JPS60220478A - Image input device - Google Patents

Abstract

PURPOSE:To facilitate change of a sampling pitch and to utilize an amount of illumination light by controlling an adder/accumulator with the aid of a sampling pitch controller in accordance with a set pitch and a selected mode. CONSTITUTION:A picture element pitch (pitch for sampling a signal of each CCD sensor element 5) is set in a sampling pitch setting device 11. A sampling pitch controller 10 controls an adder/accumulator 9 in accordance with a set sampling pitch and a switching position of a mode switching device 12. Each digital value outputted from an A/D convertor 7 is inputted to the adder/accumulator 9 and outputted with the aid of a control of the sampling pitch controller 10. A digital signal outputted from the adder/accumulator 9 is simultaneously outputted from an output terminal 9b and returned to an input terminal 9a. Whether or not the signal is added at the switching position of the mode switching device 12 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image input device that optically reads image information and outputs the read image information as a digital image signal.

[Background of the invention]

Image input devices such as automatic drawing reading devices and OCR are devices that convert images themselves into image signals.

Then, for example, the image itself is stored by outputting this image signal to an image memory, and the stored image is used in various forms. An outline of such an image input device will be explained with reference to the drawings.

FIG. 1 is a system diagram of a conventional image input device.

In the figure, 1 is a drawing in which an image to be read is drawn.

The image is drawn in dots on a white surface. Reference numeral 2 denotes a lamp for illuminating the drawing 1, 3 an optical system comprising lenses, etc., and 4 an image sensor for detecting an optical input signal arriving from the drawing 1 via the optical system 3.

The image sensor 4 is configured by arranging a large number (for example, 1,500) of CCD sensor elements 5, and converts an optical input signal into a corresponding electric signal and outputs the electric signal. , 6 is an amplifier that amplifies the signal from the image sensor 4, 7 is an A/D converter that converts the analog output signal of the amplifier 6 into a digital signal, inverts it and outputs it, and 68 is an A/D converter that outputs the inverted signal. transfer lock, and A/D converter 7
This is a rip clock generator that outputs a conversion command clock for 1C.

FIG. 2 is an enlarged plan view of the image sensor shown in FIG. 1. In the figure, Ll is the distance between the light receiving elements 5, M is the light receiving width, L
, indicates the gap between the light receiving elements 5. The illustrated image sensor 4 is a line-type image sensor in which CCD sensor elements 5 are arranged in rows at intervals, and captures an image in one IC line (scanning line) on the drawing 1. The capture range is determined by the image sensor 4 in the scanning line.
This is the portion that exists within the portion detected by the CCD sensor elements 51+51 at both ends. Within this capture range, the area (pixel) detected by one CCD sensor element 5 is determined by the optical system 3 and the spacing between the light receiving elements.

Each CCD sensor element 5 converts the amount of light reflected from the corresponding picture element in FIG. 1 into an amount of electricity corresponding to the amount of light and temporarily stores it. Each of the stored electric quantities of each CCD sensor element 5, that is, the electric quantity of each picture element, is sequentially output from one side to the analog amplifier 6 as an electric signal by a transfer lock from the clock generator 8. The analog signal amplified by the amplifier 6 is converted into a digital signal by the A/D converter 7 at a predetermined timing based on a conversion command signal from the clock generator 8. After this converted digital signal is inverted,
For example, it is output to an image memory and stored there. That is, the image signals of each picture element on FIG. 1 are stored as corresponding digital values. By performing appropriate processing (image processing) on the values stored for each picture element, the same image as the image shown in FIG. 1 can be reproduced.

By the way, there are various types of images drawn on drawing 1, such as precise images drawn with thin lines and rough images drawn with thick lines. , and in order to be able to handle any of these images, it is clear that the number of picture elements per unit length on the scanning line should be increased (for example, 16 pixels), and the image sensor An image input device using 4 is constructed with this in mind. On the other hand, since the image processing requires high-speed processing, if the target is a coarse image or if the reproduced image can be a coarse image, the number of picture elements per unit length on the scanning line is small. This is advantageous because the amount of image information is smaller.

Flying spot sensors have conventionally been used as a means of resolving these conflicting demands. According to this flying spot sensor, by appropriately dividing the frequency of the position pulse of the scanner drive system, the pixel interval (sampling pitch) can be changed relatively easily, and the above-mentioned conflicting demands can be met. However, since the flying spot sensor is composed of a vacuum tube, it has drawbacks such as an increase in the size of the device and an increase in cost. Furthermore, in the case of an image input device using the CCD sensor element 5, the sampling pitch cannot be arbitrarily varied because the CCD sensor element 5 and the picture elements are in one-to-one correspondence. , drawing l, the relative distance between the lens of the optical system 3 and the CCD sensor element 5 is made variable, or the optical system 3 is provided with a combination of several lenses,
Means for changing the sampling pitch by changing the combination as necessary has been proposed.

However, such means is not preferable because it involves mechanical driving of the optical system, and also has the disadvantage that the apparatus becomes complicated and large-sized, resulting in a large increase in cost.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the above-mentioned conventional drawbacks and to provide an image input system in which the sampling pitch can be easily changed without changing the mechanism of the optical system. We are in the process of providing equipment.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized by providing sampling means for sampling analog or digital signals that are sequentially output based on the detection values of each photodetection element arranged at predetermined intervals. do.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 3 is a system diagram of an image input device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 9 is an adder/accumulator;
Depending on the command, the inverted digital signal output from the A/D converter 7 can be output as is, the value outputted last time can be added and outputted, or the value outputted before the last time can be accumulated. It has the function of outputting. Reference numeral 10 denotes a sampling pitch controller for controlling the adder/accumulator 9 to obtain a desired sampling pitch (picture element pitch) and sampling value, and is supplied with a timing signal by the clock generator 8. 11 is a sampling pitch controller 1
12 is a sampling pitch controller 10' that specifies the sampling pitch relative to 0;
This is a mode switch that instructs the VC to perform addition/accumulation.

Next, the operation of this embodiment will be explained with reference to the images and their waveform diagrams shown in FIGS.

Figure 4(a) is a plan view of the image, Figures 4(b) to [h]
is a waveform diagram showing the magnitude of a signal corresponding to the above image on a scanning line. Now, suppose that the image shown in FIG. 4 (al) is drawn in a certain part within the capture range on Drawing 1. In this case, each CCD cell corresponding to each pixel on the scanning line S of the illustrated image An electrical signal corresponding to the amount of reflected light from each picture element is sequentially extracted from the / element 5.
FIG. 4(b) shows the amplified signals of each CCD sensor 5 corresponding to each picture element of the image.

This signal is input to the A/D converter 7 and converted into a digital value, and the converted digital value is inverted and output. A waveform showing the magnitude of this inverted digital value is shown in FIG. 4(c). That is, the wheat converter 7 outputs a digital value with the white level and black level inverted.

Here, the sampling pitch setter 11 is set to one pixel pitch (all signals from each CCD sensor element 5 are sampled), and the mode switch 12 is switched to a position instructing not to add. Considering the case,
The sampling pitch controller lO adds an addition φ accumulator 9 according to the set sampling pitch and the switched position.
That is, each digital value outputted from the A/D converter 7 shown in FIG.
output as is under the control of In this case, for example,
The digital signal output from the adder accumulator 9.

is simultaneously outputted from the output terminal 9b and sent to the adder/accumulator 9.
However, since the mode switch 12 has been switched to the non-adding position, the sampling pitch controller 10 selects the signal D1 returned to the adder/accumulator 9 as the next input signal. Prevents VC from being added. Therefore, each signal 1 to D0 is output as is and stored in the image memory. After that, when performing image reproduction based on the stored signal, for example, if image processing is performed using the threshold value Da shown in FIG. 4(c), the pixel black level of the hatched part shown in FIG. 4(d) VC The image corresponding to each picture element on the scanning line S shown in FIG. 4(a) can be reproduced almost faithfully.

Next, set the sampling pitch setting device 11 to a two-pixel pitch (
In this case, the signal of each CCD sensor element 5 is sampled every other signal, and the mode is set to 1, and the mode is set to 1. think. In this case, the sampling pitch controller 1
0 does not output the signal DX input to the adder/accumulator 9 to the image memory, but returns it from the terminal 9b to the terminal 9a. Then, when the next signal) is input, the signal D
1 is added and this signal (D, +D,) is output to the image memory. Similarly, when the next signal D3 is not output to the image memory and the next signal D4 is input, the rabbit signal D3 is added to this signal D4, and this signal (Ds + Da
) to the image memory. The signal output from the adder/accumulator 9 in the above case is shown in FIG. 4(e). In this case, the number of image information to be captured is halved, and subsequent image processing can be performed at higher speed. In image processing, when the threshold value is set to the value Db shown in Fig. 4(e),
Corresponding to each picture element, a signal can be obtained that makes the black level of the picture element of the hatched part shown in FIG. 4ff) VC.

In this case, all the signals are reflected in the image information, and the amount of illumination light (that is, the sensitivity of the CCD sensor element 5) can be effectively used. There is a possibility that the so-called drawing collapse phenomenon may occur due to the lack of resolution when the image is cut.

Furthermore, let us consider a case where a two-pixel pitch is set in the sampling pitch setter 11 and the mode switch 12 is switched to a position that does not instruct addition, that is, a case where one pixel is thinned out one by one. In this case, the sampling pitch controller 10 controls the signal input to the adder/accumulator 9,
DB, Da, Ds are not sampled, and the signal D
z, D4, Ds, D7. Do is outputted from the adder/accumulator 9 without being added/accumulated with previous signals. This output signal is shown in FIG. 4(g). In this case, as in the case of the rabbit, the number of image information to be captured is halved, and image processing can be performed at high speed. In this image processing, the threshold value is set to the value shown in FIG. 4(g) Vc. When the VC is set, a signal is obtained for each picture element with the hatched part shown in Figure 4 (h) as the black level, and in this case, the part corresponding to the signal R appears without being cut. become.

Note that the pixel pitch set in the sampling pitch setting device and the switching position of the mode switch are not limited to the above example, and various pixel pitches and various addition/accumulation modes can be set depending on the image condition. You can choose. The sampling pitch controller is also timing controlled by a clock signal from the clock generator and outputs a strobe signal to the image memory that determines the digital value to be stored.

As described above, in this embodiment, the pixel pitch is set in the sampling/bring pitch setting device, the addition/accumulation mode is selected by the mode switch, and the sampling pitch is controlled according to the set pitch and the selected mode. Since the adder/accumulator is controlled by the device, the sampling pitch can be easily changed according to the image without changing the mechanism of the optical system. Furthermore, by appropriately performing addition and accumulation, the amount of illumination light can be used effectively.

In the above embodiments, an example in which sampling is performed on a digital signal has been described, but it is also possible to perform sampling on an analog signal output from an amplifier. Further, the pixel pitch setting of the sampling pitch setting device and the mode selection of the mode switching device are not limited to manual setting and selection. That is, if a device is provided that can judge the state of the image (thickness, thinness, etc. of lines), it is possible to automatically set the pitch and select the mode according to the judgment.

〔Effect of the invention〕

As described above, in the present invention, analog signals or digital signals that are sequentially used and inputted based on the shame detection values of the photodetecting elements arranged at predetermined intervals are processed by the sampling means at an appropriate pixel pitch according to the image. Since sampling is performed, the sampling pitch can be easily changed without changing the mechanism of the optical system.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional image input device, FIG. 2 is an enlarged plan view of the image sensor shown in FIG. 1, FIG. 3 is a system diagram of an image input device according to an embodiment of the present invention, and FIG. (a) is a plan view of a part of the image, Fig. 4 (b), (c), (dl,
(el, (fl, (gl, (hl) are waveform diagrams showing the magnitude of the signal corresponding to the image shown in FIG. 4 (al). 1...Drawing, 2...・Lamp, 3...
...Optical system, 4... Image sensor, 5...
...CCD sensor element, 6...Amplifier, 7
...A/D converter, 8...Clock generator, 9...Adder/accumulator, 10...
Sampling pitch controller, 11...Sampling pitch setting device, 12...Mode switching device.

Claims (1)

[Claims] In an image input device comprising photodetecting elements arranged at predetermined intervals and a signal processing means for sequentially outputting the output signals of each of these photodetecting elements as a digital signal, based on the detection value of each of the photodetecting elements, An image input device characterized in that it is provided with sampling means for sampling signals that are sequentially output.