JPH04189060A - Picture reader - Google Patents

Abstract

PURPOSE:To detect deficiency of luminous quantity accurately by raising a luminous quantity deficient alarm signal when a range coincidence signal is consecutive for a prescribed picture element number. CONSTITUTION:An 8-bit digital comparator 10 compares a luminous quantity signal 24 with an upper limit and a lower limit stored in 8-bit digital memories 8, 9 and when the luminous quantity signal 24 is within a range between the upper limit and the lower limit, a range coincidence signal 21 is outputted. When the range coincidence signal 21 is outputted, a 2-input logic circuit 11 stops an output of a counter reset signal 26 to a 3-bit digital counter 12, then the counter 12 counts consecutive picture element number in the range coincidence signal 21. When a count is going to be 8 from 7, a carry is caused on the counter 12, a luminous quantity deficiency alarm signal 22 is generated to detect the deficiency of luminous quantity.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an image reading device used for reading images such as an image scanner or a facsimile machine, in which the white color of a document and the paper feed device, etc. The present invention relates to an image reading device that identifies a document portion by distinguishing between black and black without using a document size sensor.

[Prior Art] A conventional image reading device that distinguishes between the white color of a document and the black color other than the image of the document, such as a paper feeder, and identifies the document portion without using a document size sensor, includes, for example, the following: There is an image reading device described in Japanese Unexamined Patent Publication No. 6.4-78073.

The image reading device described in Japanese Patent Application Laid-Open No. 64-78073 is
- Providing means for identifying the width of the document based on the white color of the document detected by the dimensional image sensor and the black color other than the image of the document such as the paper feeder, without using a document size sensor;
This makes it possible to identify the manuscript portion.

On the other hand, an image reading device for boat fishing reads an image by measuring the amount of reflected light using a light source such as an LED array, but if the light source has an insufficient amount of light, accurate image reading cannot be performed. As a countermeasure against this problem, many image reading apparatuses are equipped with means for detecting insufficient light quantity and notifying the operator of the abnormality. Several light intensity detection means have been invented to detect insufficient light intensity.
The image reading device disclosed in Japanese Patent No. 64 detects a light amount abnormality if even one pixel has a portion where the light amount is outside the appropriate range, and notifies the operator of the abnormality to prompt the operator to replace the light source.

[Problems to be Solved by the Invention] However, the conventional light insufficient detection device is compatible with an image reading device that identifies the document portion by distinguishing between the white color of the document and the black color other than the image of the document such as a paper feeder. Therefore, it is not possible to detect insufficient light intensity while scanning the document.

For example, malfunctions may occur, such as detecting a black part other than the original image, that is, a background member, as an abnormality in the amount of light, or detecting fine foreign matter such as paper dust attached to a background member as an abnormality in the amount of light. be.

Therefore, the present invention distinguishes between fine foreign matter such as paper dust attached to the back member and the blank area of the document, and accurately detects the blank area of the document to prevent insufficient light for the document, and even to detect the LED array. It is an object of the present invention to provide an image reading device that can detect a partial shortage of light amount due to a defect in one element of a collective light source.

Means for Solving Problems R The present invention comprises an image reading means for detecting the amount of light reflected from a document, a back member disposed on the opposite side of the document from the image reading means, and a back member for the image reading means. In an image reading device equipped with a light quantity insufficient detection means for detecting a light quantity deficiency based on a light quantity signal, the back member has a width equal to or larger than the main scanning direction reading width of the image reading means and has a dark surface such as black or dark gray. The detection range of the image reading means is the back surface member and the document, and the light amount insufficient detection means has a value that is approximately equal to the amount of light reflected from the back surface member, with the upper limit value being a limit value that allows insufficient light amount of the image reading means. limit value storage means for storing the lower limit value; and range match signal output means for detecting that the light amount signal from the image reading means is between the upper limit value and the lower limit value of the limit value storage means and outputting a range match signal. , and an insufficient light quantity warning signal output means for outputting an insufficient light quantity warning signal when the range matching signal continues for a predetermined number of pixels.

[Operation] The range match signal output means detects whether the light amount signal from the image reading means is within the range between the lower limit value and the upper limit value stored in the limit value storage means, and if it is within the range, the range match signal is detected. Output a signal. The upper limit value is a value for reducing the amount of light if it is less than this value, and the lower limit value is a value for removing the background member from the decrease in the amount of light. The range match signal indicates an insufficient amount of light, but if there are fine foreign objects such as paper dust attached to the background member, the amount of light reflected from these fine foreign objects is usually small, so the range match signal is output. Therefore, in order to prevent erroneous detection due to fine foreign objects, the present invention further includes a light quantity insufficient warning signal output means. The insufficient light quantity warning signal output means outputs an insufficient light quantity warning signal when the continuous output of the range matching signal exceeds a predetermined value approximately equal to the size of paper powder, and detects a true decrease in light quantity, not paper powder. .

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a flowchart of one embodiment of the invention. Each step of this flowchart will be explained.

Step (1): At the start of detection, a determination counter for paper dust detection prevention that counts how many pixels of continuous range matching signals have been output is reset to initialize the count value to zero.

Step (2): Compare whether the light amount signal is within the range of the upper limit value and lower limit value, and if it is within the range, increment the value of the judgment counter by 1 at the edge of the pixel clock synchronized with document reading, and make it within the range. If not, the determination counter is reset to count the number of pixels for which range match signals are continuously output.

Step (3): If the count value of the determination counter is equal to the predetermined value, an insufficient light amount warning signal is output, and the detection operation is terminated as a decrease in light amount.

Step: Knob (4) If the count value of the second determination counter has not reached the predetermined value, it is determined whether the detection has been completed, and if the detection has not been completed, the process returns to step (2) to continue the detection operation. If the detection is completed, the light source is considered normal and the detection operation is terminated.

FIG. 1 shows an embodiment of this flowchart.

1 is a manuscript. 2 is a platen roller whose surface is black or dark gray, and is a back member. The color of the back member is not particularly limited to black or dark gray, and may be any color as long as it is dark enough not to be mistaken for a decrease in the amount of light. Furthermore, the structure of the back member does not need to be a platen roller; in short, it can be of any dark color that can be clearly distinguished from the original when scanned by the image reading means 3 and that will not be mistaken for a decrease in light intensity. good. For example, in the case of the document table moving method, a plate-shaped document cover may be used.

4 is a document illumination light source that illuminates the document 1; 5 is an optical lens;
6 is a one-dimensional image sensor, and 7 is an 8-pixel AD converter, which constitutes image reading means 3 that scans the original and the back member and outputs a light amount signal 24.

Note that the length of the platen roller 2 is greater than the main scanning width of the one-dimensional image sensor 32. The image reading means 3 is not limited to this configuration; the main scanning width is equal to or larger than the document and is longer than the length of the platen roller 2;
Any configuration may be used as long as the light amount signal is output as a value rather than as black or white.

8 is an 8-bit digital memory for storing an upper limit value, and 9 is an 8-bit digital memory for storing a lower limit value, which is limit value storage means. The limit value storage means is not limited to an 8-bit digital memory, but may have a different number of bits as necessary, or may have any configuration as long as it can store digital values of the required number of bits. It may also be configured with a knob switch or the like. Further, as long as the light quantity insufficient detection means is constructed of an analog system, the limit value storage means may have any construction as long as it stores analog values.

10 is an 8-bit digital comparator. Also, the light amount signal is compared with the value stored in the limit value storage means, and the light amount signal is recorded as the limit value.

Any configuration may be used as long as it determines whether the two values stored in the storage means are within the range and outputs the result. The 2-manual logic circuit 11 and the 3-bit digital counter 12 constitute insufficient light quantity warning signal output means. This insufficient light quantity warning signal output means can also reset its output as appropriate, and outputs an insufficient light quantity warning signal when the number of pixels for which range match signals are continuously output reaches a predetermined value indicating the size of paper powder. Any configuration may be used as long as it has such a configuration.

Immediately before the image reading means 3 reads from the leading edge of the original and starts main scanning of a portion approximately 2.5 mm from the leading edge of the original, a control unit (not shown) sends a counter initialization signal 25 to the two-man logic circuit 11. The count value of the 3-bit digital counter 12 is reset. This value of 2.5 mm may be changed as appropriate.

When the image reading means 3 starts main scanning of a portion approximately 2.5 mm from the leading edge of the document, the 8-bit digital comparator 10
compares the light amount signal 24 with the upper and lower limit values stored in the 8-bit digital memory 8.9, and calculates the light amount signal 24.
If it is within the range of the upper limit and lower limit, the range match signal 21 is output, and if it is not within the range, the range match signal 21 is not output.

When the range match signal 21 is output, the two-man logic circuit 11
stops outputting the counter reset signal 26 to the 3-bit digital counter 12. If the range match signal 21 is not output, the two-man logic circuit 11 outputs a counter reset signal 26 to the 3-bit digital counter 12.

When the counter reset signal 26 is output, the count value of the 3-bit digital counter 12 becomes 0, so the pixel clock signal 27 is not counted. However, when the output of the counter reset signal 26 stops, the 3-bit digital counter 12 stops reading. Pixel clock signal 27 output in synchronization
, and the number of consecutive pixels of the range matching signal 21 is counted. If the output of the range match signal 21 stops before the count value reaches 8, the count value of the 3-bit digital counter 12 is reset to 0, and when the range match signal 21 is output, it starts counting again from the beginning.

Furthermore, when the count value is about to increase from 7 to 8, the 3-bit digital counter 12 overflows and enters a carry state, generating an insufficient light quantity warning signal 22 and detecting a decrease in the light quantity. That is, if there is paper dust within the range of the upper and lower limits of the amount of reflected light, the range match signal 21 is output, but since the size of the paper dust is less than 8 pixels, the insufficient light amount warning signal 22 is output. Not done. However, in the case of a true decrease in light quantity, the range matching signal 21 is output for eight or more pixels in succession, so the light quantity insufficient warning signal 22 is output, the insufficient light quantity is detected, and the detection operation ends.

This is repeated for one main scanning line, and if the insufficient light quantity warning signal 22 is not output during that time, it means that no decrease in the quantity of light has been detected.

Note that although this light intensity detection is performed once each time one side of the original is read, it may be performed multiple times, or it may be performed every time several sides of the original are read.

In the above embodiments, a case has been described in which the insufficient amount of light is detected using the image reading signal, but reading the image and detecting the insufficient amount of light may be performed separately.

[Effects of the Invention] In the present invention, since the light intensity detection means has a characteristic configuration of a range matching signal output means and a light intensity insufficient warning signal output means, false detection due to the back member or paper dust attached to the back member can be avoided. It is possible to accurately detect an insufficient amount of light for a document without causing a problem. Furthermore, it is possible to accurately detect a partial light quantity shortage due to an abnormality in one light emitting element that occurs when a light source such as an LED array is used.

In addition, since the light amount signal of the original is used, insufficient light amount can be detected in any blank area on the original.

Furthermore, since the insufficient light quantity warning signal is output even when the background color of the document is dark, the insufficient light quantity warning signal can also be used to detect a document that is not suitable for reading.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a flowchart of one embodiment of the present invention. 1. Original document, 2. Roller (back member), 3. Image reading means, 4. Original illumination light source, 5. Optical lens, 6. One-dimensional image sensor, 7. 8-bit AD converter, 8. 8-bit digital memory. (limit value storage means), 9, 8-bit digital memory (limit value storage means), 10, 8-bit digital comparator (range-match signal output means), 1142 manual logic circuit, 12, 3-bit digital counter (2 manual logic circuit and means for outputting a light intensity signal). Patent applicant Fuji Xerox Co., Ltd.

Claims (1)

[Scope of Claims] An image reading means for detecting the amount of reflected light from a document; a back member disposed on the opposite side of the document from the image reading means;
In an image reading device equipped with a light amount insufficient detection means for detecting an insufficient amount of light based on a light amount signal of the image reading means, the back member has a width equal to or larger than the reading width in the main scanning direction of the image reading means, and has a black or black surface. It is a dark color such as dark gray,
The detection range of the image reading means is the back surface member and the document, and the light amount insufficient detection means stores a limit value that allows insufficient light amount of the image reading means as an upper limit value, and a value that is approximately equal to the amount of light reflected from the back surface member as a lower limit value. a limit value storage means for detecting that the light amount signal from the image reading means is between the upper limit value and the lower limit value of the limit value storage means, and a range match signal output means for outputting a range match signal; An image reading device comprising: an insufficient light quantity warning signal output means for outputting an insufficient light quantity warning signal when the signal continues for a predetermined number of pixels.