JPS6054561A - Optical output stabilizing device - Google Patents

Abstract

PURPOSE:To easily and surely perform the adjusting work of an optical output stabilizing device with no special measuring instrument, such as a lux meter, etc. by measuring the output level of a photodetector when a light source is driven and changing a reference value based on the measured value. CONSTITUTION:The output signal Vd of an amplifier 7 is supplied to a controller 12 after it is converted into a digital signal Dd by an A/D converter 11. The controller 12 calculates a deviation for feedback control based on the signal Dd and outputs the lighting control pulse P of a duty corresponding to the deviation. The lighting control pulse P is supplied to a manual switch 33 and, at the manual switch 33, the pulse P is switched to the reference pulse Ps with a prescribed duty ratio generated from a reference pulse generator 32 and the reference pulse Ps is supplied to a dim stabilizer 2. At the stabilizer 2 the output level of a photodetector 6 is measured by means of a voltmeter which is not shown on the figure from a photodetecting level measuring terminal 30 and the updated value Ds of the reference value updated based on the measured value is inputted into the controller 12 from an operation input section 34, and thus, the reference value is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a device for stabilizing the output light of a light source used in a scanner such as a copying machine or a facsimile machine.

[Prior art]

Generally, in a scanner of a copying machine or a facsimile machine, it is necessary to stabilize the output light intensity of a light source in order to maintain constant document reading conditions, and a light output stabilizing device is provided for this purpose.

FIG. 1 shows an example of such a light output stabilizing device. In the figure, 1 is a fluorescent lamp serving as a light source, 2 is a dimming stabilizer that drives this fluorescent lamp 1, This dimming ballast 2
Its operation is controlled by a lighting control pulse P applied by an i4 pulse width modulator 3, which will be described later. Further, 4 is an AC power source.

5 is an optical fiber that guides a part of the output light of the fluorescent lamp 1 to a photodiode 6. The output signal of the photodiode 6 is amplified by an amplifier 7, and the output signal Vd of this amplifier 7 is input to the Applied to the comparison input terminal.

Reference numeral 9 denotes a setting device for setting a level signal corresponding to the output signal Vd of the amplifier 7 when the fluorescent lamp l outputs light of a predetermined intensity as the reference value signal Vr. is applied to the reference value input of comparator 8.

Therefore, the comparator 8 compares the reference value signal Vr and the signal Vd, calculates the deviation, and calculates the deviation by a deviation signal V.
e is applied to the pulse width modulator 3.

10 is a main pulse generator that generates a reference pulse PO to be given to the main pulse width modulator 3. The pulse width modulator 3 forms lighting control/J pulse P in which the duty of the reference pulse PO is changed in accordance with the applied deviation signal Ve.

For example, if the reference signal PO is a signal with a period T and a pulse width Td as shown in part PI of FIG. 2(a),
When the deviation signal Ve changes as shown in FIG. Pulse P as shown in P3
change the pulse width. In this manner, feedback control is performed so that the output light of the fluorescent lamp 1 has a predetermined intensity.

Incidentally, in such a light output stabilizing device, errors in the mounting position of the end face of the optical fiber 5, errors in the mounting position of the light receiving surface of the photodiode 6, and
Due to variations in characteristics (sensitivity), etc., the level of the output signal Vd of the amplifier 7 relative to the output light level of the light source (fluorescent lamp 1) may deviate from the expected relationship and vary greatly.

Therefore, it is necessary to eliminate such variations and adjust the light intensity of the light source to a predetermined value, but this adjustment work involves inserting an illumination meter etc. into the housing of the copying machine, etc., and checking that the illuminance meter measures the prescribed luminance. This is a complicated task, such as operating a variable resistor to change the gain of the amplifier 7 or operating the setting device 9 as instructed.

In this way, the conventional light intensity adjustment work for light output stabilization devices requires special measuring instruments such as illuminometers, and it is necessary to precisely mount the light detection part of this illuminometer at a predetermined position relative to the light source. Since a dedicated jig is required, there is a problem in that it requires a great deal of cost and effort. For this reason,
It is not easy for service personnel to carry the above-mentioned special measuring instruments and jigs during maintenance inspections, making adjustment work extremely difficult.

〔the purpose〕

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a light output stabilizing device that allows adjustment work to be performed easily and with high precision.

〔composition〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 3 shows an embodiment of the optical output stabilizing device according to the present invention.

In the figure, 11 is an analog/digital converter that converts the output signal Vd of the amplifier 7 into a corresponding digital signal Dd, and the digital signal Dd is applied to the controller 12. The analog/digital converter 11 receives a conversion start signal SC (Stant C) from the controller 12.
When the signal RY (Read
Y) is returned to the controller 12 to notify that the conversion has been completed.

The controller 12 calculates the deviation of feedback control based on the input signal Dd, and outputs the duty lighting control pulse P corresponding to this deviation.

Reference numeral 30 represents a received light level measuring terminal for extracting the output signal Vd of the amplifier 7 to the outside, and 31 represents a switch for instructing the controller 12 to set an adjustment mode.

32 is a reference pulse generator that generates a reference pulse P8 having a duty to light the fluorescent lamp 1 at a predetermined luminous intensity; 33 is a lighting control pulse P output from the controller 12;
A manual switch 34 switches between the reference pulse Ps and the reference pulse Ps and applies it to the dimming stabilizer 2, and 34 is an operation input unit that serves as a means for changing the reference value Rd, which will be described later.

FIG. 4 shows a specific example of the cositroller 12. In the same figure, 12a is a microcomputer (hereinafter referred to as MPU) equipped with multiple input/output units.
, 12b is a timer register for setting the pulse width Td of the lighting control pulse P, 12c is a timer register for setting the period T of the lighting control pulse P, 12d and 12
e is a digital comparator, 12f and 12g are clock pulses C when a start pulse is applied to the start input terminal ST.
Enables the input of P and clears the input terminal CL.
A timer that clears the contents when a clear pulse is applied to it, and 12h is a flip-flop that outputs a lighting control signal P.

Further, the digital comparator 12d compares the set value of the timer register 12b and the counted value of the counter 12f, and if they match, outputs a match pulse EPI, and the digital comparator 12e compares the set value of the timer register 12c and the counted value of the counter 12g. If they match, a matching i4 pulse EP2 is output. These coincidence pulses EPI and EP2 are both applied to the trigger input terminal T of the flip-flop 12h via the OR circuit 12i to invert the state of the flip-flop 12h, and the coincidence pulse EP2 is applied to the trigger input terminal T of the flip-flop 12h.
, 12g to clear the counters 12f and 12g, and the MPU 12
The lighting control signal P is applied to the interrupt input terminal INT of a.
The MPU l 2 a is notified that one cycle of has ended.

Note that the counters 12f and 12g are clock pulses CP
The counting operation continues while the input is enabled.

With the above configuration, the operation when the switch 31 is not turned on and the controller 12 stabilizes the light amount of the light emitting lamp 1 at the set value in the normal mode will be explained. In this case, the Fi'tPU 12a of the controller 12 executes the grodarum shown in FIG.

That is, first of all, the initial setting value Cdo of the nof pulse width is set in the timer register 12b to set the duty of the lighting control pulse P to the reference state (for example, the duty is 0.6). A cycle setting value Ct for setting the cycle T is set in the timer register 12c (process 21). After this, for example, as shown in FIG. 7(b), a start pulse ST is output at time to to start the counters 12f and 12g and set the flip-flop 12h (22), and a pulse is input to the input terminal INT. (4-1J times 23)
The result is N.

loop).

Now, as described above, when the start pulse ST is output at time to, the flip-flop 12h is set and the lighting control pulse P rises to the logic level H. Further, since the counting operation of the counters 12b and 12c is started at time to, at time t1, when a time corresponding to the pulse width of the lighting control pulse P has elapsed from this time to, the counter 12.
When the count value of f matches the pulse width initial setting value Cdo,
The digital comparator 12d outputs a coincidence pulse EPI, which triggers the flip-flop 12h and inverts its state. As a result, the lighting control pulse P becomes logic W.
vpehLVC falling F) This i4 pulse width of the i4 pulse P is controlled to the value determined by the set value Cdo.

Thereafter, at time t2, that is, when the period T of the lighting control noculus P has elapsed from time to, the count value of the counter 12g matches the period setting value Ct, so the digital comparator 12
A coincidence pulse EP2 is outputted as shown in FIG. 7(C), which triggers the 7-lip flop 12h and reverses its state, so that the period of the lighting pulse P becomes T.

Also, when the coincidence nogle EP2 is output, the counter 1
, 2f, and 12g are cleared and their count values are set to '0', and at the same time, the logic level of the input terminal INT of the MPU 12a becomes H, so the result of judgment 23 is YES, and as a result, the MPU 12 .a executes the next process 24, that is, duty control process.

As shown in FIG. 6, in this data control process, first, the signal SC is output to the analog/digital converter 11.
Start. Then, when the conversion is completed and the ready signal RY becomes a logic level H, the output data Dd of the analog/digital converter 11 is input.

Then, the setting value Rd corresponding to the light reception level setting value is read out, the deviation from the input data Dd is calculated, and the data deviation (Id) is calculated by further multiplying by a constant K.

Next, set value Cd (in this case, Cdo
) is updated and the updated setting value cd is stored in the timer register 12b.

Therefore, the next lighting control 1? The pulse width of the pulse P is changed to a time corresponding to this updated setting value Cd.

The above judgment 23 and processing 24 are repeatedly executed while the light emitting lamp 1 is lit, that is, while the result of judgment 25 is NO, and the pulse width of the lighting control pulse P is updated each time. In this way, feedback control is performed so that the output light of the light emitting lamp 1 is maintained at a constant intensity.

Note that the determination 25 becomes YES when the light source is not used, for example, when copying is completed in a copying machine, and the program ends. 'j 7C, Match Noculus E
When P2 falls, counter 12f.

12g restarts the counting operation of clock pulses cp.

Next, the adjustment work in this embodiment will be explained.

When performing adjustment work, first turn on the switch 31 to select the adjustment mode, switch the manual switch 33 to the reference pulse generator 32 side, and then connect the measuring point of a voltmeter (not shown) to the received light level measurement terminal 30. Connect.

Accordingly, since the reference noyals ps is applied to the dimming ballast 2, the output signal Vd of the amplifier 7 when the light emitting lamp 1 is lit with a predetermined amount of light is measured with a voltmeter. Then, the gain of the amplifier 7 is adjusted with a variable resistor so that this voltmeter indicates the reference value of the output signal Vd.

As a result, the manual switch 33 is switched to the controller 12 side, the switch 31 is turned on again, and the controller 1
When the light emitting lamp 2 returns to the normal control mode, the amount of light from the light emitting lamp 1 is stabilized to a predetermined value by the action of the MPo 12 a as described above.

Note that when the adjustment mode is selected as described above, the controller 12 is in a standby state and does not perform the optical output stabilization control as shown in FIG. 5.

Further, the update value Ds of the reference value corresponding to the measured value of the voltmeter in the adjustment mode is transmitted from the operation input unit 34 to the controller 12.
may be input to change the reference value Rd to Ds.

FIG. 8 shows another embodiment of the optical output stabilizing device according to the present invention. In this embodiment, in the adjustment mode, the output data of the analog/digital converter 11 is displayed on the display section, making a voltmeter unnecessary.

In the figure, a display section 35 is used to display the number of copies, etc. in a normal copying machine, and displays display data output from a display control section of the copying machine and output data from an analog/digital converter 11, which are not shown in the figure. Dd is selected by the data selector 36 and added.

Further, the data selector 36 is controlled by a switching control signal output from a main body control section (not shown). Similarly, the lighting control output from the controller 12, -e Lus P and reference A? A switch (automatic switch 933a) for switching the reference pulse Ps generated by the pulse generator 32 is also controlled by the switching control signal, and thereby the data selector 36 and the switch 33a are interlocked.

Note that the other parts are the same as the apparatus shown in FIG. 3 and will therefore be omitted.

Therefore, when the switch 31 is turned on and the adjustment mode is selected, the data selector 36 and the switch 33a are switched, whereby the reference pulse P is applied to the dimming ballast 2 and the data DdO value at this time is displayed on the display. 35
is displayed.

Then, by adjusting the gain of the amplifier 7 so that the display on the display section 35 at this time reaches a predetermined value, the light amount of the light emitting lamp 1 can be stabilized at a predetermined value as in the above embodiment.

FIG. 9 shows still another embodiment of the optical output stabilizing device according to the present invention. In this embodiment, the functions of the reference pulse generator 32 and the switch 33a are also performed by the controller 12, and the switching control of the data selector 36 is also performed by the controller 12. Note that the other parts are the same as the apparatus shown in FIG. 3, and will therefore be omitted.

In this embodiment, since the reference pulse P8 is also formed and outputted by the controller 12, the program shown in FIG. 10 is executed.

That is, when the switch 31 is turned on and the adjustment mode is selected, the result of the judgment 26 is YES, and the Noyals width Tis corresponding to the pulse width of the reference pulse Pg is prepared.
Set ds in the timer register 12b (process 27)
.

In this manner, in the adjustment mode, the controller 12 does not execute the duty control process 24 described above, but executes control to output the reference pulse ps, and outputs the reference pulse Pa to the dimming ballast 2.

In addition, when the adjustment mode is selected, the controller 12
applies the switching signal SS to the data selector 36 to select the output data Dd of the analog/digital converter 11. As a result, the output data Dd of the analog/digital converter 11 is added to the display section 35 and displayed.

Note that the operation in the normal control mode is the same as in the embodiment described above, so a description thereof will be omitted.

Therefore, in the adjustment mode, the gain of the amplifier 7 is adjusted so that the display on the optical indicator 35 becomes a predetermined value, or the updated value D8 of the reference value Rd corresponding to this display value is input from the operation input section 34. By inputting multiple inputs, the light amount of the fluorescent lamp 1 can be stabilized at a predetermined value when returning from this adjustment mode to the normal control mode.

Although each of the embodiments described above uses a fluorescent lamp as a light source, the present invention is not limited to this, and the present invention can also be carried out when an incandescent lamp or the like is used as a light source. According to the present invention, the output level of the light receiving element is measured when the light source is driven to obtain a predetermined amount of light, and the reference value of the measured value is changed based on this measured value. An advantage is obtained that adjustment can be easily and reliably performed without requiring a measuring device to measure the luminous intensity of the light source.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating an optical output stabilizing device, FIGS. 2(a) and (b) are operational waveform diagrams of the device shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing an embodiment of the invention. FIG. 4 is a block diagram specifically showing the controller. FIG. 5 is a flowchart showing an example of a noogram executed by the MPU. FIG. Flowchart, Figure 7 '(a)-(d) C:'
7) A waveform diagram showing the operation of the roller; FIG. 8 is a block diagram showing another embodiment 91I of the present invention; FIG. 9 is a block diagram showing still another embodiment flJ of the present invention; The figure is a flowchart showing a program executed by the apparatus shown in FIG. DESCRIPTION OF SYMBOLS 1... Fluorescent lamp, 2... Dimming ballast, 5... Optical fiber MA, 6... Photodiode, 7... Amplifier,
11...Analog/digital converter, 12...Controller, 3Q...Light receiving level measurement terminal, 31...
Switch, 32... Reference pulse generator, 33... Manual switch, 33a... Switch, 34... Operation input section, 35... Display section, 36... Data selector. Figure 2 Figure 3 Figure 4 Figure 7 (d) EP2~ Figure 5 Figure 6 Figure 8 To Figure 2 Figure 9

Claims (1)

[Claims] Guides the output light of the light source to a light receiving element, compares the output signal of this light receiving element with a reference value to determine the deviation, and controls the driving means of the light source in response to this deviation. - Changes the duty of the base pulse signal. In the light output stabilizing device, the light receiving level detecting means detects the output signal of the light receiving element, and the standard difference/4' pulse generating means generates a reference pulse signal of a predetermined duty to make the output light of the light source a predetermined intensity. characterized in that the reference value or the output signal level of the light receiving element is changed in response to the detection value of the light reception level detection means when the reference pulse signal is applied to the drive means as a control signal. Light output stabilization device.