JPS62107579A - Picture input device - Google Patents

Abstract

PURPOSE:To obtain picture data with high accuracy without being affected by temperatures and circumstances by providing a light shielding means for reflected light, a memory circuit storing a measured dark current at the time of blocking light and a subtractor circuit, as well as a photoelectric converter element, an A/D converter and a picture data memory. CONSTITUTION:Prior to inputting picture data to a CCD 1, a shutter 4 acts so as to block reflected light, and the dark current of the CCD 1 is caused accordingly. A read circuit 7 reads out the dark current and inputs it to the A/D converter 2. The digitized dark current is inputted to the memory circuit, that is, a RAM 5, for instance. Upon the completion of reading the dark current, the shutter 4 is opened, and irradiates the reflected light 1-3 of an object 1-2 to the CCD 1. The read circuit 7 reads out the contents of the CCD 1, and inputs them to the A/D converter 2, which inputs the digitized picture data to the picture data memory 3. The subtractor circuit 6 subtracts the contents in the picture data memory 3 and the RAM 5, and the subtracted contents turn out to be picture data.

Description

[Detailed Description of the Invention] [Summary] An image input device comprising a photoelectric conversion element that receives reflected light from an object and an image data memory that reads the photoelectric conversion element, performs A/D conversion, and stores the image data. The input device is equipped with a light blocking means that blocks reflected light every time the photoelectric conversion element is read, and a memory circuit that stores the dark current value, and the dark current is subtracted and output every time the dark current is read. This makes it possible to obtain image data that is not normally used.

[Industrial application field]

The present invention relates to an image input device, and more particularly to an image input device that obtains image data that is not affected by the environment.

Image processing devices are widely used in fields such as information processing and communications.

One of them is an image input device. An image input device receives reflected light from an object at a photoelectric conversion element, and creates image data based on the converted current value. However, the dark current of a photoelectric conversion element is affected by ambient temperature. For example, in the case of a charge-coupled device (C(:D)), the temperature is 5
If the temperature rises by 8 degrees Celsius, the variation will be about twice as much, and if each element of the CCD is raised by 8 degrees Celsius, the variation will be about twice as much. Therefore, there is a need for an image input device that is not affected by changes in environmental temperature.

[Conventional technology]

The image input device is an A/D device that converts reflected light irradiated onto an object into an electrical signal using a photoelectric conversion element, such as a charge-coupled device (CCl4), and reads this and converts it into a digital signal.
The image data is stored in the memory via the converter. Image data will be read from this image memory. This image data is a value including the dark current of the CCD. Conventional devices measure this dark current by blocking reflected light before obtaining image data, and then subtract this dark current from the above-mentioned image data to obtain the required image data using a method called (7). was hiring.

[Problem that the invention seeks to solve]

This conventional image input device 1) only measures one current before obtaining image data, and is manufactured on the assumption that the dark current is constant; therefore, the dark current varies depending on the environmental temperature. There was a problem in that the image data was not accurate because no correction was performed.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional situation, it is an object of the present invention to provide an image input device that can perform accurate dark current correction regardless of environmental temperature.

[Means for solving problems]

In the image input device of the present invention, as shown in FIG. a light blocking means 4 for the reflected light from the object, a memory circuit 5 for storing the measured dark current at the time of light blocking, and a subtraction circuit 6 for subtracting the stored value between the memory circuit 5 and the image memory 3. It is set up.

[Effect]

Each time the photoelectric conversion element 1 is read, the dark current is measured and the measured dark current value is subtracted from the value stored in the image data memory 3, resulting in image data that has been corrected due to the ever-changing dark current.

〔Example〕

FIG. 1 is a block diagram of essential parts of an embodiment of an image input device according to the present invention.

The object 1-2 is irradiated with the light source 1-1, and the reflected light 1-3 generated by the brightness of the object is transmitted through the optical system 1-4 and the shutter 4, which acts as a light blocking means, to act as a photoelectric conversion means. The light is received by a charge-coupled device (hereinafter referred to as CCD) 1.

Prior to inputting image data to the CCD 1, the shutter 4 operates to block reflected light, causing a dark current in the CCD 1. This dark current is read out by the continuous output circuit 7, and the A/
Input to D converter 2. The digitized dark current is input to a storage circuit, for example, RAM 5.

When the reading of the dark current is completed, the shutter 4 is opened and the CCr) 1 is irradiated with the reflected light 1-3 from the object 1-2. The content of this CCD I is read out by the output circuit 7 and inputted to the A/D converter 2, and the image data digitized by the A/D converter 2 is inputted to the image data memory 3.

The contents of the above-mentioned image data memory 3 and RAM 5 are subtracted by a subtraction circuit 6 to obtain image data. Note that the above-mentioned shutter 4 is, for example, a rotating disk, and this disk is composed of a window through which the reflected light 1-3 passes and a portion that blocks the reflected light 1-3. Furthermore, the control circuit 8 is in charge of controlling each of the above-mentioned parts.

FIG. 2 shows the state of the image data of the present invention described above. That is, the RAM 5 stores the dark current as shown in (bl) so as to correspond to the CCD 1. On the other hand, the image data memory 3 stores the image data as shown in (al), and the subtraction circuit 6 stores the dark current as shown in (al). is read and subtracted, and the temperature-corrected image data shown in (C) is output.

FIG. 3 is a block diagram showing another embodiment according to the present invention, and the difference from the embodiment is that the 00/1° image data memory 3 and the storage circuit 5 have a two-dimensional configuration. However, it goes without saying that the image data memory 3 only needs to be able to synchronize the subtraction process even if the image data memory 3 is for at least one pixel.

〔Effect of the invention〕

As described above, according to the present invention, image data with accurate temperature correction can be obtained without being affected by environmental temperature with an extremely simple configuration, and is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the image input device according to the present invention. FIG. 2 is a schematic diagram showing the state of image data according to the present invention. FIG. 3 is a block diagram of another embodiment of the image input device according to the present invention. It is. In the figure, ■ is a CCD, 1-2 is an object, 2 is a to/D converter, 3 is an image data memory, 4 is a shutter, and 5
6 indicates a RAM, and 6 indicates a subtraction circuit. c3-O

Claims (1)

[Claims] A photoelectric conversion element (1) that receives reflected light from a target object and an A/D converter (2) that converts the output of the photoelectric conversion element from analog to digital.
) and an image data memory (3) that stores the output of the A/D converter (2), wherein the image input device includes a light blocking device that blocks the reflected light every time the photoelectric conversion element (1) is read. means (4); a memory circuit (5) for storing the output of the A/D converter (2) read when the light blocking means (4) is activated; the image data memory (3); An image input device comprising: a subtraction circuit (6) for subtracting each stored value of the storage circuit (5).