KR920000821B1 - Automatic manuscript brightness sensing apparatus - Google Patents

Abstract

The method detects the density of the original print utilizing a simple apparatus to allow the high quality of the duplicated from the first page. The detector includes a permanent magnetic (MG) deposited at the edge of the cover, a contactless sensor (B) connected to a power terminal for generating on/off signal according to the distance to the permanent magnet, a photo interrupter unit (A) including a light emission device and a light receiving device, and a comparator (C) for comparing the voltage of output signal of the light receiving device with reference voltage input through a resistors (R3,R4) connected to the contactless sensor and ground. The light emission device has a variable resister on the output terminal.

Description

Automatic Document Density Detection Device

1 is a schematic structural diagram of a copying machine to which the present invention is applied.

2 is a structural diagram of a document density sensor according to the present invention.

3 is a circuit diagram showing the overall configuration of the present invention.

4 is a flowchart illustrating the operation of the copier to which the present invention is applied.

* Explanation of symbols for the main parts of the drawings

11: Original density sensor 12, B: Proximity sensor

13, MG permanent magnet 14,28 Contact glass surface

15,27: white board 16: platen

21: blanket 24: sensor holder

25: light emitting diodes 26: phototransistor

29 Original A: Photo interrupter

C: comparison unit d: concentration control unit

R: Resistance D: Light Emitting Diode

TR: Phototransistor VR: Variable resistor

C1: condenser

The present invention relates to an automatic document density detection device in a plain paper copying machine, which automatically detects the density of an original to always provide a clear and clear copy quality.

In the conventional case, in order to improve the image quality of the copy and to eliminate the inconvenience of adjusting the density at each copy, the AE (Auto Exposure) function is added to the copier to fix the original on the contact glass and to expose the first copy. Irradiation of light onto the document through an exposure lamp, and a portion of the reflected light is detected using a photo diode to detect a photocurrent corresponding to the reflected light, and a comparison is performed using a comparator. By measuring the contrast of the document, the contrast of the copy was adjusted. However, the conventional method has the disadvantage that it is not always possible to control the density of the first copy and to require a complicated mechanical device for the AE function.

The present invention has been conceived to solve the above problems, and does not require a complicated mechanical device, and provides an automatic document density detection device that can perform a clear density adjustment from the first document to obtain a clear image from the first copy, without requiring a complicated mechanical device. In order to achieve the above object, the present invention provides a permanent magnet attached to the edge of the platen, and a proximity sensor means connected to a power supply terminal and performing OFF and ON operations according to the perspective position of the permanent magnet, and the proximity A photo interrupter means connected to the sensor means and including a light emitting element and a light receiving element, an output terminal of the light receiving element of the photo interrupter means and the proximity sensor means, the output voltage of the light receiving element and the proximity Compare the reference voltage provided by the resistor connected to the sensor means and the resistor connected to ground. It consists of a comparison means for alternately outputting.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a perspective view showing a schematic structure of a copier to which the present invention is applied, in which 11 is an original density sensor, 12 is a proximity sensor, 13 is a permanent magnet, and 14 is a contact glass surface. 15 denotes a white board and 16 denotes a press board.

As shown in the drawing, the copier to which the present invention is applied is provided with an original density sensor 11 and a permanent magnet 13 on the platen 16, and a proximity sensor 12 is installed on the upper part of the main body corresponding to the permanent magnet. When the user puts the document on the contact glass surface 14 and closes the platen 16 so that it does not move, the permanent magnet 3 attached to the platen 16 is in close proximity to the proximity sensor 12. The power is applied to the document concentration sensor 11 by the operation (ON) to perform the operation.

2 is a structural diagram of a document concentration sensor according to the present invention, where A is a perspective view of the document concentration sensor and B is a cross-sectional view of the document concentration sensor.

In the perspective view (A), 21 is a blanket, 22 is a contact surface of the blanket and the white board, 23 is a sensor wiring, and in the cross-sectional view, 24 is a sensor holder, 25 is a light emitting diode, 26 is a photo transistor, and 27 is a white board. , 28 are contact glass surfaces, 29 are originals θ represent reflection angles, respectively.

As shown in the figure, the photointerrupters (light emitting diodes and photo transistors) 24, 25, and 26 of the original concentration sensor according to the present invention use the sensor blanket 21 to reflect the reflected light sufficiently. When the power is applied to the photointerrupter, the light emitting diode 25 irradiates light onto the original 29, and the irradiated light strikes the original surface and is reflected at the reflection angle θ. The reflected light is made incident on the base terminal of the photo transistor 26.

3 is a circuit diagram showing the overall configuration of the present invention, in which A is a photo interrupter, B is a proximity sensor, C is a comparator, d is a concentration control, MG is a permanent magnet, and R is Resistor VR is a variable resistor, C1 is a capacitor, D is a light emitting diode, and TR is a transistor.

As shown in the drawing, the present invention arranges a proximity sensor B that performs OFF and ON operations according to the perspective position of the permanent magnet MG at a power supply, and emits a light emitting diode D and a light receiving transistor TR. A photo interrupter (A) is connected to the proximity sensor (B), a resistor (R1) is connected to the light emitting diode (D) of the photo interrupter, and a variable resistor (VR) is applied to the phototransistor (TR) of the photo interrupter. ) Is connected to the resistor (R2) connected in series with the capacitor (C1) connected in parallel to the two resistors (R2, VR), and to the proximity sensor (B) to make a reference voltage of the comparator (C) A resistor R3 connected in series with R4 is connected, and the comparator C receives a voltage VR4 applied to the resistor R4 to an inverting input terminal (-terminal) and a non-inverting input terminal (+ terminal). The OP AMP is connected to be configured to input voltages applied to the two resistors R2 and VR, and the output terminal of the comparison unit C The configuration to connect the control unit (d). The present invention configured as described above operates as follows. When the original is placed on the contact glass and the platen is closed, the permanent magnet (MG) attached to the platen operates the proximity sensor (B) to supply power to the photointerrupter (A), and the photo interrupter The light emitting diodes D are turned on to irradiate light onto the document. The irradiated light hits the original surface and is reflected, and the reflected light is incident on the base terminal of the photo transistor T of the photo interrupter, and according to the intensity of the incident light, the magnitude of the voltage applied to the positive input terminal of the comparator is increased. Will change.

In addition, based on the voltage (V _R4 ) applied to the R4 resistor input to the OP AMP (-) terminal of the comparison unit (C) as a reference to compare the voltage coming into the (+) input terminal is output to the concentration control unit (d). The output of the OP AMP changes according to the density of the original background.

If the background of the original is a white paper, that is, when the light reflected from the original is strong, the variable input VR is adjusted so that the output of the OP AMP appears so that the inverting input side of the OP AMP indicated by the resistor R4 appears. Make it larger than the (-side) voltage. On the other hand, if the background of the original is black pulp paper or colored paper, the reflected light is weak so that the output of the OP AMP does not appear so that it does not affect the density control part (d) of the next stage. Therefore, the density controller d can automatically adjust the density of the copy by using the magnitude of the input voltage.

4 is a flowchart showing the operation procedure of the copying machine to which the present invention is applied. The copying procedure of one original is as follows. When the original to be copied is set to the size of the contact glass, and (41) closes the platen so that the original does not move (42), the proximity sensor is turned on (43) and power is supplied to the photo interrupter. (44) The comparison unit compares the output terminal voltage and the reference voltage of the photo transistor input to the OP AMP and outputs the output (45). The density controller controls the image density of the copy using the output voltage of the OP AMP (46). A copy of image quality is provided (47).

The effect of using the present invention is that, as in the conventional case, a complicated mechanical device for implementing the AE (Auto Exposure) function is unnecessary, and the first density of the copy can be automatically adjusted to obtain a clear image from the first chapter. Can be mentioned.

Claims (5)

Permanent magnet (MG) attached to the edge of the platen and the proximity sensor means connected to the power supply in order to detect the density of the original to improve the image quality of the copy and performs OFF, ON depending on the perspective position of the permanent magnet (B), a photo interrupter means (A) connected to the proximity sensor means and including a light emitting element and a light receiving element, and an output terminal of the light receiving element of the photo interrupter means and the proximity sensor means; Input to the inverting input terminal (-terminal) by the voltage inputted to the non-inverting input terminal (+ terminal) by the output of the light-receiving element, the resistor R3 connected to the proximity sensor means and the resistor R4 connected to ground. Automatic document density detection device, characterized in that consisting of the comparison means for comparing and outputting the reference voltage. The apparatus of claim 1, wherein the proximity sensor means (B) of FIG. 1 is installed on an upper portion of the main body at a position corresponding to the permanent magnet (MG) attached to the platen. The document concentration detection sensor (11 in FIG. 1) including the photo interrupt means (A) is attached to a white board on a platen so that the front surface thereof is flat. Automatic document density sensing device. The automatic document density sensor according to claim 1 or 3, wherein the photo interrupter of the document density sensor is mounted as high as the angle of reflection (θ) using a sensor blanket so that the reflected light can be sufficiently incident. 2. The automatic document density sensing device according to claim 1, wherein the output terminal of the light receiving element of said photo interrupter means (A) comprises an adjustable variable resistor (VR).

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