JPS58189668A - Exposure control system of copying machine - Google Patents

Abstract

PURPOSE:To obtain a copy image of high quality free of density irregularity, by adjusting a phase and an aperture on the basis of the detected value of a detecting means for control over the amount of exposure. CONSTITUTION:A photodetecting element 19 is arranged closely to the slit of a slit plate 16 to photodetect a part of a projected image reflected by mirrors 6 and 7. The photodetecting element 19 detects transmitted light from an original 1 to detect the image density of the original and detects the amount of exposure prior to image exposure to a photosensitive drum 10. With regard to the density detection of the photodetecting element 19, mirrors 6 and 7 are scanned preliminarily prior to a normal exposure process to scan on the original and during this preliminary scanning operation, the brightness of a lamp 2 and the width of the slit are controlled on the basis of the photodetection amount of light of the photodetector 19 to control the amount of exposure to a photosensitive drum adequately, obtaining an excellent copy of the original.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slit-light type copying machine that controls the amount of koji light in accordance with one image of a document.

When making multiple copies of manuscript 1 using the 4-light method on the entire surface at the same time, generally the lightning time is controlled by -j and the Fujimitsu m
f: One type of one-light time control method is used. However, when copying using the slit g source method by moving the IQ411 and the optical system relatively, applying this light time WJ control method requires controlling the speed of the photoreceptor, optical system, slit, etc. Yes, it becomes complicated in terms of 4#llI.

Additionally, the copying speed varies depending on the copy, making it difficult to handle for users who make a large number of copies. Therefore, in a copying machine using the slit exposure method, it is necessary to control the photoreceptor surface illuminance (exposure 1iit) by changing the luminance of the document illumination lamp or the aperture 9, etc. so that the illuminance on the photoreceptor surface (exposure 1iit) becomes appropriate. Conventionally, most of these four control circuits have been constructed using analog devices, and as the circuit itself becomes extremely complex, the number of devices increases, making it extremely uneconomical.

Therefore, in recent years, computers have been developed that are cheaper in terms of processing speed, pressure line, or circuit space.
It has come to be used in I141, and also in the light control method 2, it is possible to control the side by controlling the phase of the alternating current wave supplied to the lamp based on human power data using a microcombiner. Method of controlling the amount of light (% Tosho 56-15
No. 4746 and Japanese Unexamined Patent Publication No. 57-5291) have been proposed.

However, if phase -- is performed, the commercial frequency #IIL number Oi! from the lamp! &i#lI The light containing the non-transferable part of the I wave is output, but the lamp flickers especially when the conduction angle is small, and the image line at* is detected using the p1 light receiving element. In some cases, this may appear as an error.

First, this is a high-speed copying machine, which has a strong tendency to round off, which is a drawback that needs to be solved in copying machines that are currently being used. In addition, when using a halogen lamp as a document illumination lamp, if it is used with a small conduction angle, halogen lamps will not be present, and the lamp's surface will become a medium, shortening the life of hemorrhoids. There were 0II411 questions.

Alternatively, when changing the copying magnification from small to large, it is necessary to change the amount of light over a large range, and therefore the phase of the alternating current wave supplied to the lamp must be greatly controlled. When the conduction angle is made small in order to increase the amount of light, the above-mentioned problem occurs in ttas.

The present invention has been made in view of the above circumstances and has been devised to eliminate the above drawbacks.In a slit exposure type copying machine,
- By controlling the phase and aperture of the alternating current wave based on m11 degrees, the phase is always controlled within the appropriate range.
It is an object of the present invention to provide a storm light control method for obtaining a high-quality copy image without unevenness of stinging without impairing the quality of lamp lighting.

The present invention &j1 will be explained below with reference to the drawings.

FIG. 1 shows an electrophotographic copying machine, in which a microfilm storage bucket 1 is illuminated by an illumination device consisting of an illumination rung 2, a spherical reflector 3, and a condensing lens 4, and the image light from the tray 1 passes through a projection lens 5. The light is then reflected by the flat mirror 6.7 and projected onto the photosensitive drum 10 through the slit 9 of the sleeve 4118. The mirror 6.7 is attached to the support 1 in a perpendicular intersecting relationship.
1, and support 11#i<ra 6, 7
move in the direction indicated by the arrow. mirror 6,7
Normally, when the light ends at the home position, it moves back and returns to the home position. The photosensitive drum 10a rotates once at a constant speed in the direction indicated by the arrow 9B, and the mirror 6.7 moves at a speed of i, which is the circumferential speed of the photosensitive drum 1, in cycles of one rotation of the photosensitive drum IOC). A slit plate l@ having slits 15 is arranged immediately in front of the photosensitive drum 1G.
With the above configuration, the JIT side 1 is divided into slits and placed on 11m of the photosensitive drum 10 through the slit 15. The image on the entire surface is exposed to light on the photosensitive drum 19.

A light-receiving element 19 is placed near 150 of a 1m plate (strip), and the projected image reflected by the mirrors 6 and 7 -
The light receiving element 19, which is adapted to receive sr light, detects the transmitted light of the original 1 and detects 11i11 & 1111m of the original, and detects the amount of exposure before exposing the photosensitive drum 50 to the light.

This detection of 1lliIt by the light-receiving element 19 is carried out by pre-scanning the mirror 6.7 on the regular dust 4!4 surface and scanning the document, and adding 1
The brightness of rung 2 and the width of slit 15 are 11141.
i1, thereby appropriately controlling the amount of side light to the photosensitive drum, resulting in a good copy of the original.

Regarding FIG. 2, the slit plate 16 is held freely by the 0 slit width changing plate 201 in order to change the - of the slit 15. The variable plate 2o is biased in the direction of the arrow by the tension spring 21. While working, solenoid 22 moves arrow D'
configured to move in the direction. Slit plate 16
The pin 23 fixed to the long hole 24 formed in the variable plate 20
The variable plate 2o can be moved by the length of the elongated hole 240 in the force direction D and D'. The solenoid 22 is driven by a signal from a microcomputer, which will be described later, to move the variable plate 20t in the direction of the arrow D', thereby causing the variable plate 2o to cover a part of the slit 16C) and close the slit 1
50 width becomes narrower, and the amount of light passing through the slit 15 decreases.

FIG. 3 shows a circuit for controlling the exposure amount based on the digital value processing of the microcombiner 21. The image chain intensity signal obtained by the light receiving element 19 is amplified by the output amplification circuit 34, and then The photometric value detection signal is input to the multiplexer 34 via the 1gl path 35.The voltage of the unidirectional AC power source (AClooV) 37 is converted to a peak voltage by the transformer 38, and its step-down output (if kept
15V) is double-wave rectified by the rectifier a circuit 39, the peak value of the power supply voltage (15V) is detected and held by the peak value detection circuit 40, and this peak value is inputted to the multiplier 36. Multi-Glexer A6U manual power 1 (photometric value of detection circuit 3s) or input 2 (detection - M4 (1t2) power supply voltage P1 value)'
is selected and sent as analog data to the iA/'D<'I analog data conversion circuit 41.The A/I) conversion circuit 41 converts this 1 analog data into digital data and sends it to the CPU central processing through the I10 port 42. device) 45. The CPLJ 45 internally processes the data of the photometric value and the power supply voltage peak value, and sends a signal to the phase control circuit 46 and the lunoid drive control circuit 47 in order to turn off the photosensitive drum lO and turn the lamp on. The phase angle of the alternating current wave and the slit are smooth. The supply power of the illumination lamp 2 is controlled in phase by a bidirectional thyristor (hereinafter referred to as a trybook). In order to perform the phase tb+I Ht on the microcomputer, the CPU
45 needs to determine the zero-crossing point of the AC applied to the lamp 2, and for this purpose the AC voltage generator 37 is connected to the transformer 50.
The step-down output (ACIOV for f/lI) is waveform-shaped by the zero-crossing circuit 51, and the CPLJ45 is used to convert the zero-crossing point array into a separate port No. 16 and convert it into an I10 boat 4.
2 is passed through and input to the CPU 45.

The basic concept of phase control using a microcomputer used in the present invention will be explained using FIG.
The zero-crossing point (X
I, xt,
At this point, a timer is set in the CPU 4S, a time-up signal of the timer is output from the I10 port 42, and this signal is used to conduct the triac in the phase control circuit 4@, so that the timer is set in the CPU 4S. It performs phase control. The set time T of the timer that determines the conduction angle of the triac is controlled by the #1 light value of the field value detection circuit 35 and the peak value of the peak value detection circuit 40, etc., and thereby the effective power applied to the lamp 2 is adjusted. .

Next, details of the exposure amount control method O will be explained with reference to flowcharts shown in FIGS. 5 and 6. In order to control the phase so that Lanf-2 lights up at the photometric standard of 14 degrees (the brightness at 9 o'clock is 100X and the brightness at 9 o'clock is set to 70 @ OXK), the side light is used. A timer is set, and the lamp 2 is lit at the standard 'S degrees in the rung lighting routine of step (2). At this time, Sri y ) Is
The width of is set in advance to a predetermined state at the time of sidelighting.

The lamp lighting routine lights the lamp 2 at a phase determined by the set time of the lighting timer while compensating for power fluctuations as will be described later.

In this rung lighting routine, mirror 6 is turned on while lamp 2 is lit.
．． 7 to scan the original t11, the light receiving element 19 receives light from the document t11, and when photometry is completed in step 2, a photometry end signal is sent from the 1-sequence control microcombination controller (not shown). Turn off lamp 2. Next, in step (4), the multi-bleph sensor 36 selects manual power 1 based on the signal from the CPU 45, and the single light value from the light receiving element 19 is sent to the M/D converter 41. CP converts photometric values into digital data via
Incorporate it into U45. Next, in Steno No. 8, the digitally converted 9#j light value and the reference value are compared, and m feet 1llO
If the measured value is smaller, proceed to step ■, [YES] to calculate the 10th phase angle corresponding to the photometric value, and if the measured value is smaller, proceed to step (2) and calculate the 20th phase M corresponding to the photometric value.
Step 1 is to set the appropriate lamp # degree based on the photometric value ↓ Control only the phase angle, and when the triac is round, the triac quadrature angle is small, and the lamp is in the middle or , Compare the photometric value with the reference value to determine whether the copied image is bulging, and if the 4-tongue angle needs to be made smaller, step ①.

■ Perform O treatment m, connect the phase and slit to conduction angle t, and reduce the exposure amount at all without reducing J\[IIL, otherwise perform step Only use moxibustion to properly control the exposure amount (see table).
Store the relational expression between the appropriate lamp brightness and the phase-control tie-rg) time in the internal memory, and then repeat this relational expression based on the original information. A time-up for phase control is performed at the 9th set time corresponding to the cD value, and at the time of time-up, a phase control bat & 11 fil f is performed. Step (
In α, (2), the phase angle at each photometric value is calculated, and a time-up for phase control is performed in order to obtain an appropriate lamp degree.

If the value of -j5 is larger than the reference value, step
(In &, the CPU 45 sends the lunoid drive l#J signal to narrow the slit width, and in the lamp lighting routine of step -〇, the CPU 45.i>a
Lung 2 is lit by the phase control pulse outputted from the phase control circuit 46, and rung 1 is turned on via the phase control circuit 46.
The solenoid 22 is turned on via the slit 150 to close the slit 150-. As a result of the above, the photosensitive drum 10 has the document II [
By using the lamp 2 at an appropriate brightness level, flicker in the rung and uneven density in the copied image will not occur. On the other hand, if #j original value is smaller than the reference value, in step ■, the timer is set to the time corresponding to the photometric value, the slit 15 is left open, and step i, CPtJ4
The light is turned on at the phase angle determined by the phase control pulse from No. 5 and the set time of the 2t timer. In step (2), when the exposure end signal is manually input from the microcomputer for controlling the Geetance 11 at the end of the dust exposure, the main routine ends.

Next, the lamp lighting routine shown in FIG. 6 will be explained. First, in step (2), wait for a zero-cross signal, and when the zero-cross signal is input from the zero-cross detection circuit 51,
In step 0, a timer is started. In step (S, 1), a phase control pulse is output to the phase control circuit w1146 at the same time as time up, and the lamp is lit at the phase angle set by K.Next, in step
In the case of Hz, it is determined whether 5 maac has elapsed since the zero-cross signal input, and in the case of 60 Hz, it is determined whether 4.2 maac has elapsed since the zero-cross signal input. Is this maintained at 1/4 of the power supply voltage level since the peak? The rounding is done manually inside the cycle. STELAPRI Co., Ltd. sends a signal to the multiplexer 36 9, selects input 2 (power supply voltage peak b>), and inputs the power supply voltage peak value to the CPO 45 as digital data via the M/D conversion circuit 41. Step [phase].

(With the gentle setting, the conduction angle depth t is corrected based on the Mee voltage peak value so that the brightness of the lamp does not change even if the power supply changes. A new timer is set, and steps @ ~ O [will be repeated until -1 light or the end of exposure.In addition, when calculating the correction amount at step (season), the relationship between power supply voltage peak value - correction amount This is done by storing the formula t in the memory in the CPU 45 and ν.In the case of Eki Sousei, the slit width was changed by only one step, but this slit width can be changed to multiple steps. Control the exposure amount by combining the phase and conduction angle, or continuously open the slit.
By changing the slit width, phase angle, and controlling the exposure amount in relation to t, it is possible to use the lamp with a large conduction angle without greatly changing the brightness of the lamp. It is possible to obtain stable brightness under optimal conditions, and the life of the lamp can be extended. Furthermore, in response to a large change in the copying magnification of the original document, the exposure amount can be greatly changed to a state of II/2.

In the above experiments, the phase is controlled digitally by a microcomputer, but the phase may also be controlled analogously.

Alternatively, as a method for controlling the diaphragm, instead of changing the slit width, a diaphragm may be provided between the lamp and the document, and the amount of light transmitted through this diaphragm may be varied.

As described above, according to the present invention, it is possible to prevent flickering of the lamp, unevenness of the copied image, etc., to always obtain a copied image of good quality, extend the life of the lamp, and further improve the quality of the S manuscript. At, it is possible to appropriately control the amount of side illumination even when the copying magnification is large.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a multi-four machine, showing one feature of the present invention;
The figure is a schematic diagram of one implementation in which the slit width is varied according to the present invention.
FIG. 3 is a block diagram of the exposure control path of the present invention, FIG. 4 is a diagram for explaining the phase control method of the present invention, and FIGS. 5 and 6 are 70% of the program for implementing the present invention. -It is a chart. 2...Lamp, 16...Slit plate, 19...Light receiving water child. Applicant: Canon Co., Ltd. Representative: Gi Marushima -ゝ゛I Vehicle I-1

Claims (2)

[Claims] (1) In a copying machine that illuminates the original with light from a lamp and makes copies using the original O image T slit iris tip, there is a means for detecting m degrees of the original, and an AC RRID phase that is supplied to a lamp lit by an AC f& source. and a means for controlling the aperture, and the amount of light is adjusted by adjusting the phase, the aperture, and the f:l114 based on the detected value of the detection means. Exposure control method for copying machines. (2) The exposure control system for a copying machine according to claim 1, wherein the diaphragm p consists of a slit with a variable slit width.