JPS61121069A - Automatic exposure device - Google Patents

Abstract

PURPOSE:To obtain always good copies without influences of the copy magnification, the original size, the copy size, etc. by detecting the density of only a part to be copied of an original placed on an original glass. CONSTITUTION:A density sensor SE2 is surrounded with a hood 21 which shields light from peripheral parts and has the light reception angle adjusted by a pair of control members 22 and 22 which are freely protruded to and drawn black from an aperture part of the hood 21. Control members 22 and 22 are freely moved along guide rails 23, and gear parts 22a and 22a are formed in their lower edges and are engaged with helical shafts 24 and 24 driven by motors M and M. Motors M and M are rotated in the same direction synchronously with each other by a CPU100 of a control circuit, and the vertical between control members 22 and 22 is changed to set the light reception angle of the density sensor SE2 to a proper value. Thus, the reflected light from an area other than the area to be copied of the original is not made incident on a light receiving means.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic exposure device for an electrophotographic copying machine, and more specifically, the present invention relates to an automatic exposure device for an electrophotographic copying machine. The present invention relates to an automatic exposure device that can perform exposure of large amounts of light.

In order to prevent such copying errors, a device equipped with an automatic exposure device that automatically determines the exposure amount according to the density of the original has been proposed.

The above device is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-29060, 57
As disclosed in Japanese Patent No. 124373, etc., a sensor detects the density of a part or the entire document placement area, and the output of an exposure lamp is adjusted in accordance with the output of the sensor.

However, in general, the density of copied originals is not uniform, and the degree of a varies greatly depending on the part, so it is possible to detect the density of a part of the original and control the output of the exposure lamp based on that density. In this case, a copied image with good density cannot be obtained.

Further, in a device that detects the density of the entire surface of the document placement area, it also detects the density of documents other than those actually placed. For example, when a small document is placed in the document placement area and the document cover is closed, the document may be detected to be lighter than it actually is due to the effect of the white back surface of the document cover.

An object of the present invention is to provide an automatic exposure apparatus that solves the above-mentioned problems.

Means for Solving the Problems As a means for solving the above-mentioned problems, an automatic exposure apparatus according to the present invention illuminates the original placed on the original placing table H with an illumination means and receives the reflected light. detecting the illumination by the illumination means, and changing the amount of illumination light from the illumination means based on the detection signal,
In an automatic exposure device designed to keep the density of a copied image constant, 1. A regulating means for regulating the light receiving angle of the light receiving means;
A supporting means for movably supporting the regulating means to change the light receiving angle thereof; a document size detecting means for detecting the document size; a copy paper size detecting means for detecting the copy paper size; a copying magnification detection means for detecting a copying magnification, a calculating means for calculating a copying area on the document mounting table from the copying magnification and copying paper size, and a calculation means for calculating a copying area on the document table from the copying magnification and copying paper size; a first control means for moving the regulating means supported by the support means so that the angle corresponds to the copying area; and when the copying area is larger than the original size, the light receiving angle of the light receiving means is adjusted to the original size; and second control means for moving the regulating means supported by the supporting means so as to form a corresponding angle.

According to the automatic exposure device configured as described above, when the original size, copy paper size, and copying magnification are set, the light receiving angle of the light receiving means is set to the maximum angle corresponding to the original size, and the angle corresponding to the original size is set as the maximum. is set to an angle corresponding to Therefore, reflected light from areas other than the copying area of the document does not enter the light receiving means.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the vicinity of the optical system of a copying machine equipped with an automatic exposure device according to the present invention, in which (1) is an original glass, and (2) is an original that presses the original (0) onto the original glass (1). It is a crimp plate. A document glass (1) is attached to the pressure bonding surface of the document pressure bonding plate (2) in cooperation with a size movement sensor (SEL) described later.
The length O perpendicular to the scanning direction of the original (0) placed above
x) (hereinafter referred to as the width of the document) is provided with an LED array (L) (see FIG. 3).

On the other hand, the scanning optical system (3) disposed on the lower surface of the document size (1) is connected to an illumination lamp (4) that moves and scans to the left in the figure.
), a size sensor (SEL) that is provided above the illumination lamp (4) and detects the width of the document by receiving the light emitted from the LED array (L) (see FIG. 4); ), which moves and scans in the same direction and at the same speed.
a mirror (5), second and third mirrors (6) that move in the same direction as the first mirror (5) and at half the speed;
7), a projection lens (8) that moves in the direction of its optical axis according to the copying magnification, and a projection lens (8) that receives reflected light from the original illuminated by an illumination lamp (4) provided adjacent to the projection lens (8); It is composed of an AT sensor (SC2) that detects the original density and a fixed fourth mirror (9), and
At the same time, the document image is projected onto the photoreceptor drum (l).

As shown in FIG. 5, the concentration sensor (SC2) is surrounded by a hood (21) that blocks light from the surroundings, and has a pair of movable sensors installed in the opening of the hood (21). The light receiving angle can be adjusted by the regulating members (22), (22).

As shown in FIG. 6, the regulating member (22) (22) is provided movably along the guide rail (23), and has a gear portion (22a) (22λ
) is formed and meshes with a helical shaft (24) (24) driven by motors (c) and H. Motor (b)
(b) are rotated in the same direction in synchronization with each other by (, PU (100) of a control circuit (described later), and the regulating member (
22) By changing the interval of (22), the concentration sensor (SE
2) Set the acceptance angle to an appropriate value.

Furthermore, the copying machine is equipped with a known copy paper size detection means, which is not shown in the drawings. This is, for example, JP-A-54
As shown in Japanese Patent No. 126364, the copy paper size may be detected using a protrusion provided on the paper feed cassette and a microswitch operated by the protrusion, or a magnet and a lead may be used to detect the copy paper size. It may also be detected by a switch.

FIG. 7 is a block diagram schematically showing the configuration of a microcomputer that controls the copying machine, and (100) is a C
In the PU, its input boat includes a document size detection means (1) including an LED array (L) and a size sensor (SEI).
01), copy paper size detection means (102) including a micro switch or reed switch, and dense magnification input means (
104) is connected. On the other hand, the output port has a regulating member (
22) Drives the motor drive circuit (105) containing 1M (to the motor that moves (22)), the lamp drive circuit (106) containing the illumination lamp (4), and the scanning optical system (3). A scan drive circuit (107) and a magnification display means (108) for displaying the copy magnification input manually are connected.

The microcomputer executes each process according to the procedure shown in the flowchart of FIG.

That is, when the copying machine is powered on, initial settings are executed in step SO. In this step, the variable items of the copying machine are set to the initial state, for example, the copy number display is set to 1, and the copy magnification is set to 1x. Furthermore, in this step, the scanning optical system (
3) is not at the initial position (PG) (see Figure 2), force the scanning optical system (3) to return to the initial position (PO).

In step S1, it is determined whether a copy command has been input by turning on a print key (not shown), and when the print key (not shown) is turned on, the process proceeds to step 52 and subsequent steps.

In step S2, move the scanning optical system (3) at the initial position to a position (Pl) where the original size can be detected. In this position, the LED provided on the document cover (2)
The size sensors (SE2) provided on the illumination lamps (4) of the array (L) are in a state of facing each other.

In step S3, the LεD array (L) is turned on, and the size sensor (SEL) reads the state in which the light emitted by the corresponding ED array υ is blocked by the original (0), and the width (Ox ) is detected. After detecting the width, return the scanning optical system (3) to the initial position (PO).

In step S4, the width (Cx) and length (Cy) of the copy paper being fed are detected.

In step S5, the copy magnification (b) manually entered by the key is detected.

In step S6, the width of the document (Ox) and the width of the copy paper (Ox) are determined.
Cx ) and copying magnification (b), the density sensor (S
Execute the process of changing the light receiving angle (0) of E2).

Details of the processing in this step are shown in FIG. 1(b).

In step 7, the illumination lamp (4) is turned on to cause the scanning optical system (3) to scan. The scan length shall be the value obtained by dividing the width (Cy) of the copy paper being passed by the copying magnification (B), that is, C77M. Further, the output of the illumination lamp (4) is successively varied during scanning according to the density of the original detected by the density sensor (SE2), and as a result, the density of the copied image can be made uniform.

In step S8, it is determined whether or not scanning of a predetermined number of copies has been completed. If not, step S7 is repeatedly executed until the predetermined number of copies is reached.

FIG. 1(b) shows details of the light-receiving angle control subroutine, and in step 561, the width of the copying area (0'x) is calculated from the copy paper width (Cx) and the copying magnification (b). do. The area to be copied is the quotient divided by the copy paper size (q to copy magnification), that is, C7M. Specifically, it is an area on the original glass (1) that can be copied onto a passing copy sheet, or an area to be copied. For example, when a copy sheet of A3 size is passed through at a copying magnification of 1.41 times, the area to be copied is A4 size, which is the size of A3/1.41.

In step 562, the width (Ox) of the original (0) is compared with the width (0'x) of the area to be copied, and the width (Ox) of the original (0) is compared with the width (αX) of the area to be copied. ), the process proceeds to step 563 and the concentration sensor (S
The motors (b) and (b) are driven so that the light receiving angle (θ) of C2) is set to an angle corresponding to the width (0'x) of the copying area. On the other hand, when the width (Ox) of the original (0) is smaller than the width (0'x) of the copying area, the process proceeds to step 364, and the light receiving angle of the density sensor (SC2) is set to the width of the original (0). (
The motor (C) is driven to make the angle corresponding to (Ox).

The processing of the light reception control subroutine described above will be better understood and explained using FIG.

Figure 8(a) shows an A3-sized document placed on glass (1).
This example shows a case where originals of 4 sizes are placed, the copy magnification is 0.707 times, and the copy paper size to be passed is A4 size. In this case, the entire area of the A3 size document glass (1) becomes a copy area that can be copied onto copy paper.

In the above case, the width (0'x) of the area to be copied in step 561 is 0'x = 21010.707 = 29'711+
It is calculated as I (A 3 size (7) width). and,
In step S62, the width (Ox) of the document (0) is compared with the width (0'x) of the area to be copied, and since Ox = 210 m and O'x = 297 + m, Ox (0'x is determined, and the process proceeds to step 564, where the concentration sensor
The light receiving angle (θ) in 2) should be set to an angle corresponding to the width of the original (0) (7) width (Ox) of the A4 size document (210+m). Therefore, the density sensor (SC2)
Since only the reflected light from the blank area is received and the reflected light from other blank areas is not received, the density of the document (0) can be accurately detected without being affected by the density of the blank area.

On the other hand, FIG. 8(b) shows a case where an A4 size document (0) is copied onto A5 size copy paper at a copying magnification of 1.0.

In the above case, the width (0'x) of the area to be copied in step 561 is 0'x - 148/1.0 = 148 m (A
5 size width). And step 56
In 2, the width (Ox) of the original (0) is compared with the width (0'x) of the area to be copied, and since 0'X = 210 m and O'X = 148 m, Ox ) 0' x, and the process proceeds to step 564, where the a degree sensor
The light receiving angle (θ) in 2) is set to an angle corresponding to the width (0'x) of the area to be copied, that is, the width 148 of the size 5. Therefore, the density sensor (SC2) receives only the reflected light from the area to be copied (the area surrounded by the dotted line in the figure) of the original (0), and does not receive the reflected light from other parts, so it cannot be copied. The density of the original in the area to be copied can be accurately detected without being affected by the density of the original (0) in the area that is not copied.

The automatic exposure control device of the present invention uses the density sensor f (SC2) not only in the above two cases but also in any combination of copy magnification, document size, and copy paper size.
The acceptance angle (θ) of is set to the optimum value.

Furthermore, although in the above embodiment, the document density was measured sequentially during scanning, a pre-scan was performed to measure the document density prior to the main scan, and the document density was measured based on the document density data measured at that time. It may also be used to determine the exposure song during the main scan.

Effects of the Invention As is clear from the above explanation, the automatic exposure apparatus according to the present invention can detect the density of only the portion of the document placed on the document glass that is to be copied. The optimum illumination brightness is provided according to the situation, and good copies can always be obtained without being affected by copy magnification, original size, copy paper size, etc.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing the operation procedure of the automatic exposure device according to the present invention, Fig. 2 is a diagram schematically showing the configuration of the scanning optical system of the copying machine and its vicinity, and Fig. 3 is a diagram showing the opening of the document pressure plate. FIG. 4 is a perspective view of the illumination lamp, and FIG. 5 is a configuration diagram of the part where the concentration sensor is attached, and shows how the acceptance angle changes as the regulating member moves. 6 is a front view showing the support mechanism of the regulating member, FIG. 7 is a circuit diagram, and FIG. 8 is a diagram for explaining how the light receiving angle is changed. (1)...Original glass, (2)...Original pressure bonding plate, (
22)...Regulation member, (100)-CPU, L
,,, L E D 7 tzi, SE2...1 degree sensor. Applicant Minolta Camera Co., Ltd. Figure 1 (a) Figure 1 (b) Figure 5 Figure 7 Figure 8 ((1) Figure 3 (b)

Claims (1)

[Claims] 1. A document placed on a document table is illuminated by an illumination means, the reflected light is detected by a light receiving means, and the amount of illumination light from the illumination means is changed based on the detection signal. , an automatic exposure apparatus configured to maintain a constant density of a copied image, comprising: a regulating means for regulating a light-receiving angle of the light-receiving means; and a support means for movably supporting the regulating means and making it possible to change the light-receiving angle. , an original size detection means for detecting the original size; a copy paper size detection means for detecting the copy paper size; a copy magnification input means for inputting a copy magnification; a calculation means for calculating a copy area;
a first control means for moving the regulating means supported by the supporting means; when the area to be copied is larger than the original size, the light receiving angle of the light receiving means is an angle corresponding to the original size;
An automatic exposure apparatus comprising: second control means for moving the regulating means supported by the support means.