JPH0412503Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a correction device that automatically controls the exposure amount during diazo printing using a simple multiplication/division circuit.

Generally, when using a diazo copying machine, if you want to give the photosensitive sheet an appropriate amount of printing exposure in response to the light transmittance of original sheets with different transparency, it is best to quickly and manually adjust the light sensitivity of the photosensitive sheet. Light emitted from a projector or an exposure light source is applied to the original sheet directly or through a light pipe typified by an optical fiber, and the amount of printing exposure is automatically controlled based on the photoelectric output of the amount of transmitted light. Various types of printing exposure control devices have been proposed, each of which is based on a complex logic circuit or a microcomputer with an analog/digital switch.

However, because these devices incorporate various functions, they are troublesome in terms of creating and manipulating memory data, and they are surprisingly expensive in terms of cost, resulting in a lack of widespread use. In addition, the amount of light that cannot be predicted may be due to dirt or dust that accumulates on the surface of the exposure light source lamp, the inner or outer surface of the cylinder glass for printing, the input/output end face of the light pipe, the surface of the dedicated emitter/receiver, or contamination of the developer. If this fluctuation occurs, the actual light transmittance corresponding to the original sheet will be distorted, and there is a possibility that proper printing exposure may not be performed. In such cases, the current situation is to correct the problem by manual adjustment or mechanical removal using a felt cleaner, suction air cleaner, etc. Therefore, the present invention has been developed so that even if a diazo copying machine that always uses paper or synthetic paper, etc., which requires various degrees of transparency as original sheets, is affected by dirt, dust, etc., the sheet passage path upstream of the exposure section can be The multiplier value of the photoelectric voltage of the sheet, which is derived from the amount of transmitted light corresponding to the material of the original sheet by the provided light emitter and receiver, and the photoelectric voltage of the exposure source, which is guided through the cylinder glass of the exposure section, is calculated when the document is placed in the sheet passage path. To provide a correction device that automatically corrects the amount of light for printing on a photosensitive sheet using a correction output obtained by dividing the amount of light emitted when there is no sheet by the photoelectric voltage without a sheet. be.

In addition, the present invention uses a two-element cadmium sulfide photoconductive resistor photocoupler and a two-element cadmium sulfide photoconductive resistor to compensate for the appropriate printing exposure amount for the photosensitive sheet in response to the light transmittance of original sheets with different transparency. It is an object of the present invention to provide an automatic correction device for diazo burning which has very good calculation accuracy and is economically cheaper by embodying a simple and easy-to-understand multiplication/division circuit consisting of two operational amplifiers.

Embodiments of the present invention that achieve these objects will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a related system of an automatic correction device for diazo printing exposure.

Reference numeral 1 denotes a sheet passing path that leads to the insertion slot and guides the sheet to be inserted, and is provided to give the photosensitive sheet an appropriate amount of exposure by obtaining an amount of transmitted light corresponding to the material of the sheet. .

Reference numeral 2 denotes an exposure section disposed downstream of the sheet passage path, and in the exposure section 2, a cylinder glass 4 containing an exposure source 3 performs proper exposure using an endless belt or the like that synchronizes with the conveyance speed of the sheet. The stack of photosensitive sheets is rotated in proportion to the amount of light, and the stack of photosensitive sheets is brought into close contact with the original that reaches the outer peripheral surface of the cylinder glass 4, and this stack is irradiated with the light beam of the exposure source 3 from the original side. be. In the sheet passing path 1, there is a dedicated flood light source 5 (in the illustrated example, an incandescent miniature lamp) provided so that light crosses this path and obtains a transmitted light rate corresponding to the material of the sheet. A light receiving sensor 6 (in the illustrated example, a photodiode) receives the light flux when the power is turned on.
When the sheet is not inserted into the passageway or the inserted sheet has not yet reached the light receiving sensor 6, the sensor 6 receives the same amount of light emitted from the light source 5, and when the sheet is guided and blocks the sensor 6. Two light receiving paths are formed in which the sensor 6 similarly receives the amount of transmitted light corresponding to the material of the sheet.

There, the amount of light received by the light receiving sensor 6 is converted into a current, passed through an amplifier circuit 7, further converted into voltage, and applied to the automatic correction device 8. The automatic correction device 8 first makes the voltage conductive to the first sample-and-hold circuit 9 and the second sample-and-hold circuit 10. 1st
The sample and hold circuit 9 synchronizes with the sheet conveyance speed using a reset signal 11 that is emitted at the same time as the power is turned on or a sheet detection signal 12 that is emitted when the rear end of the sheet inserted into the sheet passage path 1 leaves the light receiving sensor 6. Based on the timing signal _S1 transmitted through the timing circuit 14 operated by the clock signal 13, the photoelectric voltage in the state where there is no inserted sheet in the previously given sheet passage path is held and the output is _V1 . put out. In the second sample and hold circuit 10, a timing signal is generated via a timing circuit 14 in response to a sheet detection signal 12 generated when an inserted sheet blocks the light receiving sensor 6 in the sheet passage path.
Based on _S2 , the photoelectric voltage corresponding to the amount of transmitted light corresponding to the material of the insertion sheet is held and outputted as an output _V2 . These hold voltages V ₁ and V ₂ are then applied to the next multiplication/division circuit 15 . In the multiplication/division circuit 15, the light flux emitted from the exposure source 3 of the exposure section 2, which forms another photoelectric path, is detected by a light receiving sensor 16 (in the illustrated example) disposed at a suitable location near the outer peripheral surface of the cylinder glass 4. , a photodiode), a photoelectric voltage V ₃ corresponding to the luminous flux of the exposure source 3 is applied through the receiving and amplifying circuit 17, and the following arithmetic processing is performed to obtain a corrected output V ₀
Calculate.

V ₀ = _{K × V 2} Even if there is contamination with developer or developer, the value indicated by symbol K is constant because the output V ₁ without the inserted sheet and the output V ₂ with the inserted sheet are obtained under the same conditions, so it is appropriate. It is taken out as an output, and consideration is also taken to correct for the attenuation of the optical power of the exposure light source over time, dust and liquid contamination adhering to the inner and outer surfaces of the cylinder glass. Therefore, when this correction output is temporarily applied to the control servo motor, the speed of the drive motor is changed to the appropriate photosensitive sheet printing speed corresponding to the light transmittance of the inserted sheet, and the diazo printing exposure amount is automatically adjusted. It is corrected.

FIG. 2 is a block diagram showing another embodiment of the automatic correction device.

108 is an automatic correction device, 109 is a first sample and hold circuit, 110 is a second sample and hold circuit, 113 is a clock signal synchronized with the conveying speed of the sheet, 114 is a timing circuit, and 115
indicates a multiplication/division circuit, 112 is a detection signal,
In this case, a signal is generated when the leading edge of the inserted sheet is detected by another detection unit in the sheet passage path, and then a signal is generated when the inserted sheet blocks the light receiving sensor by a dedicated emitter/receiver. . For example, when the inserted sheet pushes up the feeler of the sheet detection sensor and generates the sheet detection signal 112,
The timing circuit 114 sends a timing signal S ₁ ', which enters the first sample and hold circuit 109 and holds the output V ₁ ' of no sheet. after that,
When the insertion sheet completely blocks the light receiving sensor, the output V ₂ ′ corresponding to the amount of light transmitted by the insertion sheet, V ₃ ′ which is proportional to the brightness of the exposure light source lamp, and the hold output V ₁ ′ without the insertion sheet, are as follows. The receiving multiplication/division circuit 115 performs arithmetic processing. This output V ₀ ' is simultaneously outputted via the timing circuit 114 as S ₂ '
This timing signal is held in the second sample hold circuit 110 and used as a correction output to appropriately control the diazo printing exposure amount.

FIG. 3 is a wiring diagram showing a simplified multiplication/division circuit in the automatic diazo printing exposure correction device of the present invention.

Reference numeral 15 is a multiplication/division circuit, and 18 is a photocoupler formed by two (or two elements) cadmium sulfide photoconductive resistors (CdS) 19, 19' and a light emitter (here, a photodiode LED) 20. It is.

On the other hand, the CDS 19' has an insertion sheet as a sheet passage path indicated by the symbol _V2 , receives the light beam from a dedicated light projecting source, receives the photoelectric voltage derived from the amount of transmitted light corresponding to the material of the insertion sheet, and the output is It is connected to the negative input terminal (or inverting input terminal) of the first operational amplifier (abbreviated as operational amplifier) 21, and the positive input terminal (or non-inverting input terminal) of the first operational amplifier 21 is grounded. Other CdS
Reference numeral 19 receives a negative photoelectric voltage that is guided by directly receiving the luminous flux of the dedicated light projecting source when there is no inserted sheet in the sheet passage path indicated by symbol V ₁ , and its output is connected to the negative input terminal of the second operational amplifier 22. The positive input terminal of the second operational amplifier 22 is grounded. The positive photoelectric voltage derived from the luminous flux of the exposure source, indicated by the symbol V ₃ , is resistive.
It is connected to the negative input terminal of the second operational amplifier 22 through _R1 . The output terminal of the second operational amplifier 22 is connected to an LED 20 via a resistor _R3 , and the LED 20 is connected to a positive power supply Vcc for operating the multiplication/division circuit. A resistor of R ₂ is arranged between the input-side negative terminal and the output-side terminal of the first operational amplifier 21, and the correction output from the analog multiplier/divider circuit indicated by the symbol V ₀ is taken out from the output-side terminal of the first operational amplifier 21. The wiring for operating the operational amplifier is omitted. The operation of this connection diagram will be explained as follows.

The voltage of (-)V ₁ is applied to the negative input terminal of the second operational amplifier 22 via the resistor R _A of the CdS 19, and the voltage of (+) V ₃ is similarly applied to the second operational amplifier 22 via the resistor R ₁ . When applied to the negative input terminal of the operational amplifier, due to the characteristics of the operational amplifier and the ground connection at the positive input terminal, the point at the negative input terminal becomes imaginary ground, so it becomes zero potential, and the resistance R increases with respect to the voltage V ₃ . The current I ₂ flows into the point via ₁ and we get the following equation.

I ₂ =V ₃ /R ₁ ...Then, current I ₁ flows out from the point via resistor R _A of CdS 19 with respect to voltage V ₁ to obtain the following equation.

−I ₁ = V ₁ /R _A ... Since no current other than currents I ₁ and I ₂ enters or exits the point, CdS19 is such that the currents I ₁ and I ₂ are equal.
The output voltage of the second operational amplifier 22 is controlled via the resistor _R3 to obtain the resistance R _A of the light emitter 20.
Make the LED emit light. From the point where the current I ₁ = I ₂ , the following equations and are obtained.

V ₃ /R ₁ = -V ₁ /R _A ... R _A = -V ₁ /V ₃・R ... The resistor R _B of CdS19' naturally emits exactly the same amount of light as the LED of the projector 20. Since it is irradiated, the above R _A
It shows a resistance value similar to that of . The calculation accuracy of this multiplication/division circuit depends solely on the same accuracy of the rate of change in resistance with respect to the current of the CdS, but the results of product inspection were extremely good, and the following equation holds true. The variation between the two elements represented by the symbol α expressed by the following equation is in the range of 0.7<α<1.3.

R _B =αR _A ... Since the first operational amplifier 21 is connected to an inverting amplification circuit, the output voltage V ₀ is given by the following equation.

V ₀ =−R ₂ /R _B ·V ₂ ... By substituting the above equation into the equation, the corrected output V ₀ of the following equation is obtained.

V ₀ =1/α・R ₂ /R ₁・V ₂・V ₃ /V ₁ ...Therefore, it is a simplified multiplication/division circuit that is simpler and clearer than the conventional one, and its calculation accuracy is as good as it is. Therefore, it can be provided as an economically cheaper product.

FIG. 4 is a wiring diagram showing another operation of the multiplication/division circuit according to the present invention.

115 is a multiplication/division circuit, 118 is two CdS
A photocoupler formed by photoconductive resistors 119, 119' and a light emitter (here, an incandescent pilot lamp) 120; 121 is a first operational amplifier;
2 is the second operational amplifier, 123 is the second operational amplifier 1
This is a current control circuit provided to increase the output of the projector 22 to ensure the amount of light emitted from the projector 120. Symbols V ₁ ′, V ₂ ′, and V ₃ ′ are inputs provided to this multiplication/division circuit, and the input of V ₁ ′ is given as positive, and the input of V ₃ ′ is given as negative. Symbols R ₄ , R ₅ , R ₆ are resistances, and in the example shown
In particular, the resistance R ₆ is formed to be variable, so that variations between two elements in the CdS photoconductive resistor described above in the multiplication/division circuit can be easily adjusted.

The symbol V _EE is the negative power supply applied to the pilot lamp 120, R _C and R _D are the resistances of each CdS, the current I ₃ flows to the imaginary earth point via the resistor R _C , and the current I ₄ flows from the resistor point to the imaginary earth point. It is designed to flow out via R ₄ . The symbol V ₀ is the corrected output given by the following equation.

V ₀ ′=1/β・R ₅ +R ₆ /R ₄・V ₂ ′・V ₃ ′/V ₁ However, in this illustrated example, the projector is an incandescent lamp, so a measure to improve the heat dissipation mechanism was taken. Must be considered.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the related system of the automatic correction device for diazo printing exposure amount, Fig. 2 is a block diagram showing another embodiment of the automatic correction device, and Fig. 3 is the automatic correction device for diazo printing exposure amount of the present invention. A wiring diagram showing a simplified multiplication/division circuit in the correction device. FIG. 4 is a wiring diagram showing another operation of the multiplication/division circuit in the present invention. DESCRIPTION OF SYMBOLS 1...Sheet passage path, 2...Exposure section, 3...Exposure source, 4...Cylinder glass, 5...Dedicated light emitter source, 6...Light receiving sensor, 8, 108...Automatic correction device, 9,109...First sample hold circuit, 10,110...Second sample hold circuit, 12,112...Sheet detection signal, 13,1
13... Clock signal synchronized with sheet conveyance speed, 14, 114... Timing circuit, 15, 1
15...Multiplication/division circuit, 16...Light receiving sensor, 1
8,118...Photocoupler, 19,19',1
19,119'...Cadmium sulfide photoconductive resistor,
20,120...Projecting body, 21,121...First
Operational amplifier, 22, 122...Second operational amplifier.

Claims (1)

[Scope of claim for utility model registration] In a diazo copying machine that automatically controls the printing exposure amount of a photosensitive sheet in accordance with the light transmittance of original sheets of different transparency, in the sheet passage path upstream of the exposure section. A first photoelectric voltage derived from the amount of light emitted by the light emitting and receiving sensor in a state where there is no document sheet; and a second photoelectric voltage derived from the amount of transmitted light corresponding to the material of the document sheet in the sheet passage path by the light emitting and receiving sensor. and a third photoelectric voltage obtained from the light receiving sensor of the exposure source through the exposure sources and the cylinder glass in the exposure section, and the multiplication value of the second photoelectric voltage and the third photoelectric voltage by the first photoelectric voltage. a multiplication/division circuit for dividing; the multiplication/division circuit includes a photocoupler including a two-element cadmium sulfide photoconductive resistor and a light emitter; a first operational amplifier; and a second operational amplifier; is applied to one element of the cadmium sulfide photoconductive resistor along with a third photoelectric voltage.
The light emitter is turned on through the inverting input and output of the operational amplifier, and the second photoelectric voltage is passed to the other element of the cadmium sulfide photoconductive resistor to obtain the output voltage obtained by the inverting amplification of the first operational amplifier. Diazo burn-in automatic correction device using a simple multiplication/division circuit for correction output.