in Fig. 4, if the laser is not turned on continuously for a predetermined time t, the Q output of the flip-flop lO is "high" at the end of the APC routine, so The input of P4 is judged as "high",
It becomes invalid.

On the other hand, as shown by ■ in FIG. 4, when the laser is kept on continuously, the Q output of the flip-flop IO is "low", so the input of the boat P4 is determined to be "low". Validate the results of the APC routine.

In addition, in image information, even if the laser is not on for a predetermined time or longer, scanning of the l line has one UNBL signal in principle, so unless a UNBL error occurs, at least one UNBL signal is required for the scanning of the l line. The execution result of the APC routine is valid.

Although the flip-flop 10 is used in this embodiment, other circuits may be used as long as the same effect can be obtained.Furthermore, an external circuit such as a flip-flop can be used to generate a video signal without using a circuit. is connected to the interrupt terminal of the CPUI, so that an interrupt is generated at the leading edge when the laser is turned on, and when an interrupt occurs, the FLAG-A flag is checked and the board P5 is
It is also possible to output a clearer pulse and call APC-ABLE.

The processing of La5erA PC will be explained below.

(2-f) IDLE Routine First, control for raising the laser to a predetermined light intensity will be explained.

When the power is turned on, initial processing is executed by the main routine shown in FIG. 3(a), and then the process moves to the IDLE routine. Note that this IDLE routine includes A in FIG. 3(d).
Includes execution of the PC-RESET routine.

In this IDLE routine, first, A P C-RES
This APC-R
Since the ESET signal becomes FALSE only during the period from when the LBP executes the print operation to when it ends, the APC-RESET routine is called at this time (SIOI).

As a result, the A P C-RESET in FIG. 3(d)
In the routine, the D output data and R output data are respectively set as rooHJ5400.5401), the outputs of CPU boat P1 and boat P2 are respectively set as roOuJ5402), and the laser drive current i[
Set to 0■A. Furthermore, set the output of boat P3 to “high”
By doing so (S403), the laser on is canceled.

And the flag for Arc-DING ABLE control.
A P C-M with BLE-NO flag as rooHJ
Specify OP (3404), reset the FLAG-A flag) (S405), and return to the main routine 3102.

Next, the main routine checks the FLAG-A flag (5102) and returns to 5100.

Then, the APC-RESET signal becomes TRUE-t'
If so, repeat the above operations.

Note that even if the interrupt routine shown in Figure 3(C) is entered and APC-TABLH is called during APC-RESET, the TABLE-NO flag will be set to rooH.
Since it is J, Figure 3(f) is simply called, and as shown in the figure, it returns without executing anything.
La5erA PC is not performed.

Next, the control device starts rotating the scanner motor, ζ, which will perform the printing operation, for example first. Then, when the rotation of the scanner motor reaches steady rotation, the control device obtains the BD double signal, so the UN
Set the BL signal to TRUE and hold it until you get the BD double signal.

Then, when the UNBL signal reaches RUE, the CPU 1 shifts to the UNBL interrupt operation and executes the interrupt routine shown in FIG.
Since ESET is in progress, there is no effect, and regarding each flag etc.
This is not a problem as it is initialized in the ART routine.
Note that, as described above, the BD double signal is not generated until the laser emits light, so the interrupt routine by the UNBL signal is not called until the laser emits light.

2-g) APC-START Routine The above control device sets the UNBL signal to TRUE and then sets the APC-5TART signal to TRUE. As a result, the light amount control device of this embodiment has AP
The following APC operation is executed to maintain a constant light amount until the C-RESET signal becomes TRtlH again. When the APC-5TART signal is received again, the start-up operation is executed again, and the APC operation is continued again to maintain a constant light amount.

When the APC-5TART signal becomes RUE, a CPUI interrupt occurs at its leading edge, and the AP in Figure 3(e)
Enter the C-START routine.

In this APC-5TART routine, first, threshold data is transferred to the D output data memory (550
0), one of the threshold data is rooHJ, and the other is the current value at which the laser starts emitting light, that is, the data value of the threshold current Ith. That is, this threshold value data is r00+J after power is turned on, but after current is turned on.

If you run La5erAPC even at -degrees, roOH
It will no longer be J. In other words, the second and subsequent La5erA P
The rise of C starts from the data value of threshold current Ith. Note that a method for determining the data value of this threshold current zth will be described later.

Next, clear the R output data and R hold data for the fine adjustment D/A converter, that is, set them to "0ON" (3501.5502), and then clear the R output data and R hold data for the fine adjustment D/A converter.
UNB to know whether an interrupt by NBL signal has been made or not
Reset the L-IN flag (5503), and
Please set the FLAG-A flag to "1" S 504)
, set the TABLE-NO flag to “OIN” (S
505), and further resets the UNBL error timer 8506), and returns to the main routine 8100.

2-h Calling APC-TABLE When APC-5TART is applied in this way, the main routine transitions from the above-mentioned loop as follows.

First, from 5100, the APC-RESET routine (
Step S101) is not executed, and it is determined that the FLAG-A flag is set.Step 5102) and subsequent steps 5103 are executed.
Since it is set to TR, the video signal is also TR.
The current is 11E, and the laser is on. Therefore, the process moves from 5104 to 5106 and returns to 5100.

As a result, until the laser emits light, the FL
Since the AG-A flag is not reset, APC-TABLE is called almost continuously in the main routine cycle at 510B, and the La5er APC is started up.

(2-i Arc-01 routine On the other hand, APC-TABLH is the Ar
c-9TART routine, A shown in FIG. 3(g)
Indicates the PC-Ot screen. This APC-01
The routine executes a comparison operation of only the D output data for the rough adjustment D/A converter 2.

In addition, in the APC-Ot routine, the fine adjustment D/A
Since the R hold data and R output data of the converter 3 are both roOuJ, the laser drive current iL is baud for the coarse adjustment D/A converter 2) P2
Determined by the output data value. Also, the startup method for this rough adjustment D/A converter 2 is as follows: APC-5TART
There are two methods depending on the contents of the threshold data set at 3500 in the routine.

First, a case where the threshold private data is rooHJ will be explained.

First, in step 5106 of the main routine, APC-Ot
When 5600 is called, D output data is output to the output of baud P2 for the coarse adjustment D/A converter 2, and D output data is output to the output of the port Pl for the fine adjustment D/A converter 3. R output data, ie, roOHJ is output. Then, the amount of laser light at these data values is measured using a feedback voltage from a light receiving element (bin photodiode PD) built into the laser 8. In other words, the analog voltage value from the light receiving element is A/D converted (5601), this value is compared with a reference value corresponding to 70% of the desired amount of laser light (S602), and if the measured value is less than 70% , increment the data value in the D output data memory 5603), and check whether the data value has overflowed (S604).
From 5604 to 5606, the laser drive current i[
A process is performed to check whether or not there is a laser error, which will be described later, but normally there is no laser error and the process returns from step 5604. Further, since the A/D conversion value at 5601 is always in the laser on state due to the UNBL signal, it can be determined to be valid without checking.

As described above, steps 5600 to 5604 are executed.

Returning to the main routine, the main routine is called again, so that the laser drive current i[ of the rough adjustment D/A converter 2 is raised almost continuously and every step. As a result, the laser beam is raised to 70% of the desired light intensity in the Arc-01 routine, however, in the APC-01 routine, the laser beam is increased to 0%.
In order to ramp up to ~70%, the timing at which the laser is called will vary from when the laser starts emitting light. This is because the laser drive current i [is gradually increased by the APC-01 routine, so that the laser starts emitting light at a threshold value. When the BD signal reaches the BD signal, the UNBL signal changes from a level signal to a pulse signal. therefore,
The interrupt routine is now called by the UNBL signal, and when this interrupt routine is called, it progresses to 3300.5301 at the first time, and at 5302, FLAG-
From A flag = 1, proceed to 5305.5306, and,
Since the UNBL-IN flag=0, the process advances to 5307 and returns as FLAG-A=0. Then, in the main routine, the FLAG-A flag is checked at 5102 and determined to be "0", and the process returns to 5100. That is, 310
0→5102→3100→... will be repeated, and the APC-TABLE call at 5106 will no longer be made.

Next, when the second interrupt routine is entered by the UNBL signal, it progresses to 5300, 5301, 5302, and then FL
Proceed to 3303 from AG-A flag = 0, UNBL-I
Set the N flag to rlJ, and at 5304
will call TABLE, and 530
The process proceeds to 5.5306 and returns because the UNBL-IN flag is 1.

Note that this UNBL-IN flag is the same as the above APC-ST.
The FLAG-A flag is reset in 5307 because it is only reset in the ART routine.
9 Only for TART routine. Therefore, after this, the FLAG-A flag remains reset until the startup of the La5erA PC is completed, and the APC-DABLE call (S30
4) is executed.

From the above, the timing to start up the La5erA PC is to start up the laser drive current i[ almost continuously until the laser emits light, and then start up the laser drive current i[ after the laser emits light].
It is raised only when the NBL signal is TRUE, that is, in the non-drum area. Therefore, this AP
The C start-up operation is performed without irradiating the photosensitive drum during LBP with laser light.

Also, in this way, in the Arc-Of series,
Once the laser starts emitting light, the timing of the call will vary, but the value of the rough adjustment D/A converter 2 will gradually increase. Note that if the UNBL signal is TRUE, the laser will be on during that period. Because of this, U
Even in the NBL interrupt, the feedback voltage from the light receiving element can be obtained by simply calling APC-TABLE. Furthermore, since the A/D conversion value processing ends while the UNBL signal is TRUE, it can be determined that the data is valid without checking.

Then, in the Arc-01 routine, when the laser beam reaches 70% or more of the desired light amount (S 602), the process moves to 5607, and processing for the UNBL error is performed (S 6
07 to 3609), since no UNBL error occurs during normal operation, this will be explained later.

Next, the D output data determined by the APC-01 routine is stored in the D hold data memory (3610), and the APC
-02 Execute processing to relay to routine (561
1).

(2-j APC-02 routine Next, the APC-T
When the APC-02 routine is entered by the ABLH call, D output data and R output data are first output from the boat P2 and boat PI of the CPUI (S700).
After 5701, the same processing as the APC-01 routine is performed, except that the comparison data value is 80% of the desired amount of laser light. In addition, in the APC-01 routine, the data to each D/A converter was returned from 5604 as D output data and R output data, but in the Arc-02 routine, each output data was changed to D hold data and R hold data. Switch to data and return (3708).

That is, in the APC-02 routine, during the TRUE period of the UNBL signal when this routine is called, the laser is emitted with D output data, a comparison calculation is performed, and the laser light is brought up to 80% of the desired light amount. Shikashi, UN
When the BL signal becomes FALSE and the laser scans the photosensitive drum, the laser beam can be emitted with the D hold data and R hold data values.

At this stage, Arc-RDY has not been set, so the laser will not emit light when scanning the photoreceptor drum area. However, if it does, the laser light will be at 70% of the desired light amount. . The proper use of output data and hold data will be explained in the data overflow/underflow processing described later.

Then, the coarse adjustment D/A converter 2 is started up every step by one APC-02 routine call using the D output data, and the laser drive current i[ is increased to 80% or more of the desired light amount (3702). , executes processing to be relayed to the APC-03 routine (S707).

(2-k) Arc-03 routine The APC-03 routine compares the measured value and the 80% value (
S802) and D output data decrement operation (
S803) is performed, and other processing is performed by APC-0.
2 routine. In other words, in the APC-03 routine, in order to converge the D output data that exceeded the 80% value of the desired light amount in the APC-02 routine to a state as close as possible to the desired light amount 80% value, the 80% value is
It is checked whether it is less than the % value, and if it is 80% or more, the D output data is decremented in step 5803. In this way, the D output data exceeds the 80% value and then is reduced to less than the 80% value, so it converges to a value extremely close to 80% and slightly lower than the 80% value (hereinafter referred to as , this is called the 80% convergence value).

On the other hand, in the APC-03 routine, APC-02
Similar to the routine, comparison calculations are performed using D output data, and other light emission value data is used as D hold data.

Then, when the 80% convergence value is determined, the data value of the coarse adjustment D/A converter 2 is determined, and processing is performed to relay it to the APC-04 routine (3807).
Even if the data value of the /A converter 2 is determined, it is simply stored in the D output data, and the D hold data remains as before. In other words, if the threshold trust data is started from roooJ, the D hold data is 70% of the desired light amount.
The value remains the same.

2-Sentence Arc-04 Routine Next, moving to the Arc-04 routine, the D output data and R output data are output to port P2 and baud) PI to determine the laser drive current i[ (5900), that is, The laser beam will start from a convergence value of 80% of the desired amount of light. Also in the APC-04 routine, Ar
The APC-04 routine performs the same processing as the c-02 routine, but the APC-04 routine uses the measured value and the desired light amount.
A comparison is made using the % value (=desired light amount) as a standard (590
2), and also performs an operation to increment the R output data for the fine adjustment D/A converter 3 (5903);
That is, up to 80% of the desired amount of light is started using the D output data of the coarse adjustment D/A converter 2, and the remaining 20% is started using the R output data of the fine adjustment D/A converter 3.

Then, when it reaches 100% or more, Arc-RDY processing is performed (3907), that is, when it becomes APC-RDY, printing becomes possible and the laser blinks according to the image information. Then, FLAG-Any lag is set to indicate that the startup of the La5erA PC is completed, and the D output data and R
Copy (store) the output data to the D hold data and R hold data, respectively, and determine the data value. Then, in 5909, move to the APC-05 routine with t'JL+', so that the value becomes 100% convergence. Fine adjustment D/A
The data value of converter 3 is controlled. In addition, APC-
Even in the 04 routine, when returning, always return 59.
10, the fine adjustment D/A converter 3 is controlled by the R hold data, and the coarse adjustment D/A converter 2 is controlled by the D hold data.

The above is the method for starting up the La5er A PC when the D output data is rooHJ at the time of the A PC-5TART (when the laser drive current i1 is OmA).

2-m threshold Start-up from ILh, then A
At the time of PC-5TART, the data value is the threshold current Ith
The following describes how to start up LagerA PC when starting from . Note that the operation of each routine is the same as described above, and a description thereof will be omitted.

APC-0 by the APC-5TART routine.
When the 1st routine starts from the threshold current Ith, the Arc-01 routine is called by the first main routine after the APC-5TART routine, and in that 5soo, the D output data is changed to the rough adjustment D/
By outputting to port P2 for A converter 2, instantaneous laser 8 will emit light. As a result, the BD signal is generated, and the UNBL signal changes from a level signal to a pulse signal. Therefore, when starting up the La5er A PC, laser light is emitted from the beginning, and at the same time, the A PC-TABLE call from the main routine is also started.
APC-T by interrupt routine by NBL signal
ABLE call (S304), that is, APC-
In the 01 routine, the laser drive current i[, which had been gradually rising until laser emission, rises rapidly, and the time is shortened accordingly.

The above is the method for starting up the La5erA PC in this embodiment. Note that in this example, La5erA P
Although the start-up of C was set to 100% of the desired light amount, there is no particular limitation.
In order to speed up the start-up of C, we have also explained how to start up from the threshold current ILh.
The data for coarse adjustment and the data for fine adjustment may be increased/decreased in units of several steps, although the data for coarse adjustment and the data for fine adjustment are increased/decreased in steps.

However, according to this embodiment, when the La5erA PC is started up, the laser drive current i1 is maintained until the laser emits light.
is raised almost continuously, and when this reaches the threshold current Ith and the laser 8 starts emitting light, the La5erA P is activated only when the UNBL signal outside the drum area is TRUE.
We will be launching C. Therefore, this L
The photoreceptor drum during BP is not irradiated with the laser, and the amount of light can be increased to a desired level.

Note that from the time the laser drive current i reaches the threshold current Ith to the time it switches to the interrupt routine by the UNBL signal, the laser irradiation is performed for a total of several lines due to an error of at most one line or variations in the BD generation circuit. However, since the amount of laser light is near the threshold value, this does not pose a problem because the setting is such that toner does not adhere to the photoreceptor drum at that small amount of light.

2-nUNBL Error It should be noted that the UNBL signal is indispensable in the startup method of the La5erA PC in this embodiment.

However, as mentioned above, the UNBL signal is closely related to the BD signal, and the UNBL signal may not be generated or may not be generated due to various factors such as the position of the BD generation circuit, laser, optical system, and installation. However, it may stop occurring midway through. Therefore, in this example,
The following error processing is performed for such UNBL errors.

First, a UNBL error when the UNBL signal is not input as a normal pulse will be explained.

The causes of this UNBL error can be roughly divided into two types: when the laser does not emit light, and when there are other causes. The former will be discussed later in the explanation of the laser lifespan, and here we will discuss the latter case where the UNBL signal does not become a normal pulse even though the laser is emitting light.

As mentioned above, in this embodiment, the check is performed when the laser beam reaches 70% of the desired light amount (see Fig. 3).
5607 to 5609), that is, if the laser itself does not emit enough light even though the laser drive current I[ is started up in the Arc-01 routine, 5604 to
At step 5606, it is determined that there is a failure in laser emission (hereinafter referred to as laser error), but on the contrary, after it is determined at step 5602 that the laser emission has reached 70% of the desired amount of light, the UNBL-IN flag is set at step 5607. I'll have to check it out. This flag is set to A P as described above.
It is reset to “0” at C-5TART, and UN
It is set after being confirmed twice or more in the interrupt routine using the BL signal. In other words, if the UNBL signal is not generated even when the laser light reaches 70% of the desired light amount, it can be determined that the UNBL signal itself is not a normal pulse even though laser light is being emitted. Therefore, 3607
If the UNBL-IN flag is determined to be "0" in 8608, the process proceeds to steps 5608 and 5609 as a UNBL error. In 8608, the UNBL-IN flag is set and a timer for UNBL error processing is set for a predetermined period of time. Set the data and start it. And 560
9, it is stored that a UNBL error has occurred.

Note that the UNBL error processing after processing in 8608 is the same as the UNBL error processing when no interruption is caused by the UNBL signal, which will be described later, and therefore the description thereof will be omitted here.

In addition, in 5609, only the occurrence of a UNBL error is memorized, but La5erA PC operation may be interrupted; however, in the case of LBP, BD
Like an error, even if a synchronization failure occurs and the error occurs for a certain period of time, it may eventually recover and the BD error is automatically canceled without being determined to be a BD failure, so in this embodiment,
We have decided to perform UNBL error handling that allows La5erA PC operation to continue without interruption.

In addition, the above-mentioned UNBL error judgment criterion is 7 of the desired light amount.
Although the value is set to 0%, it is not particularly limited as long as it can be determined whether or not the UNBL signal is being input as a pulse even though it has been confirmed that the laser beam is being emitted.

Next, UNBL error processing will be described in which the UNBL signal returns to a level signal even though the UNBL signal becomes a pulse input, such as in the case of a BD error, and an interrupt by the UNBL signal is no longer generated.

In the case of this UNBL error, since the interrupt routine by the UNBL signal has already been executed, the setting of the UNBL-IN flag and the setting and starting of the timer in 5608 described above have been executed. Therefore, even if the interrupt routine is not executed by the UNBL signal, an interrupt is generated by the timer. Furthermore, U
When the NBL signal returns, the timer is reset in step 5300, so no interrupt is generated by this timer, and automatic recovery becomes possible.

Also, in step 8305 of the interrupt routine, a timer is set and started, so the next time an interrupt occurs, it will start when the timer times up or when the U
Either by the NBL signal. therefore,
What is the timer setting time?

It must be at least longer than the period of the UNBL signal. In other words, if it is shorter than the period of the UNBL signal, it will not be possible to start up outside the drum area.
When the L signal is a normal pulse, the interrupt routine must be called by the UNBL signal.

As mentioned above, even if a UNBL error occurs.

By making it possible to call an interrupt routine using a timer instead of the UNBL signal, interruption of La5er A PC operation due to UNBL errors is eliminated. Note that although this UNBL error processing uses a timer, it is not limited to a timer in particular, as it only needs to have the same function as the timer in this embodiment.

The above is the U that occurs during startup of La5erA PC.
This is processing for NBL errors.

Next, La5erA PC starts up and APC-R
The UNBL error handling that occurs in DYi will be described.

First, when it becomes APC-RDY and the FLAG-A flag is set, APC-TABLH is not called at 5304 in the interrupt routine of FIG. 3(C), but is called at 5106 of the main routine, as described above. Ru.

That is, when a UNBL error occurs, the UNBL signal becomes a level signal and the laser is turned on, so that the predetermined time is exceeded and the processed data of La5erAPC is also determined to be valid. Therefore, after launching the La5erA PC, the FLAG-A flag is set, so the UN
When a BL error occurs, APC-TABLE is continuously called in step 5106 of the main routine, so the amount of laser light is always corrected. Although the details will be described later, after launching La5erA PC (7), FL
The AG-A flag may be reset. In this case, the U
Similar to NBL errors, AP C
-Call TABLE to correct the laser light intensity.

Next, a description will be given of laser errors that occur when the laser itself deteriorates over its lifespan and is no longer able to emit laser light to the desired amount of light, or when the laser itself is damaged and no longer emits laser light. In this case, La5erA is generally considered to be the laser life.
The PC operation is interrupted and the APC-RESET state is entered.

First, laser error processing will be explained.

Basically, this laser error is determined to be an error when each D/A converter 2 and 3 cannot obtain a desired amount of light and each data value overflows. In other words, regarding the rough adjustment D/A converter 2,
When the data overflows, the laser drive current i1 becomes approximately 127 .mu.A. Therefore, APC-01-03 calculated by coarse adjustment D/A converter 2
Each routine executes an overflow/underflow check to determine the lifespan (S
604.5704.3804), and when it is determined that the laser has reached the end of its lifespan, it calls the APC-RESET routine to interrupt the La5er APC operation,
The laser drive current i1 is also cleared to OpengA. The fine adjustment D/A converter 3 is checked in step 8904 of the Arc-04 routine, and if it is determined that a laser error has occurred, it performs the same processing as the coarse adjustment D/A converter. In the case of D/A converter 3, the APC-
No error check is performed in the 05 routine.The reason is that when the laser is used for a long time, the laser light intensity decreases due to thermal characteristics, etc., so it is necessary to make adjustments using the fine adjustment/A converter 3.At this time, overflow or underflow occurs. However, this is because the amount of laser light cannot be adjusted. Note that this processing will be described later.

On the other hand, in the Arc-04 routine, even if the laser is in the worst condition, the fine adjustment D/A converter 3 can start up from the 80% convergence value to the desired light amount without overflowing, as shown by the formula below. Therefore, we perform laser error detection.

(4.5mW x 20%) 10.1mW/s+A
=9mA9PurchaseA70.05 layer AI station, bu = 18
0 (=84n) steps Regarding the numerical values of the above formula,
This will be explained in the laser life notice process below.

(2-o) Laser lifespan notice Next, the laser life advance notice process will be explained.

This is because when the laser reaches the end of its lifespan, LBP will be interrupted under any circumstances, so by giving advance notice of the laser's lifespan before it is interrupted, major troubles can be prevented.

This embodiment has a memory (threshold data memory) for storing the data value of the current (threshold current Ith) at which the laser starts to emit light, and a coarse adjustment D for when the laser starts to emit light. /Stores the data value of A converter 2. After that, the 80% convergence value is determined by the coarse adjustment D/A converter 2, and FLAG- indicates that the desired light amount has been reached.
The data value (80% convergence value) of the D output data memory after the A flag is set is subtracted by the data value of the threshold data memory. Then, the laser life forecast is determined based on the amount of difference.

5308 to 53 in the interrupt routine of FIG. 3(C)
12 is a sequence for predicting the laser lifespan.

First, when power is turned on, the RAM containing the threshold trust data memory is cleared with predetermined initials roO++
It becomes J.

Then, when the La5erA PC is executed for the first time after the power is turned on, when the UNBL signal becomes continuously TRUE, -
Shift to the claw side insertion routine. And 5301 to 5
Moving on to 308, at this stage the D output data is roohJ
Therefore, 5
Moving from 309 to 5302, and La5e
When rAPC starts to start up, the laser starts emitting light, and the interrupt routine is called again by the UNBL signal. Then, the process moves from 3301 to 5308, and the data value of the D output data when the laser starts emitting light (the data value of the threshold current 1th of that laser) is stored in the threshold trust data memory, and from this point on, the power supply is turned off. Latched until turned off.

That is, in this embodiment, the first data value of the laser threshold current Ith obtained after the power is turned on is stored in the threshold credit data memory. Note that when a UNBL error or a laser error occurs, this threshold trust data memory may be cleared to roo, J, and the data after power-on does not necessarily have to be stored.

Next, in 8308, once the threshold trust data is determined, the FLAG-A flag indicating that the startup of the La5erA PC has been completed is checked (5309).
, and 53 until the FLAG-A flag is set.
Move to 02. Then, when the FLAG-A flag is set, the process moves from 5309 to 3310, and calculations for predicting the lifespan are executed. This operation subtracts the content of the threshold trust data from the content of the D output data. In other words, when the FLAG-A flag is set, the D output data has an 80% convergence value, so (80% convergence Ki
)−(L threshold current) is calculated. Then, in step 5311, it is checked whether the differential current data value is greater than or equal to the preview data value. As a result,
At 5312, it is determined whether or not to execute a lifespan advance warning process such as displaying or warning of laser lifespan, and the process returns to 5302. In addition, the judgment of this laser life is always based on UNB once the La5erA PC starts up.
Since it is executed as long as the L signal is generated, the result is obtained with the latest 80% convergence value each time, so even if the laser gradually deteriorates, it can always be detected.

Next, a method of setting a differential current value that is determined to be the laser lifetime will be described.

FIG. 5 is a schematic diagram showing the characteristics of a semiconductor laser.

Normally, a semiconductor laser has a current-light amount characteristic (hereinafter referred to as an i-L curve) as shown by the solid line in FIG. Current value at which the laser starts emitting light (threshold current Ith)
is about 20 to 60 mA tear, and the slope efficiency η is the laser light amount and current ratio (inclination of i-L curve) tear, 0
．． It is about 1-0.6 layer w1 layer A.

Further, normally, the threshold current rth is about 40 mA, and the slope efficiency η fluctuates around about 0.3 mW1 mA. Then, as the laser deteriorates,
In the i-L curve, as shown by the dotted line in FIG. 5, the threshold current Ith increases and the slope efficiency η decreases. In other words, in order to obtain the same amount of light, more current must be applied. Then, the condition of the laser gradually deteriorates, and eventually a predetermined amount of light can no longer be obtained, and the laser no longer emits light.

Therefore, in this embodiment, the life prediction is determined when the slope efficiency η falls below a predetermined value. This value is calculated as follows.

(A) Desired amount of light of the laser...Considering 10% of the thermal characteristics, the maximum for the rating 5*w is 5 ■-X0.9 = 4.5 (B) 80% convergence value and threshold Calculate with current. Therefore, 80%
The maximum convergence value is.

4.5 Rin - Xo, 8 = 3.8 - (C) From the minimum value of slope efficiency to the threshold current value, the upper limit of the differential current up to the 80% convergence value is 3.6 mW70. 1 mW/mA = 38mA
(D) When converted to the data value of the coarse adjustment D/A converter, it is 0.5 ■A/step 2 per step, so 36 ■A10.5 ■A/step = 72 (= 48
) Step Therefore, the differential current value determined in this program is 36 mA or more, and the set value of the data value level of the rough adjustment D/A converter is 48n or more.

That is, if the result of subtraction in (A), (B), and (C) is 488 or more, it is determined that the laser life is predicted in (A), (B), and (D). It should be noted that a margin may be added to this lifespan notice setting value, such as 50H1608, that is,
As long as 48H can be processed as a guideline for predicting the end of life, there is no specific fixed limit to the set value.

Also, even with the maximum slope efficiency (3.8 adl 0.8 s+n/mA) /
0.5 mA/X? tb=12(=O1ll:n)
However, as the deterioration progresses, it will eventually become 0,
Since the value at the slope efficiency of 1 mW/■A is also lower, there is no need to change the setting value for each laser, and of course it is possible to change the setting value for each laser.

However, even if the end of life is announced, the slope efficiency will only decrease and it will not be the reason why the desired amount of light cannot be obtained. For example, troubles due to laser failure can be avoided.

In this embodiment, the life prediction was obtained using the difference current between the 80% convergence value and the threshold current, but any point may be used as long as the difference current is used.

In addition, regarding UNBL errors, laser errors and lifespans, laser lifespan notices, etc. mentioned above, please refer to the following La5.
It continues to be performed even when the erA PC is in operation.

(2-) In the operation method after Arc-RDY, the La5er A PC operation after APC-RDY will be explained.

As described above, when the desired light amount is reached by the Arc-04 routine and Arc-RDY is reached, the process is relayed to the APC-05 routine. In this Arc-05 routine, the data value of the fine adjustment D/A converter 3 is adjusted by incrementing or decrementing according to the fluctuation of the laser so that the desired light amount is always obtained (hereinafter, this adjustment value is referred to as 100). % convergence value), that is, Arc-05
In the routine, the fine adjustment data value is corrected to a 100% convergence value in order to maintain the desired light amount. Also,
This 100% convergence value correction is intentionally performed when executing La5er APC, since APC-TABLE is called and executed when the image signal continues for more than a predetermined time or when the UNBL signal is TRUE. There is no need to turn on the laser.

Note that when the fine adjustment D/A converter 3 executes a comparison operation to maintain a 100% convergence value, for example, if La5erA P C is performed for a long time, the above i-L The curve drifts and the laser light intensity gradually decreases. As a result, the laser drive current i1 will increase, but if the light intensity decreases by 10% or 20% due to self-heating, the fine adjustment D
/A converter 3 alone cannot cope with this problem. Therefore, in such a case, it is necessary to perform re-correction including the rough adjustment D/A converter 2.

2- Up/Down is there, and here, before explaining the Arc-05 routine, we will explain the correction process including the coarse adjustment D/A converter 2 when the data value of the fine adjustment D/A converter 3 overflows or underflows. explain. Note that this process is hereinafter referred to as carry/down process of the fine adjustment D/A converter 3.

In the Arc-05 routine as well, it is the R output data that performs the comparison operation. Then, when the APC-05 routine ends, R hold data is output to the fine adjustment D/A converter 3.

However, after the comparison operation, it is determined whether or not to transfer the R output data to R bold data. After the comparison operation, it is determined whether the data value of the R output data has become r00++J or not, and a determination is made as to whether to execute the carry/down process.

If it is determined that the carry/fall has not been executed, continue with A.
Continue running the rc-05 routine. However, if a carry/fall (overflow/underflow) is determined, the FLAG-A flag is reset to rQl and T
ABLH-NO is set as r02HJ to instruct the APC-02 routine and relay to it. At this time, coarse adjustment D/
The data value of the A converter 2 is the 80% convergence value stored in the Arc-04 routine, and the data value of the fine adjustment D/A converter 3 is the R hold data before carrying up/down with the R output data. It is. Note that the R output data is determined as a result of calculation, so it is roonJ, and the R hold data is.

Since this is the state before the calculation of R output data, rFFnJ
Or it should be roIHJ.

Next, carry/down processing will be explained while explaining how to use these R output data, R hold data, D output data, and D hold data.

First, in the APC-5TART routine, R output data and D output data are cleared to roonJ.

Also, nothing is done to the D hold data, and the threshold trust data is loaded into the D output data memory.

Then, in the Arc-01 routine, until the laser 8 starts emitting light, the UN
While the UNBL signal is TRUE in the BL signal cycle, D
The coarse adjustment D/A converter 2 is started up using only the output data until the desired light amount is reached. On the other hand, R output data and R
Nothing is done with the hold data and D hold data, but when the APC-01 routine is relayed to the APC-02 routine, the APC-01 routine loads the data value of the D output data memory into the D hold data memory. Therefore, R output data = R hold data = 0
0+, D output data 20 hold data = desired light amount 7
The data will be 0% value.

Next, while the APC-02 routine is being executed, the laser drive current i determined by the R output data and the D output data is used to drive the laser 8.
will emit light, and we will compare this. Then, while incrementing the D output data,
% or more, the APC-02 routine is executed during the ↑RUE period of the UNBL signal. Then, when the execution of the Arc-02 routine ends, the laser drive current is switched to the laser drive current 11 determined by the R hold data and the D hold data. In other words, the laser drive current determined by the R-hold data and D-hold data when the laser beam for raster scanning is determined by the R-hold data and D-hold data in the drum area, and by the R-output data and D-output data during the TRUE period of the UNBL signal outside the drum area. The laser emits light at i[. In addition, this APC-02
In the routine, neither the R hold data nor the D hold data is done and the state when the Arc-02 routine is entered is maintained.

Next, when the conditions in the Arc-02 routine are satisfied,
Relayed to APC-03 routine. Arc-03
The routine is similar to the APC-02 routine, although the data value conditions for the D output data are different.

Next, in the APC-04 routine, the TR of the UNBL signal is
The APC-04 routine is executed during the UE period, and the amount of laser light is determined in the drum area using R hold data and D hold data. Also, while the APC-04 routine is being executed, the laser is emitted using the R output data and D output data.
, R output data is incremented to reach the desired light intensity, and when the conditions in the Arc-04 routine are satisfied, it is relayed to the APC-05 routine, but at this time the data value of the D output data memory is is loaded into the D hold data memory, and the data value of the R output data memory is loaded into the R hold data memory. Therefore, APC-02 to APC-04 routines are APC
During the -TABLH call, the amount of laser light in the drum area is updated upon completion of the APC-04 routine.

Therefore, in the Arc-05 routine overflow/
If an underflow occurs, the data value immediately before the overflow/underflow is stored in the R hold data and D hold data as carry/down processing. Then, return to the APC-02 routine and set the laser light intensity again, but APC-02 to APC-04
In the routine, nothing is done with R hold data or D hold data, and the desired light amount is raised using D output data and R output data. Then, when the APC-0 rises, the D hold data and R hold data are updated, and the APC-0
5 routine, and correction is executed to protect the 100% convergence value.

On the other hand, the call timing of APC-TABLH is
During carry/down processing, FLAG-A flag is rQJ
is called by the interrupt routine, and restarting in the APC-02 to APC-04 routines is performed only during the TRtlE period of the UNBL signal, and when the restarting is completed, FLAG-A is reset in the Arc-04 routine.
Once the flag is set in rlJ, it will be called again by the main routine.

As described above, in the Arc-05 routine, the fine adjustment D
If the data value overflows/underflows and becomes impossible to correct while performing 100% convergence value correction using the /A converter 3, the data value may overflow/underflow and become impossible to correct, in the drum area (in the image printing area) during the period when the laser beam is raster scanned. latches the final data value before the carry/fall, and enables the laser to emit light with the laser drive current IC determined by the data value (R hold data and D hold data) until the laser light rises again. Enable printing. Then, outside the drum area during raster scanning of the laser beam (during the period when the UNBL signal is RUE), the D output data and R output data are used to determine the 80% convergence value or the corresponding data value for the desired light amount. In other words, when the fine adjustment data overflows/underflows, the previously determined 80% convergence value data deviates from the actual desired light intensity of 80% i1. Therefore, by resetting it, 100% convergence value correction can be performed.

By making it possible to execute one-digit up/down processing in this way, the fine adjustment D/A converter 3 can
Even if it becomes impossible to correct the 0% convergence value, the reset can be carried out in a non-printing area (outside the drum area) without interrupting the printing operation.

Therefore, with the La5erA PC of this embodiment, the light amount control for 100% convergence value is possible semi-permanently, that is, until the laser lifespan, so a predetermined light amount can be continuously maintained in the printing area. .

Note that the drift in the amount of laser light that is latched and output during resetting is only for a very short period of time, so it is not a particular problem.The reason is that since the start-up is from approximately 80%, the coarse adjustment D/A converter 2 Now, you can set it in a few steps, and also use the fine adjustment D/A to start up the remaining 20% of the light intensity.
With converter 3, at most 180 steps, 2 in total
Just under 00 steps is enough. Since this is increased once every l step to the IUNBL signal (l line), it can be completed in 200 lines.

Therefore, even if the LBP has a resolution of 240 dpi, it will be completed in about 20 seconds, and since this time is within 1 second even in a low-speed LBP, there will be almost no effect of thermal drift.

(2-r) Arc-05 Routine Next, the APC-05 routine will be explained. The Arc-05 routine of this embodiment controls the amount of laser light to maintain it at a level slightly higher than the desired amount of light (hereinafter, this level will be referred to as the 100% convergence value).

When this Arc-05 routine is instructed by an APC-TABLE call, it first compares the R output data and the R hold data (31000), and if they are equal, there is no comparison operation and the process goes to 31012. /A PC-04 routine inputs D hold data (80%
convergence value) is output. Further, in this APC-05 routine, the D hold data and D output data for the rough adjustment D/A converter 2 remain unchanged.

Next, by outputting the R hold data to the boat P2 (Stool), the feedback voltage when the laser 8 is turned on by the laser drive current iL determined by the D hold data and the R output data is A/D converted.
02), compare it with the desired light amount data (31003), and if the result is less than 100% value, increment the R output data 51004), and conversely, if it is more than 100% value, decrement the R output data (51005), and this operation Check the result for overflow/underflow (31006).

Here, if the calculation result is roOuJ, then FL
Reset the AG-A flag SIO10), Ar
Relay to c-02 routine (51011
), R to boat Pl for fine adjustment D/A converter 3
Output the hold data (51009) and return. Then, from the next APC-TABLE call, the carry/down process starts to be executed as described above. On the other hand, if it is determined in 31006 that it is not roonJ, the process proceeds to 51007, and by checking the boat's 24-person power, it is determined whether or not the laser has been turned on continuously from the time the APC-05 routine was entered until the present time. and determines whether the comparison operation is valid or invalid. If it is determined to be invalid, the R hold data is loaded into the R output data memory, the R output data result is canceled (5tooa), and the data value of the fine adjustment D/A converter 3 is returned as the R hold data (51009).
On the other hand, if it is determined to be valid, the R output data returns the data value of the fine adjustment D/A converter 3 as the R hold data with the content of the above comparison calculation result (S1009
).

In addition, if it is determined in 31000 that the R output data and the R hold data are not equal, it means that there is a comparison calculation data result that has not been updated, and the R hold data that determines the current laser light amount and the R output data, which is the data after the comparison operation (S I 012), and if the R output data is larger, it is determined that the R hold data has been incremented as a result of the comparison operation. do. In other words, it is determined that the current laser light intensity is lower than the desired light intensity, and until the UNBL signal is input (S1013
), when the UNBL signal is present, the data is updated to the value of the R output data (51014) and output to the baud Ill for the fine adjustment D/A converter 3 (51009).On the other hand, when the R output data is smaller ( S1012), as a result of the comparison calculation, it is determined that the value of the R hold data has been decremented. In other words, it is determined that the current laser light intensity is at a higher level than the desired light intensity, so data latching with R hold data continues in 51009 until the UNBL signal is input (Sto 15), and the UNBL signal is input. Then, the R output data should be output to the baud) PI for the fine adjustment D/A converter 3 (51016), and the D
Comparatively measure the laser light intensity determined by the hold data and R output data (S l 017.5IO18), and if the result is less than the desired light intensity (less than 100%), the R hold data that determines the current laser light intensity In this case, the level is higher than the desired amount of light, but it is determined that the R output data obtained by l steps down is at a level lower than the desired amount of light. In other words, this is determined to be a 100% convergence value, and in order to cancel the R output data, the R hold data is loaded into the R output data (S1019), and the current light amount data is the R hold until the UNBL signal of the next line. Continuing and latching the data (51009), conversely, if the comparison measurement result at 51017.51018 is more than the desired light amount (100% or more), then in the R hold data that determines the current laser light amount, Even if the R output data is at a level higher than the desired light amount and is further stepped down by one step, it is determined that the level is higher than the desired light amount. In other words, R
In the hold data, it is determined that the light intensity is higher than the desired light intensity even if it is lower than the desired light intensity by l steps, so the R hold data is updated to the value of the R output data, and the UNBL signal of the next line is latched (S1020 ), since it is impossible for the laser light intensity to suddenly increase and then decrease after a few lines, other than in an error mode such as a laser failure, the light intensity stabilizes at 100% convergence value as shown in Figure 6. controlled.

As described above, in this embodiment, the 100% convergence value is determined by the laser being turned on continuously for a predetermined time or longer, and when the comparison calculation result becomes valid, the next UNBL signal is used to obtain the data value (R output data content) in the comparison calculation. ) to perform comparative measurements. As a result, it is determined whether to update to the comparison calculation data (R output data) or continue with the previous data (R hold data). This allows the data to be latched and updated on a line period to a level slightly above the desired amount of light (
The amount of laser light will settle down at 100% convergence value). Normally, if the laser beam does not drift, Figure 6 (1)
).

Further, even if the value decreases due to thermal drift, it is corrected as shown in FIG. 6(2). Furthermore, even if there is a large deviation from the desired amount of light, as shown in Figure 6 (3) or (4),
It is corrected in several lines and becomes a 100% convergence value. Note that the time required for the light intensity to decrease due to thermal drift is usually 10
Because it is sufficiently slower than the time for 0% convergence value correction, Fig. 6 (1)
Alternatively, the operation shown in (2) alone can be sufficient for correction. In other words, the drift of the laser beam over a long period of time is corrected little by little in short periods.

Next, in this embodiment, even if the laser is not turned on by an image signal for a predetermined period of time or more, UNBL is always performed once per line.
Comparison operations are performed on the signals. However, since the comparison measurement in this case is performed using the next UNBL signal, one step of the fine adjustment D/A converter 3 is corrected in two lines. Even when compared with the case where a comparison is made using the UNBL signal,
Even if thermal drift or the like occurs when performing the 00% convergence value correction, it does not pose any problem.

As described above, in this embodiment, even if the laser is not turned on for La5erA PC, the U
The amount of light can be stabilized by turning on the laser based on the NBL signal or the image writing signal in the drum area.

Then, this light amount stabilizing means raises the light amount to a desired amount using the UNBL signal, and in order to maintain the desired amount of light, compares and measures the comparison calculation result executed on the previous line again using the UNBL signal of that line and updates it. Decide whether or not. As a result, it converges to a 100% convergence value in one line period or several line periods. And this is always repeatedly controlled.

On the other hand, various error judgment processes are executed, such as lifespan judgment or lifespan prediction judgment based on laser errors, or UNBL error judgment, to prevent La5erA PC operation from becoming disabled, and to prevent the fine adjustment D/A converter 3 from carrying over or
The light amount stabilization correction of La5er APC can be executed by the lowering process.

Note that in this embodiment, the data resulting from the comparison operation (R output data content) is the data before the comparison operation (R hold data).
If it is larger than , the desired light amount has decreased, and the data is updated without comparative measurement. However, irrespective of the magnitude of the data in the comparison calculation, a -temporal comparison measurement may be performed to determine whether or not to update the data.

Next, a second embodiment of the laser life prediction will be described.

In the first embodiment described above, the laser life prediction was determined based on the difference current data between the threshold current data obtained by the first La5er A PC and the 80% convergence value, but in this embodiment, the threshold current data The determination is made based on the current amount (absolute value) of the rough adjustment D/A converter 2. Therefore, in the first embodiment, during the interrupt routine shown in FIG.
301.5308 to 5312 are no longer necessary. Instead of this, the Arc-03 routine of FIG. 3(i) is modified as shown in FIG. That is, in this APC-03 routine, when the laser light intensity is increased to the 80% convergence value by the coarse adjustment D/A converter 2, T
The process moves to aO2 and processing is performed to relay to the APC-04 routine.

After this, T811 and T812 will be used to predict the laser lifespan.
is added and moves on to TaO2. The subsequent steps are similar to those in the first embodiment.

At T811, the 80% convergence value determined by the D output data is compared with the set value rc8nJ, and if the 80% convergence value is greater than or equal to the set value, the process proceeds to T812 and executes the desired laser life warning process. , move to 780g. On the other hand, if T811 is less than the set value, the process moves to TaO2, so it is not determined that the laser life is predicted.

Next, the setting values used for laser life prediction will be explained.

In the coarse adjustment D/A converter 2, the data value is rc8.
+J means that 0.5mA/step XCXC8n=1O0. In other words, when the laser drive current i[ to satisfy the 80% convergence value of the laser beam becomes equal to or greater than 100.A, it is treated as a warning of laser life. As described in the first embodiment, even in the worst case, the laser drive current to satisfy the 80% convergence value of the laser beam is 80% after the threshold current.
It is 36 ■A up to the 0% convergence value. Add the threshold current to this. Note that this threshold current 1th also varies depending on the laser, like the slope efficiency, and is within the range of 20 to 60 mA. Therefore, threshold current I thu^X) + 36a+A= 9
It becomes 6mA. Then, with some margin added, 10
It becomes 0+mA. Note that, depending on the laser, it reaches 80% convergence 4 (+) in several tens of layers A, but if it deteriorates, the life expectancy can always be determined at this mA line.

In this example, the laser life prediction was determined based on the absolute current amount at the 80% convergence value of the laser beam, but based on the same idea, it may be checked based on the lOO% convergence value. D/ for fine-tuning data value comparison between two
The data value of the A converter 3 may be used.Furthermore, the setting value may not be fixed as in the above embodiment, but may be configured to be variable.For example, in the second embodiment,
It may be variably set to a value of laser threshold current Ith+40 mA.

3-b Third - Next, a third example of the above-mentioned laser life prediction will be described.

In this example, a laser unit having a laser 8 includes:
A data code instruction means consisting of several bits is provided so that the CPU can read data coded according to the laser characteristics.If this code data indicates the initial threshold current Ith of the laser, In the first embodiment, the difference current from the 80% convergence value may be calculated, or the difference current from the current threshold data may be calculated. Furthermore, in the second embodiment, the comparison set value may be compared with a value calculated based on the value of the initial threshold current +40@A.

Furthermore, if the code data has content indicating the initial slope efficiency η of the laser, in the first embodiment described above, the comparison can be made by calculating a comparison set value with the differential current.

Furthermore, in the second embodiment as well, the comparison set value can be targeted.

Also, if this code data indicates a threshold current, "OO" → 20+A, "01"
→ 30 shoes A, "10" → 40 shoes A, r
l IJ→50 layers may be a certain amount as shown in the A range.

Next, an example will be specifically explained. In the method of the second embodiment, if the code data has a 2-bit configuration and indicates a threshold current as described above, the code data is read at T811 in FIG. Value current I th = 40 pieces A, so rth + 40 pieces A - 40 pieces A pieces + 40 ■ A - 50 pieces A
◆401A=90mA90mA10. Fv+A/Xt,
It is calculated as Boo 1802tt Boo 84H, rB4++J
As a result, it is determined whether or not to proceed to T812. In other words, in this embodiment, the laser life advance setting value, which differs depending on each laser, is not calculated from the worst value of the laser standard value as in the first and second embodiments, but the data is calculated for each laser. Since the CPU can perform calculations and comparisons based on the data, it is possible to more accurately detect the laser life expectancy.

(3-c) Fourth example Next, a fourth example of laser life prediction will be described.

In this embodiment, the CPU includes, for example, non-volatile RAM.
(hereinafter referred to as NY-RAM) is connected to provide means for storing and holding data regardless of the presence or absence of power supply.

In this example, the La5e
The data obtained when rAPC is executed is stored in the memory storage means, and the data obtained each time La5erAPC is compared with the data stored in the memory storage means to determine the degree of deterioration. The laser lifespan may be predicted based on the judgment.

Next, this will be explained in detail.

First of all, the initial 80% convergence value is stored in NY-RAM, and the subsequent La5erA P
8 by the APC-03 routine of FIG.
Once the 0% convergence value is determined, the process moves from U307 to U314.

At U314, 1/2 the data value of the NV-RAM is put into the A register, and the process goes to U315, where it is added to the NV-RAM data. Then, in U316, the A register data and the 80% convergence value of the D output data are compared. As a result, the process moves to U312, and it is determined whether or not the laser life is predicted. In other words, here, the current 80% convergence value data and the initial 80% convergence value data
The laser life forecast is determined by comparing it with a value 1.5 times the % convergence value data. In general, even if a laser begins to deteriorate, it is said that the usable range is up to a 20% or 50% increase in the initial current amount. Therefore, in this embodiment, the value of 50% increase was set as the laser life prediction setting value.

In the case of this embodiment, since the initial value data changes when the laser is replaced, the storage means is configured on the laser side,
It may be configured such that it can be replaced together with the laser, the storage means may be replaced when the laser is replaced, or the initial value data may be rewritten.

Further, the specific embodiments of the present invention are not limited to the above-described embodiments, and further modifications are possible.

For example, it is possible to apply it to a system using multiple lasers instead of a single laser, and it is also possible to apply it to light ablation control of recording devices, optical communication devices, etc. using other light emitting elements. Also.

- The configurations of the respective embodiments described above may be combined.

[Effect of the Invention 1 According to the present invention, a prediction of the lifespan of a light emitting element is detected by comparing and analyzing a drive current value stored in advance corresponding to a predetermined amount of light emission and a drive current value detected at the present moment. death,
Since this is a warning, it is possible to avoid inconveniences caused by sudden laser lifespan.

[Brief explanation of the drawing]

FIG. 1(a) is a circuit diagram showing a basic circuit of an LBP according to a first embodiment of the present invention. FIG. 1(b) is a circuit diagram showing a modification of the basic circuit. FIG. 2 is a schematic diagram showing an overview of the light amount control operation according to the first embodiment. FIG. 3(a) is a flowchart showing the main routine in the specific operation of the first embodiment. FIG. 3(b) is a flowchart showing the APC-TABLE call routine in the specific operation of the first embodiment. FIG. 3(c) is a flowchart showing an interrupt routine in the specific operation of the first embodiment. FIG. 3(d) is a flowchart showing the APC-RESE routine in the specific operation of the first embodiment. FIG. 3(e) is a flowchart showing APC-5TART/Rechin in the specific operation of the first embodiment. FIG. 3(f) is a flowchart showing the Arc-Nor routine in the specific operation of the first embodiment. FIG. 3(g) is a flowchart showing the APC-01 routine in the specific operation of the first embodiment. FIG. 3(h) is a flowchart showing the APC-02 routine in the specific operation of the first embodiment. FIG. 3(i) is a flowchart showing the APC-03 routine in the specific operation of the first embodiment. FIG. 3(j) is a flowchart showing the APC-04 routine in the specific operation of the first embodiment. FIG. 3(k) is a flowchart showing the Arc-05 routine in the specific operation of the first embodiment. FIG. 4 is a time chart showing the continuous laser-on detection operation in the first embodiment. FIG. 5 is a schematic diagram showing the i-L characteristics of a general laser. FIG. 6 shows that the amount of laser light is 100 in the first embodiment.
A schematic diagram illustrating the state of convergence to the % convergence value is a flow chart showing the APC-03 routine in the second embodiment of the present invention. FIG. 8 is a flowchart showing the APC-03 routine in the fourth embodiment of the present invention. ■... CPU, 2... D/A converter for coarse adjustment, 3... D/A converter for fine adjustment, 4.4'... First constant voltage circuit, 6... Second constant voltage circuit Voltage circuit, 7.7゛...Current switch circuit, 8.8゛...Laser. Figure 1 (O)

Claims (4)

[Claims] (1) Provided in an image forming apparatus that forms a latent image on a photosensitive medium by raster-scanning light emitted from a light emitting element onto a photosensitive medium, the amount of light from the light emitting element is transferred to a light receiving element In a light amount control device that controls the amount of light by adjusting the drive current supplied to the light emitting element based on the detection result, the drive current when the amount of light emission of the light emitting element reaches a first predetermined value. a first storage means for reading and storing values; a second storage means for reading and storing a driving current value when the amount of light emitted from the light emitting element reaches a second predetermined value; a calculation means for calculating the difference between the drive current values; and a detection means for detecting the predicted life of the light emitting element based on the calculation by the calculation means; A light amount control device comprising: warning means for warning; and; (2) Provided in an image forming apparatus that forms a latent image on a photosensitive medium by raster scanning the light emitted from the light emitting element with respect to the photosensitive medium, the amount of light from the light emitting element is measured by the light receiving element In a light amount control device that controls the amount of light by adjusting the drive current supplied to the light emitting element based on the detection result, the drive current value is read when the amount of light emitted by the light emitting element reaches a predetermined value. a storage means for storing; a detection means for detecting a predicted lifespan of the light emitting element based on data in the storage means; a warning means for warning when a predicted lifespan of the light emitting element is detected by the detection means; A light amount control device comprising: (3) A light amount control device according to claim (1), characterized in that the data of any one of the storage means can be set in advance to a data value corresponding to a light emitting element. (4) In claim (1), at least one of the above-mentioned storage means is a storage means that has a backup power source or the like and can store data semi-permanently, and retains initial data of the light emitting element, A light amount control device characterized by calculating a lifespan prediction based on this data.