JPH01254063A - image succession device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in facsimile machines, copying machines, etc.
The present invention relates to an image reading device that reads images written on a manuscript or the like.

[Prior Art] This type of image reading device usually illuminates the document surface with a light-emitting element, receives reflected light from the document surface with a light-receiving element, and reads an image on the document surface based on the amount of received light. It has become.

In this device, the reading characteristics are not constant due to variations in or changes in the characteristics of the optical system including the light emitting element and the light receiving element, as well as manufacturing errors, resulting in inaccurate image reading. It is necessary to adjust the amount of light emitted by the light emitting element to keep the reading characteristics constant.

For this reason, conventional image reading devices have a reading head that has a light emitting element that emits illumination light to illuminate the document surface, and a light receiving element that receives reflected light from the document surface and generates a signal according to the amount of light received. , is arranged so as to be able to approach and separate from the reading head, is biased toward the reading head, contacts the original from the side opposite to the reading head, cooperates with the reading head, supports the original, and supports the reading head. A document holding member has a recess formed on a surface facing the recess, and a reference reflective surface having a predetermined reflectance is provided on the bottom of the recess, and a signal corresponding to the amount of light received by the light receiving element is detected and converted into image information. A light emitting drive means that causes a light emitting element to emit light at a specified amount of light, and a control means that performs data processing and various controls for image reading. The light emission amount of the light emitting element is adjusted so that the detection means outputs predetermined image information by reading the reflective surface, and the adjusted light emission amount is specified to the light emission driving means when reading the original. has been done.

[Problems to be Solved by the Invention] In the above configuration, since the reference reflective surface is provided on the bottom surface of the recess, the predetermined reflectance is maintained without the reference reflective surface coming into contact with the document and getting dirty. However, instead, the position of the reference reflective surface when adjusting the amount of light emission is further away from the reading head by the depth of the recess than the position of the document surface when reading the document. For this reason, in conventional image reading apparatuses, the document is read with an amount of light emitted that is adjusted with respect to a reference reflective surface located at a position different from the document surface, resulting in a problem that reading accuracy is reduced.

[Object of the Invention] The present invention has been made in order to solve the conventional problems, and its purpose is to adjust the amount of light emitted according to the difference in distance between the reference reflective surface and the document surface from the reading head. It is an object of the present invention to provide an image reading device that can remove the influence of the above and read an image with an appropriate amount of light emitted from the surface of a document.

[Means for Solving the Problems] In order to achieve this object, the image reading device of the present invention performs reading on a reference reflective surface before starting reading a document so that the detection means obtains predetermined image information. an adjusting means for adjusting a light emitting aperture of the light emitting element so as to output; a light emitting aperture of the light emitting element adjusted so that the detection means outputs predetermined image information by reading with respect to a reference reflective surface; Based on the relationship between the amount of light emitted by the light emitting element adjusted so that the detection means outputs predetermined image information by reading a standard document supported by the cooperation of the head and the document holding member. , comprising a correction means for correcting the light emission amount adjusted with respect to the reference reflective surface before the start of reading the document, and a designation means for specifying the corrected light emission amount to the light emission drive means when reading the document. It is said that

[Function] With the above configuration, the reference reflection is performed before the document reading starts, based on the relationship between the light emission amount adjusted for the reference reflective surface and the light emission amount adjusted for the standard document, which are determined in advance. The amount of light emitted that has been adjusted for the surface is corrected, and the document is read using the corrected amount of light emitted.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings. This embodiment relates to an image reading device that reads a black and white image on a document surface.

First, the configuration of this embodiment will be explained with reference to FIGS. 1 and 2.

FIG. 2 is a cross-sectional view showing an image reading section where images are read and its surrounding area. In the figure, reference numeral 52 denotes an image reading section, and an introduction section 54 for introducing the original 50 into the image reading section 52 and an ejection section 56 for ejecting the original 50 from the image reading section 52 are provided on both sides of the image reading section.

The introduction section 54 includes a small diameter roller 62 and a large diameter roller 64. The small-diameter roller 62 is biased toward the large-diameter roller 64 by a leaf spring (not shown), and the document 5
0 is sandwiched between the rollers 62 and 64 against the biasing force of the leaf spring, and in this state, the large diameter roller 64 is rotated to feed the document 50. The discharge section 56 also includes a small diameter roller 66 and a large diameter roller 68, and the original 50 is sent in the same manner.

The reading unit 52 is provided with a reading head 70, and a light emitting diode (hereinafter referred to as LED) is installed in the reading head 70.
) 72, a light emitting side optical fiber 74, a photodiode (hereinafter referred to as PD) 76, and a light receiving side optical fiber 78. One end of the light-emitting optical fiber 74 is connected to the LED 72, while the other end is connected to the upper surface (hereinafter referred to as the reading surface) 71 which is the reading surface of the reading head 70.
The illumination light emitted from the LED 72 is transmitted through the light-emitting optical fiber 74 and irradiated onto the document surface. The receiving side optical fiber 78 has one end connected to the PD7.
6, while the other end is exposed to the reading surface 71, and the reflected light from the document surface is transmitted to the light-receiving optical fiber 78.
and transmitted to the PD 76.

A document holding member 80 is provided above the reading head 70 . The original holding member 80 is supported by a support base 86 so as to be able to approach and separate from the reading head 70, and is urged by a spring 88 in a direction toward the reading head 70. Furthermore, a recess 82 that opens downward is formed on the surface of the document holding member 80 that faces the reading surface 71, and the bottom surface of the recess 82 forms a white reference reflective surface 84 having a predetermined reflectance. and is used to adjust the amount of light emitted by the LED'72, which will be described later.

With this configuration, when the light emission amount is adjusted with respect to the reference reflective surface, the original holding member 80 is positioned as shown by the solid line in the figure, and when the original is read, the original 50 is placed at the position shown by the imaginary line. As a result, the document holding member 80 is retracted to the position shown by the imaginary line, and the reading head 70 is
The document 50 is supported in cooperation with the document 50.

FIG. 1 is a block diagram showing the electrical configuration.

The CPU 10 constitutes a control means with a ROM 12, a RAM 14, and an electrically erasable/writable nonvolatile E2 FROM 16. The CPU 10 outputs light amount data to a D/A converter 20, which is a light emission driving means Input of image information from the comparator 22h) serving as a detection means and E
Writes and reads data to and from 2PROMI6. The D/A converter 20 converts the output from the CPU 10 into a corresponding analog signal, and the LED 72 is driven by this analog signal and emits light with an amount of light corresponding to the light amount data to illuminate the surface of the document. The PD 76 receives the reflected light from the document surface and outputs a signal according to the amount of received light, and the comparator 22 compares this output signal with a reference value and determines the brightness and darkness of the reflected light, that is, the white and black of the document surface, respectively. 1.0 of 2
This binary signal is made to correspond to the value signal and is converted into CP as image information.
Send it to Lllo.

Next, the operation of the CPU 10 in this embodiment will be explained with reference to the flowcharts shown in FIGS. 3(a) to 3(C). In this embodiment, the amount of light emitted is adjusted in advance for a standard white document, which has a reflectance almost the same as the background color of paper normally used as a document, and the reference reflective surface 84. E
2PROM 16, and before the start of document reading, adjust the light emission amount again with respect to the reference reflective surface 84, and then read the document by multiplying the appropriate light emission amount by the correction coefficient read from the E2PROM 16. This is the amount of light emitted at the time.

FIG. 3(a) is a flowchart showing the operation of adjusting the amount of light emitted. When the CPU 10 operates according to the flowchart shown in FIG. 3(d), it constitutes an adjusting means.The CPU 10: In step (hereinafter referred to as S) 11, the reference value of the comparator 22 is set to a value for adjusting the light emission amount that is slightly higher than that during document reading, and in 312, the light amount data is set to the minimum value. The light amount data is output to the D/A converter 20, and the LED 72 emits light according to the light amount data corresponding to the light amount data.The comparator 22 compares the output signal of the PD 76 with the reference value and outputs a binary signal of O or 1. Output and CPU10
If the output of the comparator 22 is O at 314, then S
In step 15, the light amount data is increased and the process returns to step 313. Thereafter, steps 313 to 315 are repeated to gradually increase the light amount data from the minimum value, and the light amount data when the output of the comparator 22 changes from 0 to 1 is set as the appropriate light amount data, and the adjustment of the light amount is completed. . By performing this adjustment on the reference reflective surface 84 or the standard white original,
Regardless of optical system characteristics and manufacturing errors, the reference reflective surface 84
Alternatively, the reflectance of a standard white document becomes a threshold value for black and white discrimination with respect to the reference value for adjusting the amount of light emitted. Note that when reading a document, the reference value of the comparator 22 is set to a value lower than that for adjusting the amount of light emitted, so the threshold value for black and white discrimination when reading a document is a value lower than the reflectance.

FIG. 3(b) is a flowchart showing the operation of creating correction coefficients. When the CPU 10 operates according to the flowchart shown in FIG. 3(b), it constitutes a correction means. At 321, the CPU 10 adjusts the amount of light emitted by the reference reflecting surface 84 as described above, and obtains appropriate light amount data D1.
seek.

At step 322, the CPU 10 places the standard white original on the reading section 52, and similarly adjusts the amount of light emitted from the standard white original to obtain appropriate light amount data D2. CPU10
calculates the correction coefficient K (K=D2/D1) at 323,
In S24, this correction coefficient K is stored in the E2 PROMI 6, and the creation of the correction coefficient is completed. This correction number represents the relationship between the appropriate light amount for the reference reflective surface 84 and the appropriate light amount for the standard white original, and is related to the difference in position and reflectance between the reference reflective surface 84 and the standard white original. are doing. Note that the appropriate light amount data D1. Since D2 is obtained at approximately the same point in time, there is no influence between them due to changes in the characteristics of the optical system, and the correction coefficient always has a substantially constant value.

FIG. 3(C) is a flowchart showing the operation before the start of document reading. When the CPU 10 operates according to the flowchart shown in FIG. 3(C), it constitutes a specifying means. In step 331, the CPU 10 adjusts the amount of light emitted from the reference reflecting surface 84 to obtain appropriate light amount data D3. C.P.
U10 reads the correction coefficient K from the E2PROM 16 in S32.

In S33, the CPU 10 multiplies the appropriate light amount data D3 by the correction coefficient K to calculate reading light amount data D4 (D4=D3*K). The CPU 10 outputs the reading light amount data D4 to the D/A converter 20 in S34, and thereafter reads the original.

Suppose that the appropriate light amount data D5 is obtained by adjusting the light emission amount for a standard white document before the document reading starts, and as described above, the appropriate light amount data D5 for the standard white document obtained at the same time and the appropriate light amount data D5 are obtained. Since the ratio of the appropriate light amount data to the reference reflective surface is approximately constant, D5/D3=
If D2/D1 (=K) holds, then D5=D3*
= D4. Therefore, as described above, by setting the reading light amount to be the amount of light emitted by multiplying the amount of light emitted by the correction coefficient by the amount of light emitted that was adjusted with respect to the reference reflective surface before starting to read the original, the amount of light emitted for a standard white original before starting to read the original can be calculated. In the same way as adjusting the amount of light emitted from the document surface, an image can be read with an appropriate amount of light emitted from the document surface.

In the above embodiment, the correction coefficient is the appropriate ratio of the light emission amount obtained by adjusting the light emission amount in advance for the standard white original and the reference reflective surface. The light emission amount is adjusted again with respect to the reference reflective surface and the corrected light emission amount is multiplied by the correction coefficient, but these are the light emission amount adjusted with respect to the reference reflective surface and This is only an example of the relationship between the amount of light emitted and the amount of light emitted adjusted for a standard white original, and a method for correcting the amount of light emitted that is adjusted for the reference reflective surface before the start of document reading, and is limited only to these. isn't it.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, the light emission amount adjusted for a reference reflective surface determined in advance and the light emission amount adjusted for a standard document can be adjusted. Based on the relationship between The effect of the difference in distance from the reading head to the document surface on the old light emitting section is eliminated, and images can be read with an appropriate amount of light emitted from the document surface.

[Brief explanation of the drawing]

1 to 3 relate to an embodiment embodying the present invention, in which FIG. 1 is a block diagram, FIG. 2 is a sectional view around the image reading section, and FIG. 3 is a flow chart. In the figure, 10 is a CPU, 12 is a ROM, 14 is a RAM, 1
6 is an E'' PROM, 20 is a D/A converter, 22 is a comparator, 70 is a reading head, 72 is a light emitting diode, 76 is a photodiode, 80 is a document holding member,
82 is a recessed portion, 84 is a reference reflecting surface, and 88 is a spring. Figure 3(a)

Claims (1)

[Scope of Claims] 1. A reading head having a light emitting element that emits illumination light for illuminating the document surface and a light receiving element that receives reflected light from the document surface and generates a signal according to the amount of light received; It is arranged so that it can approach and separate from the reading head, is biased toward the reading head, contacts the document from the side opposite to the reading head, cooperates with the reading head, supports the document, and supports the reading head. A document holding member having a recess formed on opposing surfaces and a reference reflective surface having a predetermined reflectance on the bottom of the recess, and a document holding member that detects a signal corresponding to the amount of light received by a light receiving element and converts it into image information. In an image reading device comprising: a detection means; and a light emitting driving means for causing a light emitting element to emit light at a specified amount of light emission, before starting reading a document, reading is performed on a reference reflective surface so that the detection means is set to a predetermined level. adjusting means for adjusting the amount of light emitted by the light emitting element so as to output image information; and adjusting means for adjusting the amount of light emitted from the light emitting element so that the detection means outputs predetermined image information by reading with respect to a reference reflective surface. and the light emission amount of the light emitting element adjusted so that the detection means outputs predetermined image information by reading a standard document supported by the cooperation of the reading head and the document holding member. a correction means for correcting the light emission amount adjusted with respect to the reference reflective surface before the start of reading the document based on the relationship; and a designation means for specifying the corrected light emission amount to the light emission driving means when reading the document. An image reading device comprising: 2. In the image reading device described in claim 1, the control means for performing data processing and various controls for image reading reads the reference reflective surface, and the detection means detects a predetermined value. a first adjusting means for adjusting the amount of light emitted from the light emitting element so as to output image information; and a first adjusting means for adjusting the amount of light emitted from the light emitting element so as to output image information; a second adjusting means for adjusting the amount of light emitted by the light emitting element so as to output image information of the light emitting element; and a second adjusting means for adjusting the amount of light emitted from the light emitting element so as to output image information of the light emitting element; An image reading device comprising: means for determining the relationship;