JPS6156573A - Detector for deterioration of light source of picture reader - Google Patents

Abstract

PURPOSE:To attain proper and automatic detection for deterioration of each light source regardless of the variance of each light source, the number of light sources and the arrangement of light sources, etc., by obtaining the mean luminance level among divided minor areas, storing said mean level in an initialization mode of the light source and obtaining the difference between the stored mean level and the present mean level to recognize the deterioration of the light source. CONSTITUTION:The first mean value is calculated when the use of light sources 11, 12&v is started (initial and exchange time points). The luminance mean value of each pat is divided into minor areas and stored in an initial value memory 5. The second mean value is calculated in a check mode (e.g., when the power supply is made every morning). In this case, the output of a mean value calculating circuit 4 is supplied to a present value memory 6. Then a differential circuit 7 obtains the difference between the mean luminance levels of the same minor areas of both memories 5 and 6. This difference is compared with the reference value (ref) through a comparator 8. This value (ref) is equal to a level that shows the allowance limit of deterioration of the light source. Then the deterioration output OUT is delivered when the output of the circuit 7 exceeds the value ref.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light source deterioration detection device for an image reading device including a plurality of light sources.

[Conventional technology]

In an image reading device that uses a photoelectric conversion element such as a COD (charge-coupled device) in a scanner section, it is preferable to maintain a constant brightness level of a light source that illuminates the surface of a document. However, as the light source deteriorates over time, it is difficult to maintain a constant illuminance on the document surface, and if the fixed slice method is used to distinguish between black and white even when the illuminance changes, there will be an increasing number of cases in which white is mistaken as black or vice versa. , the resolution etc. gradually decrease. For this reason, conventionally, the light source has been replaced periodically.

[Problem that the invention seeks to solve]

However, with this method, individual variations in the light sources, number of light sources,
It is difficult to appropriately deal with cases where the arrangement etc. are different, and it is difficult to obtain a constant brightness level until the light source is replaced with a new light source. The present invention memorizes the brightness level of each part of the document surface when the light source is first used, compares that value with the current brightness level, detects when the difference exceeds a certain value, and automatically This is an attempt to issue instructions for replacing the light source.

[Means for solving problems]

The present invention provides a light source deterioration detection device for an image reading device that illuminates a reading area with a plurality of light sources, receives light from the area with a scanner unit, and optically reads an image in the area. a circuit that divides into a plurality of small areas and calculates an average value of the brightness level of each small area read by the scanner unit;
゛An initial value memory stores the output of the average value calculation circuit obtained by setting a non-image original in the reading area at the initial stage of use of the light source, and stores the same non-image original at the time of inspection. a current value memory that stores the output of the average value calculation circuit obtained by setting the original in the reading area, dividing it into each small area;
A difference circuit that calculates the difference in average luminance level of the same small area of both memories, and a detection circuit that compares the output of the difference circuit with a reference value and detects a small area that outputs a difference exceeding the reference value. It is characterized by:

[Effect]

Generally, the brightness level is not uniform over the entire reading area depending on the type, number, arrangement, etc. of the light sources used, but the level within the small areas that are divided into several areas is almost uniform. Therefore, in the present invention, the average value of the brightness level in each small area is taken, the average value at the initial stage of the light source is stored in memory, and the difference between this and the current average value is determined to recognize the deterioration of the light source. .

In this way, since the comparison is made for each small area, locally bad parts can be easily detected, and it is also possible to determine and indicate which of the plurality of light sources has deteriorated. This will be explained in detail below with reference to illustrated embodiments.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. 11.
12,13. . . . is a plurality of light sources.

In this example, the original 10 placed 92 on the transparent reading stand 2 is irradiated from below with these lights, and the transmitted light is received by the scanner unit 3. The scanner section 3 consists of an information input camera equipped with a line sensor such as a COD, and a circuit that converts analog image information output from the camera into, for example, an 8-bit digital value and then binarizes it. Figure 2 shows this C.
FIG. 2 is an explanatory diagram of an OD scanner. The COD scanner 31 arranges, for example, 1 (L!4) bits of COD in a line, and scans the document surface electrically in the X direction and mechanically in the Y direction.The base 10A of the document 10 is white. So, if a black image 10B is drawn there, the transmitted light in the base 10A part is strong (and the transmitted light in the image 10B part is weak, corresponding to the partial strength of this transmitted light. A large amount or small amount of charge and a high and low voltage are generated in each element of the COD scanner 31. Since this voltage value is an analog value, it is converted into digital data (image data) of, for example, 8 bits per pixel. The image data is sent to an image processing system such as an image memory on the one hand, and is input to the area average value calculation circuit 4 on the other hand.

Note that FIG. 1 shows only the device configuration related to light source deterioration detection.

For detection of light source deterioration, a document 10 having only a base 10A without an image 10B (hereinafter referred to as a non-image document) is used. and,
When the entire area of the non-image original 10 is taken as a reading area by the scanner 31, the entire area is divided into a plurality of small areas in a matrix, and the average brightness level of each of the small areas is determined. FIG. 3 is an explanatory diagram of this. This figure shows the brightness levels obtained from a non-image original in two axes, with 2 floors per pixel G, and the bottom is black (digital values are all 0).
), the highest level is white and the digital value is all F), even if you scan a non-image original with uniform density, the reading area A
The brightness level is not uniform over the entire area (for example, it is low at the periphery). Therefore, this reading area A is formed into a plurality of small areas A + + A 2 in a matrix.

Classify into... In this way, the brightness level within each small area becomes approximately average, so the average value is calculated by the area average value calculating circuit 4 of FIG. 1 and is used to represent the brightness level of the small area.

The first average value calculation is performed for the light sources 11, 12. ...... at the beginning of use (initial and replacement). The average brightness value of each part is divided into each small area and stored in the initial value memory 5. Since the output of the scanner unit 3 corresponds to horizontal scanning lines on a television, the average brightness value of each small area is calculated using the number of horizontal (horizontal) sections of the document surface as n, the number of vertical sections as m, and the section. (Small area) Inner water rate Assuming the number of scanning lines as β, divide the output (1 horizontal scanning line) into n, calculate the sum of each part, and repeat this twice to obtain the two totals for each phase. (Since each small area has the same size, division for calculating the average value can be omitted). The above process is repeated m times for the entire document surface. The initial value memory is a non-volatile memory such as a floppy disk. The next average value calculation is performed at the time of inspection (for example, every morning when the power is turned on). The output of the average value calculation circuit 4 at this time is stored in the current value memory 6.

This memory only needs to be rewritable (non-volatility is not required). This is done by dividing each small area.Then, the difference circuit 7 uses the average brightness level of the same small area in both memories 5.6. The comparison circuit 8 calculates the difference between the reference values r
Compare with ef.

This reference value ref is a value indicating the allowable limit of deterioration of the light source, and when the output of the differential circuit 7 exceeds this value, the deterioration output O
Since this output OUT is obtained for each small area, the brightness level of each part of the document surface is displayed individually.For example, if the light source 12 in FIG. 1 has deteriorated significantly, Since degraded output OUT occurs in one or more small areas in the vicinity, it is understood that only the light source 12 needs to be replaced. It is conceivable to perform the above-mentioned processing in units of pixels G instead of in units of small areas, but if you do this, the memories 5 and 6 will have a large capacity (for example, if area A is
If it is decomposed into 1024 dots, it becomes 1 MB (8 bits per dot), which is not practical. Moreover, even if this method is adopted, there is not much difference from the small area averaging method. It is preferable to link the output OUT of the comparator circuit 8 with the read address of the memory 5.6, and to turn on a deterioration warning lamp corresponding to each light source.

〔Effect of the invention〕

As described above, according to the present invention, in a document reading device using a plurality of light sources, there is an advantage that deterioration of each light source can be appropriately and automatically detected regardless of variations, number, arrangement, etc. of each light source. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of a CCD scanner, and FIG. 3 is an explanatory diagram of brightness level and average value calculation. In the figure, 3 is a scanner section, 4 is an area average value calculation circuit, and 5 is a scanner unit.
is initial value memory, 6 is current value memory, 7 is differential circuit, 8
10 is a comparison circuit, 10 is an original, 11° 12, . . . is a light source, 31 is a CCD scanner, A is a reading area, A1. A
2. . . . is a small area.

Claims (1)

[Claims] In a light source deterioration detection device for an image reading device that illuminates a reading area with a plurality of light sources and optically reads an image within the area by receiving light from the area with a scanner unit, the reading area is divided into a plurality of small areas. a circuit that calculates the average value of the brightness level of each small area read by the scanner section, and a circuit that calculates the average value obtained by setting a non-image original in the reading area at the initial use of the light source. The output of the average value calculation circuit obtained by setting the same non-image original in the reading area at the time of inspection is divided into each small area. A current value memory that stores the current value, a difference circuit that calculates the difference in the average brightness level of the same small area in both memories, and a small area that compares the output of the difference circuit with a reference value and outputs a difference that exceeds the reference value. What is claimed is: 1. A light source deterioration detection device for an image reading device, comprising: a detection circuit for detecting.