JPS6023391B2 - Graphic input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphic input device that prevents photoelectrically converted graphic information from becoming inaccurate due to variations in the Koryu conversion element, lens, illumination means, etc. .

There have been many graphic input devices that scan and photoelectrically convert information such as graphics and characters written on a manuscript, but recently, due to variations in photoelectric conversion elements, lenses, lighting means, etc.
A method is being considered that prevents photoelectrically converted graphic information from becoming inaccurate.

The graphic input device will be explained with reference to FIG. As shown in FIG. 1, the document 1 to be input is transferred to the
The original is sent in the direction of arrow 8 by a document transport means consisting of feed loafs 4, 5 and pinch rollers 6, 7. Further, the original 1 is illuminated by the illumination means 9 in a line perpendicular to the direction of movement thereof, and a single beam of reflected light from the original 1 is focused onto the light receiving element array 12 by the lens 11. The light-receiving element array 12 has a large number of light-receiving elements arranged in a row in a direction perpendicular to the direction in which the original 1 is fed. therefore,
By sequentially scanning the output of each light-receiving element, the original 1 can be scanned and photoelectrically converted in a direction perpendicular to its feeding direction.Furthermore, by this and the scanning by transporting the original 1, Original 1 is raster scanned. The output 13 of the light receiving element array 12 is amplified by an amplifier 14 and then introduced into an A/D converter 15 and a quantization circuit 16. Note that the output of the quantization circuit 16 is used as graphic information. By the way, the lighting means 9,
Due to the non-uniformity of the lens 11, the light-receiving element array 12, etc., the level of the obtained photoelectric conversion output 13 varies in the direction of scanning by the light-receiving element array 12 even when the original 1 is completely white.

FIG. 2 shows output level fluctuations, where the horizontal axis shows the element number of the light receiving element array 12 having n light receiving elements, and the vertical axis shows the output level. Here, the output level is
It is written so that when it is white, it is upward, and when it is black, it is downward. If the document 1 on which a figure is written is taken with such fluctuations in the output level, the density and thickness of the line of the figure will not be accurately photoelectrically converted. Further, if the output level fluctuates greatly, the white background portion of the document 1 may become black and the black line portion may become white. Therefore, the actual document is read while measuring the fluctuations in the output level and correcting the fluctuations in the output level based on the measurement results.

That is, first, in order to measure the fluctuations in the output level, a white original (which is constant at any position and has the highest reflectance of the actual original used; hereinafter referred to as the standard original) was inserted as original 1. , then the light receiving element array 1
The output 13 of 2 is amplified by an amplifier 14. In this case, the amplifier 14 is connected to the constant generating circuit 19 by connecting the movable contact 183 of the switch 18 to the first fixed point 18.
The amplification factor is kept constant by the constant. Therefore, the output of the amplifier 14 has an output fluctuation as shown in FIG. It is stored in the memory 17 as a D-converted digital value. After doing this, the document 1 is made into an actual document and is read. In this case, the movable contact 18 of the switch 18
By connecting to the second fixed contact 182 of No. 3, the amplification factor of the amplifier 14 is switched by the output of the memory 17 corresponding to each element of the light receiving element array 12, thereby correcting fluctuations in the output level. That is, as an example, if the output level of a certain element at the time of measurement is x and the amplification factor of the amplifier 14 is 1, the value x is written in the memory 17, but when reading an actual document, , store the value x in memory 7
The amplification factor of the amplifier 14 is set to c/x. As a result, if the reflectance of the document is equal to the reflectance of the standard document at the time of measurement, the output of the amplifier 14 becomes X=C, and is normalized to C. Then, if the same operation is performed for all the elements of the light-receiving element array 12, the output of the amplifier 14 corresponding to each light-receiving element in the case of a document equivalent to a standard document will all be standardized to C. In this way, fluctuations in the output level can be corrected and accurate graphic information can be input. The above is a graphic input device that corrects output level fluctuations and inputs accurate graphic information, but the standard manuscript used in this device is
It is necessary to have a constant reflectance over the entire field of view of the light-receiving element array 12 on the document surface, and to have a reflectance equivalent to the maximum reflectance of the white background portion of the document inputted by the parenthesis device.
Therefore, this standard manuscript requires the use of special paper with minimal reflectance unevenness, special care in handling to prevent dirt from adhering to it, and it must be discarded after one or a few uses. Ta. Therefore, in order to simplify the handling of the device and the standard original, the upper edge of the original to be taken is left blank, and that area is used as the light-receiving element array 1.
2 is performing scanning photoelectric conversion, the movable contact 183 of the switch 18 is connected to the first fixed contact 18,
It is conceivable to connect the device to a device to perform measurement operations.

However, it is impossible to accurately correct the blank area at the top of the original, which should be taken lightly, compared to a standard original due to the size of the reflectance and the location, but it is not a problem in practice. Even for originals using paper with particularly low reflectance in the white area, the white background level is corrected to raise it to the maximum level set by the device, so the signal output increases, and the following slice level measurement circuit (not shown) ), the quantization circuit 16, etc. have a large S/N ratio,
This can be made easier in terms of quantization resolution, etc. As described above, the graphic input device which performs variation correction using the blank area at the top of the original as a standard has one advantage: 1. There is no need to prepare a standard white original.

2. A photoelectric conversion element that can be corrected for each document to be read, so that it fluctuates at intervals longer than the intervals at which documents are inserted into the device;
It is possible to exert a correction effect on variations in lenses, lighting means, etc. (mainly caused by environmental conditions such as temperature and humidity, changes over time, etc.).

3. No special operations are required to measure correction values.

There are disadvantages such as: 1. If there is dirt in the blank area at the top of the document to be read or if there are large or medium fluctuations in reflectance, the correction will be inaccurate.

2. There must be a blank space at the top of the document to be read.

etc. The present invention has been made to eliminate the above-mentioned drawbacks, and will be described in detail below.

FIG. 3 is a block diagram showing an embodiment of the graphic input device according to the present invention, particularly the variation correction portion.

The photoelectric conversion output 13 of the light receiving element array 12 is amplified by an amplifier 14, and the output is input to an A/D converter 15.

The output of the A/D converter 15 is connected to the fixed contact 20 of the switch 20.
−, is connected to. Movable contact 20 of switch 20
2 is connected to the memory 17, and the switch 20 is connected to the fixed contact 2.
When switched to the 0-, side, memory 7 is A/D.
The output value of the converter 15 can be stored. memory 1
The output of 7 is passed through a switch 18 to change the amplification factor of the amplifier 14 to correct fluctuations in the output level. The output of the amplifier 14 is also input to a deviation detection circuit 21, which detects the variation in the output corrected based on the contents of the memory 7, that is, the accuracy of the correction. For example, the difference between the maximum value of the level in the white direction and the maximum value of the level in the black direction, that is, the maximum value of the corrected output dispersion, is detected, and it is outputted whether or not the value is larger than a specified value. The output of the deviation detection circuit 21 is input to the control circuit 22. The other fixed contact 20 of the switch 20
3, initial data for the memory 17 is output from the control circuit 22. The switch 18 and the constant generation circuit 19 are the first
This is the same as in the explanation of the figure. The operation of the circuit shown in the block diagram of FIG. 3 will be explained.

First, when the device is put into operation, the switch 20 switches the movable contact 20-2 to the fixed contact 20-3, and initial data is written into the memory 7 by the control circuit 22.

The initial data may be the same data for all words in the memory 17, or the measured value obtained by inserting a semi-white original into the device at the time the device was manufactured. A method is used in which universal variation correction data (for example, the average value of the decrease in photoelectric conversion output that occurs at both ends of the field of view due to optical systems such as lamps and lenses) is written for all devices of the same model. memory 1
When writing of data to 7 is completed, switch 20
is switched to the other fixed contact side. The next document to be read is inserted into this device, and the paper feeding mechanism brings the blank area at the top of the document into the field of view of the photodetector array. At this time, the contents of the memory 7 are read out in synchronization with the operation of the photodetector array, and the amplifier 14 amplifiers are changed to perform variation correction.

A corrected image signal is obtained at the output of the amplifier 14, and the deviation detection circuit 21 detects the deviation of the image signal, and the control circuit 2 detects whether the deviation value is larger than a certain specified value.
Output to 2. In the first case, if it is less than the specified value, it is assumed that the blank area of the inserted original is not soiled and has a constant reflectance, and when the next photodetector array scans, the switch is 18 is switched to the constant generating circuit 19 side, the amplification factor of the amplifier 14 is kept constant, and the A/D converted value of its output is written into the memory 7. When the writing is completed, the switch 18 is switched to the memory 7 side, and the scanning photoelectrically converted image signal of the original document is corrected from the contents of the memory 7 and used from the output of the amplifier 14. In the second case, when the output of the deviation detection circuit 21 indicates that the deviation value is greater than or equal to the specified value, the blank area of the inserted original is dirty;
Alternatively, assume that the reflectance is changing significantly, and without performing a write operation to the memory 7, the contents of the memory 17 up to now (this document is the first page after the device is in operation) are stored. In the case of an initial value written by the control circuit 22, the scanning photoelectrically converted output of the original is corrected.

After the second sheet, the same operation is performed using the data previously written to the memory 7 as the initial value of the correction data.

The following operations are completed in a period of about 2 to 10 scans of the photoelectric conversion element, so there is no need to stop the paper feeding operation during this period. There is no problem because there is little dirt and variation in reflectance.

FIG. 4 is a block diagram showing still another embodiment of the variation correction portion of the graphic input device according to the present invention.

The photoelectric conversion output 13 of the light receiving element array is amplified by an amplifier 23 at a constant amplification factor.

The output is converted into a digital value by the A/D converter 15 and input to the memory 7 through the digital arithmetic circuit 24 and switch 20. The output of the memory 7 is connected to the other input of the digital arithmetic circuit 24,
4 is A/D converted and corrected image signal 25
used as.

The image signal 25 is also input to a deviation detection circuit 26 , a deviation of the variation in the image signal 25 is detected, and the detected deviation is input to the control circuit 22 . The operation of the embodiment shown in FIG. 4 is almost the same as that of the embodiment shown in FIG. 3, and the differences will be mainly explained below. When the apparatus of this embodiment is put into operation, initial data is first written into the memory 17, and then a document to be read is inserted and its top blank area is scanned and photoelectrically converted, and the A/D converted signal and the memory are stored. The digital arithmetic circuit 24 performs an arithmetic operation for correcting variations based on the signal read out from the arithmetic circuit 17.

At this time, the deviation detection circuit 26 detects the deviation of the image signal 25, and outputs to the control circuit 22 whether the value of the deviation is greater than or equal to a specified value. If the deviation value is less than the specified value, the control circuit 22 writes the output of the A/D converter 15 to the memory 17 at the next scan of the light-receiving element array as correction data for the current document, and if it exceeds the specified value, it does not write to the memory 7. Try not to do it. That is, this embodiment differs greatly from the embodiment shown in FIG. 3 in that calculations for correcting variations and detecting deviations after correcting variations are performed by digital circuits. As explained above in each of the embodiments, the present invention detects the condition of the blank area at the top of the document (presence of dirt, large and medium variations in paper reflectance, etc.) and uses that area as a standard white document as variation correction data. If it can be used, use it as correction data, and if it cannot be used, use the initial value or the correction data that became available at the closest time to this manuscript in a manuscript before this manuscript. It is designed to be used as correction data, and there are few restrictions on the manuscripts to be inserted (not all manuscripts need to have a blank space at the top, or even if the blank space at the top is dirty and mixed with other manuscripts). It is possible to provide a graphic input device that is easy to operate (in particular, there is no need to insert a standard white document for variation correction into the device or operate the device to perform measurement operations).

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional graphic input device.
Figure 2 is an explanatory diagram showing variations in output level for each light-receiving element;
FIGS. 3 and 4 are block diagrams each showing an embodiment of the present invention. 13...Output, 14...Amplifier, 15
...A/D converter, 17...memory,
18・,182・・・・．・Fixed contact, 183...
...Movable contact, 19...Constant generation circuit, 20...
...Switch, 20-, ...Fixed contact, 20-2...
...Movable contact, 21... Deviation detection circuit, 22.
...Control circuit, 23...Amplifier, 24.
...Digital calculation circuit, 25 ... Image signal, 26 ... Deviation detection circuit. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A light receiving element array, means for storing the output level of the light receiving element array for each element, and an output of each light receiving element obtained by photoelectrically converting the portion of the form where no figure is drawn for each of the light receiving elements. means for correcting by multiplying the output level of each light-receiving element by the ratio C/X between level When the detected deviation value is larger than the specified value, the correction value of the output level of the light receiving element array is replaced by the previous value, or if no previous value exists, the initial value stored in the storage means. A graphic input device comprising means for storing in the storage means.