JPH0410754A - Method and device for removing afterimage of image signal and rapidly inputting the same signal - Google Patents

Abstract

PURPOSE:To make it possible to input an image at a high speed by removing an afterimage at the time of no inputting an image, and at the time of inputting the image, instantaneously receiving the image and then immediately outputting an image signal. CONSTITUTION:The image processor utilizing a CCD image sensor 1 inputs an image signal and then executes the arithmetic processing of the image signal by an inherent flow. Thus, an afterimage can be removed without requiring useless time by shielding a photodetecting face by an optical control means 3 while utilizing the above time and scanning an image at the maximum speed allowed of the image sensor 1. At the time of inputting the input signal, the photodetecting face is instantaneously turned to a photodetecting state by the means 3 and then a transfer clock (scanning start command) is forcedly applied to the sensor 1. Thereby, the image signal can be read out within the time of one scanning. Consequently, the afterimage can be removed without requiring useless time and the image signal can be rapidly inputted.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and apparatus for removing afterimages from image signals and inputting image signals at high speed in an image processing apparatus using an image storage type image sensor. .

[Prior Art] An image storage type image sensor is generally a CCD (Cha
It is called an image sensor (coupled device) and has an internal configuration as shown in FIG.

Each pixel (pho-I diode) is charged by light and due to the transfer lock, the charge charged up to that point passes through the shift gate 1 and is stored in the analog shift register at once. When the number of pixels is large, this analog shift register has two systems, one for even-numbered pixels and one for odd-numbered pixels, as shown in FIG. - Once the charge (image) is transferred to the analog shift register, each pixel continues to accumulate new charge in response to light until the next transfer lock is input. The image signal is output by applying a shift clock to an analog shift register. In other words, in synchronization with the shift clock after the transfer lock,
The charge (image) held by each pixel is discharged from the output terminal -f (buffer) in order from the first pixel. Since the buffer generally has a charging part, at the end of each pixel discharge, a reset clock is applied in preparation for the output of the next pixel.
Discharge the stored charge. Ideally, the charge charged in the photodiode would be completely transferred to the analog shift register, but some charge remains in the photodiode, which is a so-called afterimage phenomenon. If the above operation is not shown in time chart 1, it will be as shown in FIG.

Incidentally, the input of the image signal from the CCD image sensor as described above to an image processing device, etc., has generally been carried out as shown in FIG. The image signal is left out by repeating the transfer lock and the shift I clock (including the reset I clock), and the next transfer lock that appears in response to the input start signal is captured, and the image signals (each This method attempts to import the pixel output) into an external processing system. However, this method has the following drawbacks.

(1) If the input start signal and the transfer lock are at the same time, the input will be completed in the time of one scan (from one transfer lock to the next transfer lock, that is, the output period for all pixels), but the input If the start signal is transferred immediately after locking, it will take about two scans.

(2) Accurate image signals cannot be obtained because afterimages are constantly added.

On the other hand, a common method for removing afterimages is to shield the light-receiving surface from light, spit out the afterimage in several scans, store the image with the light-receiving surface in the light-receiving state during the subsequent scanning period, and then input the image signal in the next scan. (Figure 6). This has the advantage of being able to remove afterimages and obtain accurate image signals, but it requires several scans for afterimage processing, -scans for accumulation, and one scan for input in -times of input time. is necessary. For example, if the number of scans for afterimage processing is eight, five scans are required to input the image signal. As a way to reduce the scanning time required to remove this afterimage, in the case of an image processing device, there is time to calculate the image after inputting the image signal, so if the afterimage removal scan is performed within this time, it will be especially effective. Therefore, it is not necessary to perform afterimage removal scanning before inputting the image signal (Japanese Unexamined Patent Publication No. 132578/1983). Even in this case, since the image accumulation scanning time, output scanning time, and transfer lock waiting time are added, the maximum scanning time is required for image input.

[Problems to be Solved by the Invention] As described above, although the conventional methods take into consideration the removal of afterimages, they do not take into account the time required to input the image signal, and it is difficult to actually output the image signal. There is a problem in that it takes more time than the scanning period (-scanning period).

The purpose of the present invention is to remove afterimages without wasting time,
Another object of the present invention is to provide a method and apparatus for inputting image signals at high speed.

[Means for Solving the Problems] In order to achieve this object, the present invention removes afterimages when no image is input in a CCD image sensor, and instantaneously receives light (image accumulation) on the light receiving surface (imaging surface) during input. The purpose is to immediately output an image signal.

[Operation] After inputting an image signal, an image processing device using a CCD image sensor performs arithmetic processing on the image signal according to a unique flow. If the light-receiving surface is shielded from light by the light control means and the image sensor is scanned at the maximum speed allowed by the image sensor using this time, the afterimage can be removed without wasting time. When an image signal is input, the light-receiving surface is momentarily brought into a light-receiving state by the light control means, and then the image sensor is immediately forcibly transferred and locked (scanning start command), and one scanning period starts from this point. The image signal can be read out with .

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a time chart 1 showing the configuration of the present invention, and FIG. 2 is a time chart 1 showing the operation of the present invention.

In the figure, 1 is a CCD image sensor, 2 is an image signal scanning means for scanning the image sensor 1, 3 is a light control means for blocking or receiving light from the light receiving surface of the image sensor 1, and 4 is a light control means 3 5 is a scanning start control means for detecting the output from the pulse outputting means 4 and instructing the image signal scanning means 2 to start scanning; 6 is a scanning start control means from the image signal scanning means 2; Image sensor J that provides transfer lock, shift clock, etc.
7 is an image signal output from the image sensor 1, and 8 is a general image processing device that inputs and processes the image signal 7.

The present invention will be explained in detail below. The image signal scanning means 2 scans at the highest speed allowed by the image sensor 1. The image processing device 8 gives an instruction to the pulse output means 4 only when the image signal 7 is required.

Therefore, no instructions are usually given to the pulse output means 4, and no instructions are given even during calculation after the image processing device 8 inputs the image signal 7. The pulse output means 4 does not give a pulse signal to the light control means 3 unless instructed by the image processing device 8 . The light control means 3 applies light to the image sensor 1 only during the pulse period. During other periods, the light escapes or is blocked. The light control means includes, for example, a high-speed shutter or an A/○ (Acoust;j,c0ptic
a1. ) You can use a modulator. The area around the image sensor 1 is designed to shield disturbance light. By doing this, since the image sensor 1 is normally in a light shielding state, it enters an afterimage emission state. In FIG. 2, "afterimage discharge" corresponds to this. Afterimages are generally completely removed within a few scans. The image processing device 8 supplies a signal for starting image input to the pulse output means 4 when an image signal is required. The pulse output means 4 generates a pulse and supplies it to the light control means 3 to supply light to the image sensor 1 only during the pulse period. Since the pulse period is equal to the image accumulation time, it can be set in consideration of the light intensity and the attitude of the image sensor. The scanning start control means 2 detects the end of the pulse output from the pulse output means 4, and forces the image signal scanning means 2 to lock the transfer even if the timing is in the middle of scanning.
In other words, it commands to output a scan start command. If a transfer lock is applied during scanning, subsequent images remain in the analog shift register (see FIG. 3), but this does not pose any problem since the afterimage has already been completely removed. After the transfer lock is forcibly applied, the image sensor 1 immediately outputs the image signal 7 accumulated during the pulse period to the image processing device 8 by the subsequent shift clock. The shaded area in FIG. 2 corresponds to this. The image processing device 8 only needs to detect one scan after the pulse output from the pulse output means 4 and input the image signal 7. When the image signal 7 is output, the image sensor]- is already in a light-shielding state, so the afterimage discharge period begins again.

According to this embodiment, the image signal after the afterimage has been removed can be input at high speed by (light reception time of the image sensor) + (time for one scan).

[Effects of the Invention] According to the present invention, afterimages are removed during the non-input period of image signals,
When an image signal is input, the CCD image sensor receives pulsed light and the image signal can be obtained immediately, so that image input can be performed at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is a block diagram of the CCD image sensor, and FIG. 4 is a time chart showing the operation shown in FIG. Explanation of symbols 1... CCD image sensor, 2... Image signal scanning means, 3... Light control means, 4... Pulse output means, 5
...Scanning start control means, 8...Image processing device.

Claims (1)

[Claims] 1. In an image signal processing device using an image storage type image sensor, when no image signal is input, the light receiving part of the image storage type image sensor is placed in a light-shielding state, and an afterimage is forcibly removed by scanning. When exhaling and inputting, the light-receiving part is momentarily in the light-receiving state,
After receiving light, the images accumulated by receiving light are forcibly and immediately displayed.
A method for removing afterimages from an image signal and for high-speed input, the method comprising outputting the signal and inputting the signal to the image signal processing device. 2. A scanning means for scanning the output of the image storage type image sensor, a light control means for blocking and projecting light to the light receiving section of the image storage type image sensor, and a pulse signal is given to the light control means to control the pulse period. An image signal comprising: pulse output means for applying light to a light receiving section of the image storage type image sensor; and scan start control means for forcibly giving a command to the scanning means to start scanning after outputting the pulse. Afterimage removal and high-speed input device.