JPS5955424A - Dimmer for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To detect accurately the quantity of irradiation light in copying operation and to perform proper exposure, by arranging a photodetecting element to the position where the light irradiating an original from a light source is not prevented. CONSTITUTION:A reflecting mirror 10 arranged in parallel to a long and thin fluorescent lamp 1 has a lighting window 11 cut long and thin in the lengthwise direction of the fluorescent lamp 1 where the light from the fluorescent lamp 1 to the original 8 is not prevented and large influence upon the quantity of light to the original is not exerted. A photosensor 3 goes and returns to the overall length of the fluorescent lamp 1 throughout when the fluorescent lamp 1 turns on for copying and the total detection amount of light in a single going and returning period of the photosensor is detected; when the quantity of light of the fluorescent lamp 1 deviates from a set value, the electric power supply amount to the fluorescent lamp 1 is adjusted stepwise every time the photosensor 3 goes and returns once. Therefore, the quantity of light of the fluorescent lamp 1 is controlled to a specific value throughout the copying period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light control device with high light control performance in an electrophotographic copying machine using an elongated light source such as a fluorescent lamp as an exposure light source.

In electrophotography, which uses a long and narrow light source, the light source is long, so the intensity of / is not uniform due to the influence of temperature, etc.
As a result, when only the intensity of γ near a specific part of the light source was detected, the detected light amount was deviated from the average nine over the entire length of the light source.

In order to eliminate such inconveniences, conventionally, as shown in FIG.
Slideably attach the pulley 4 along the same shaft 2.
5, an endless wire 6 is connected to the wire 6, and the optical sensor 3 is connected directly to the pulley 4 by utilizing the time from when a copying signal is input to when copying is started. The motor 7 is rotated at a constant speed in forward and reverse directions, and the sensor 3 is moved over the entire length of the fluorescent lamp 1 to move it back and forth.
The illuminance of the fluorescent lamp 1 was appropriately adjusted by the control device 9 based on the total amount of light detected during the round trip.

In such a light control device. Although it is possible to accurately detect the amount of light immediately before copying because it detects the light that is being irradiated from the fluorescent lamp 1 to the document 8, it is not possible to detect the amount of light during copying, so the copying time is The Tawara printer was not suitable for long manuscripts.

In addition, with the light control device, the source/server 3 is moved back and forth before copying starts, so it is difficult to shorten the time it takes for copying to start when the copying signal is input manually. It was me.

Has the present invention overcome these points? The purpose of improving the adjustment device of the Ryoda Teisho copying machine is from the light source to the manuscript! By placing the light-receiving element in a position that does not interfere with the emitted light, the light receiving element can be placed in a position that does not interfere with the emitted light. ! The object of the present invention is to provide a light control device that can accurately detect the light source and perform dropwise exposure.

The present invention will be explained below based on the example illustrated in FIGS. 2 to 3.

A part of the reflecting mirror 10 arranged parallel to the elongated fluorescent lamp 1 that does not impede the light emitted from the fluorescent lamp 1 onto the original 8 and does not have a significant effect on the amount of light on the original 8. A light window is formed by cutting out the fluorescent lamp 1 narrowly along its width in the longitudinal direction.

Still the above-mentioned opening window! A shaft 2 is installed parallel to the shaft 2, and the sensor 3 is slidably attached to the shaft 2 opposite to the lighting window, and the shaft 2 is driven by the shaft 7. en-less wire 6
Then, the optical sensor →-3 is connected.

Furthermore, the control device 12 is constructed as shown in FIG.

Photodio! More optical sensor 3 is operational amplifier 1
30 is connected to the input terminal, and the output of the same operational amplifier 13! The terminal is connected to transistor 150 through resistor 14.

The negative terminal of the capacitor 16 is connected to a constant voltage power supply 18 via a field effect transistor 17, and the other terminal of the capacitor 16 is grounded via the collector-emitter of the transistor 15.

Furthermore, the gate of the field effect transistor 17 is the switch 1.
The gate of the field effect transistor 17 is connected to the constant voltage power supply 18 through the a contact of the switch 19 and the base of the transistor 20 through the b contact of the switch 19. The base of is followed by Δ.

Furthermore, the collector of the transistor 20 is
The emitter of the transistor 20 is connected to one terminal of the transistor 20 through a resistor 23.

One terminal of the power source 16 is connected to a voltage level conversion circuit 25 via a switch 20 and a resistor 25, and is also connected to a Nintendo 28 via a switch 21 and a resistor 27.

But +-! The phase conversion circuit 26 converts a Hals signal with a required phase lag to the main power source of the AC source 20 to the dimming circuit 30, depending on the magnitude of the human power source.
It is supposed to be sent to.

The horizontal dimmer circuit 30 is equipped with a constant voltage for adjusting the relay switch and a constant voltage, and the alternating current power supply voltage must become zero after the moment when it receives the gate pulse signal from the above-mentioned phase change % circuit 26. During this time, the thyristor is in a conductive state to control the output to the fluorescent lamp 1.

Further, the a contact point of the switch 19 is controlled to be on/off so that it is turned on when the optical sensor 3 starts forward movement and turned off before the end of the backward movement, and the switch 24 is
Main-off control is performed so that the contact turns on after the contact turns on, and turns off before the a contact turns off.

The embodiment shown in FIGS. 2 and 3 is constructed as described above, so that when the fluorescent lamp 1 is turned on, the light sensor 3 is activated by the positive light of the morph 7 during the copying operation. By reciprocating, the light beam 13 is received over the entire length of the fluorescent lamp 1. When the light sensor 3 receives light, a current flows through the sensor 3 in proportion to the amount of light received, and a voltage is applied from the operational amplifier 13 to the base of the transistor 15 through the resistor 14 in proportion to this current value. Ru.

During the reciprocation of the tail sensor 3, the a contact of the switch 19 is turned on and a constant voltage is applied to the gate of the field effect transistor 17, which becomes conductive and the capacitors 16 and 28 are turned on. The voltage is applied to the jealous child. At this time, since the transistor 15 is in a conductive state, the hydrants 16 and 28 are filled as not shown in FIG. 4, and their voltage increases.

Next, when optical sensor 3 reaches the front of the return surface, switch 2
7 becomes a contact, and then the a contact of the switch 19 turns off and the b contact of the switch 19 becomes a main, so the world effect transistor 17 becomes non-conductive, and the transistor 2o becomes conductive, causing the capacitor 1G to Full? The generated charge is discharged, and the voltage of the capacitor 16 becomes zero. On the other hand, the voltage of the capacitor 28 is held constant as shown by the dotted line in the fourth line.

Roughly, the voltage of the capacitor 16 increases as the optical sensor 3 moves back and forth, and if its extreme value differs, the voltage of the capacitor 28 also changes step by step, and this voltage is directly applied to the one-voltage phase conversion circuit 26. Ru.

In addition, the voltage phase conversion circuit 26 delays or advances the phase of the gate pulse signal sent to the dimmer circuit 30 depending on the magnitude of the input voltage, and the dimmer circuit 30 supplies the gate pulse signal to the fluorescent moon 1. The electric power is out of adjustment, and the amount of light emitted from the backlight 1 is controlled to be constant.

In this way, in the above embodiment, the optical sensor 3 reciprocates over the entire length of the fluorescent lamp 1 during the entire period when the fluorescent lamp 1 is lit and copying is performed, and the optical sensor 3 reciprocates during one reciprocation period T0. If the total amount of light detected in the light sensor 3 fails to detect each time the light sensor 3 returns and the light amount of the bellows lamp 1 deviates from the set value, the light sensor
The number of power supplies to the fluorescent lamp 1 is adjusted stepwise every time the fluorescent lamp 1 goes back and forth.

Therefore, the light intensity of the fluorescent lamp 1 can be controlled to match a predetermined setting value throughout the entire copying process, so that proper exposure can be achieved when copying a long original.
In addition, the copy start time can be shortened.

In the present invention, the light-receiving element is arranged so as to be movable along the light source at a position that does not obstruct the light irradiated onto the document from the elongated light source for exposure, and the light-receiving element is moved during multi-γ while the light is emitted. Since a means for detecting the intensity of the light source is provided, the light receiving element is moved along the light source during the entire period when the light source is on and copying is being performed, and the light receiving element is moved along the light source to detect the light that the light source is actually exposed to. The light source can be controlled to obtain the optimum amount of light by sensing the light intensity.

Furthermore, in the present invention, it is not necessary to turn on the light source for exposure two hours in advance and then detect the light intensity of the light source and control the light source before copying starts, so the period until copying starts can be shortened. In addition, a long original can be copied with an appropriate exposure amount.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a conventional control device for an electrophotographic copying machine, FIG. 2 is a schematic perspective view showing an embodiment of a light control device for an electrophotographic copying machine according to the present invention, and FIG. 4 is a circuit diagram of the control device of the same embodiment, and FIG. 4 is a characteristic diagram showing the state of change in the voltage converted from the amount of light detected by the optical sensor in the same embodiment as a function of time. . DESCRIPTION OF SYMBOLS 1...Fluorescent lamp, 2...Nyaft, 3...Sensor, 4, 5...Pulley, 6...Endless wire,
7...Motor, 8...Document, 10...Reflector, 1
DESCRIPTION OF SYMBOLS 1... Window, 12... Control equipment, 13... Operational amplifier, 14... Resistor, 15... Transistor, 1
6... Kogodesoza, 17... Field effect transistor, 18... Constant voltage power supply, 19... Switch, 20...
...Transistor, 21...Resistor, 22...Capacitor, 23...Resistor, 24...Switch, 25...
・Resistor, 26... Voltage phase conversion circuit, 27... Resistor, 28... Capacitor, 29... AC power supply, 30...
...Dimmer circuit. Agent: Patent attorney Nozomi Ebara and 1 other person

Claims (1)

[Claims] An adjustment/device for an electronic photocopier that detects the intensity of light from a long and slender exposure whale using a receiver and controls the exposure light source to obtain an optimum light amount based on the detected light amount, ! + in a position that does not block the light irradiated from the light source to the document.
An electrophotographic duplicator characterized in that a recording/receiving light-receiving element is disposed in a position that moves along the light source, and means is provided for detecting the intensity of the light while the light-receiving/receiving element moves during copying. How many dimmers.