JPS6351775A - Still image pickup camera - Google Patents

Abstract

PURPOSE:To obtain a sharp picture by outputting a drive signal to a liquid crystal driver through the designation of an address corresponding to a picture element level exceeding a setting level in response to a control signal from a level detection circuit. CONSTITUTION:When a level detection circuit 14 detects it that an external light having a brightness in excess of a setting level is made incident on any picture element of a CCD image pickup section 3, the level detection circuit output a control signal to the liquid crystal driver 16 attended therewith. Then a liquid crystal 15 at a position corresponding to a part of the picture element receiving an external light with a high brightness is driven, the transmission quantity of the external light is decreased to reduce the brightness level of the external light made incident on the CCD image pickup section more than the setting level. Thus, even if the external light having the brightness in excess of the setting level is made incident, the brightness of the external light is reduced up to a brightness less than the setting level and then made incident on the CCD image pickup section 3, then the occurrence of smear due to the local incidence of light with high brightness is prevented and a sharp picture is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to photographing a license plate of a vehicle in order to identify the vehicle and measure its running speed, etc.
For more information on static imaging cameras used for photographing products for product inspection, etc., please refer to CCD
A CCD solid-state imaging device consisting of an imaging section, a CCD storage section, and a horizontal shift renostar, and a CCD storage section that outputs a vertical synchronization signal and, in response to the vertical synchronization No. 13, stores one field's worth of accumulated signal charge in the CCD imaging section. The present invention relates to an FT (frame transfer) type static motion camera, which is equipped with a timing generator that outputs a first transfer pulse to be transferred to a frame transfer camera.

(Prior art and its problems) In this type of conventional stationary V&elephant camera, if even one point of locally high brightness light is incident on the CCD imaging unit, smear occurs due to the light. The pixel where the phenomenon occurs and the high-intensity light is incident is affected not only by the surrounding pixels, but there is a drawback that the image is lost mainly at the point where the high-intensity light is incident.

Therefore, in the past, photographic lenses were generally equipped with an aperture section.
When high-intensity light is incident, the amount of light incident on the CCI) imaging section is adjusted by operating the aperture section.

However, in the case of a conventional example with such a configuration, it is effective when light with a brightness of the entire CCDCD image pickup body is incident, but when locally high-luminance light is incident, the overall brightness is adjusted according to the light. It was narrowed down to C.
This has the drawback that the amount of light incident on the CD imaging section is reduced overall, resulting in an overall dark and unclear image.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to locally adjust the amount of light incident on the CCD imaging section, thereby providing locally high brightness to the CCD imaging section. To be able to obtain clear images even when the light of
target

(Structure and Effects of the Invention) In order to achieve such an object, the present invention provides the static imaging camera described at the beginning, in which the amount of external light transmitted to each pixel of the CCD imaging unit in the driving state + decreases. Detects the brightness of external light input to each of the pixels of the liquid crystal, the liquid crystal driver that drives the liquid crystal, and the CCD imaging section, and outputs a control signal when the brightness level of the detected external light exceeds a set level. and a control means for specifying an address corresponding to a pixel exceeding the set level in response to the control signal and outputting a drive signal to the liquid crystal driver.

According to this configuration, when the level detection circuit detects that external light with a brightness exceeding a set level is incident on any pixel of the CCPL image section, the level detection circuit accordingly sends a control signal to the liquid crystal driver. It outputs a value of can be reduced.

Therefore, when external light with a brightness that exceeds the set level is incident, the brightness of the external light is reduced by the liquid crystal to a brightness that is lower than the set level and then enters the CCD imaging section. It is possible to prevent the occurrence of smear phenomenon caused by incident light, and in addition, when high-intensity external light is locally incident, the brightness of the incident light can be controlled by CC.
The entire DCD image pickup body is reduced, because there is nothing to do.
It is now possible to maintain a predetermined brightness for the entire image and obtain a clear image.

In addition, even if high-intensity external light is incident on the entire ccDa image area, it will be detected that the setting level has been exceeded in a wide range or all pixels of the CCD imaging area, and the area corresponding to those pixels will be detected. Since the amount of light transmitted is reduced by driving the liquid crystal of Clear images can be obtained regardless of whether it is the entire imaging area or only locally.
It has become possible to provide still cameras that are extremely useful in practical terms.

(Description of Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 is a schematic configuration diagram of a still imaging camera according to an embodiment of the present invention. In this figure, 1 is a photographic lens, and 2 is a CCD solid-state image sensor, which converts an optical signal incident through the photographic lens 1 into an electrical signal.

The CCD solid-state imaging device 2 includes a CCD imaging section 3 and a CC
A D storage section 4 and a horizontal shift register 57 are provided, and a CC
In the D imaging section 3, signal charges photoelectrically converted according to the brightness of the incident light are accumulated, and the CCD imaging section 3
Among the image data accumulated in the C, the image data (signal charge) for the horizontal line is transferred 4 times to the COD accumulation by inputting one clock of the first transfer pulse P1, and then transferred to the C
Image data (signal charge) for one horizontal line in the OD storage section 4 is transferred to the horizontal shift register 5 by inputting one clock of the second transfer pulse Ps, and a set number of first transfer pulses Pi and second transfer pulses Ps are transferred. By each, C.C.
One field's worth of accumulated signal charges in the D imaging section 3 is transferred to the CCD accumulating section 4, and at the same time, four fields' worth of signal charges on the COD accumulation are transferred to the horizontal shift register 5.

Furthermore, the image data for 1 fields transferred to the horizontal shift reno star 5 is transferred to the outside by inputting the third transfer pulse T.

Reference numeral 6 denotes a timing generator, which outputs a vertical synchronizing signal VD and a horizontal synchronizing signal HD, and also outputs the first transfer pulse Pi and the second transfer pulse Ps in response to the vertical synchronizing signal VD. , and outputs the third transfer pulse T.

A counter 7 is configured to count the horizontal synchronization signal 11D while being cleared by inputting the vertical synchronization signal VD, and the counter 7 has a set value and is configured to count the horizontal synchronization signal 11D. A start signal is output when the count values match. This setting value is
It is set to a value smaller than the number of horizontal synchronization signals HD in the I field period, and the set value can be changed.

8 is a COD clear pulse generating section, and the counter 7
COD photographing unit a 3 and COD
In terms of accumulation, a number of clear pulses CP greater than the number of pixels of each of the four pixels is generated, and the signal charges remaining or accumulated in the CCDCD impression section and the CCD accumulation section 4 are transferred and cleared.

The output terminal from the COD clear pulse generator 8 is connected to the input terminals of first and second OR gates 9.10, and the other input terminal of the first OR gate 9 is connected to the first transfer signal from the timing generator 6. The output terminal of the pulse Pi is connected, and the output terminal of the second transfer pulse Ps from the timing generator 6 is connected to the other input terminal of the second OR gate 10. 1
The output terminal 0 is connected to the driver 11.

The signal charge transferred from the horizontal shift register 5 is
The signal is amplified through the amplifying section 12, converted into a video signal by the signal processing section 13, and output.

Reference numeral 14 denotes a level detection circuit, which detects the brightness of external light based on the video signal from the signal processing section 13. Specifically, the level of the video signal is compared with a threshold level (set level) set to a predetermined level, and when the level exceeds the threshold level,
A high-intensity signal as a control signal is output to the timing generator 6.

Reference numeral 15 denotes a liquid crystal, which is provided between the photographing lens l and the CCD p image section 3 of the CCD solid-state image sensor 2, and has an electrode section corresponding to each pixel of the CCD image sensor 3, as shown in FIG. By driving the liquid crystal driver 16, a voltage is applied to the electrode section at a predetermined address to reduce the amount of external light transmitted there.

The timing generating section 6 is equipped with a control means, and in response to a high-intensity signal (control signal) from the level detection circuit 14, setting is performed based on the horizontal synchronizing signal 1-ID and the third transfer pulse T. A drive signal is output to the liquid crystal driver 16 by specifying an address corresponding to the pixel exceeding the level.

That is, as shown in FIG. 3(a), when high-intensity external light is incident on a part A of the CCD imaging section 3, the video signal output from the signal processing section 13 in response to the high-intensity external light is As shown in FIG. 3(b), a smear phenomenon occurs in the portion B corresponding to the point where the high-intensity external light is incident, and the image becomes unclear. By passing this high-intensity external light through the liquid crystal 15 in the driven state and reducing the amount of light transmitted, the brightness when it enters the CCD imaging section 3 is reduced.

Next, the operation of this embodiment will be explained using the time charts of FIGS. 4 and 5.

In response to the output of the vertical synchronizing signal VD as shown in FIG. 1(a), the horizontal synchronizing signal 1 (as shown in FIG. 4(b)
When D is output, at the same time, the third transfer pulse T is output to the horizontal knot register 5, and the video signal is taken out via the signal processing section 13, as shown in FIG. 4(C).

The video signal is input to the level detection circuit I4 and compared with a threshold level, and when it exceeds the threshold level, a high brightness signal as a control signal is output as shown in FIG. 4(d).

In the level detection circuit 4, as shown in the time chart in which the time axis of the video signal is enlarged in FIG. The video signal exceeding threshold level 1 corresponds to the number of pulses of T [see Figure 5<b]].
(see figure (c))] and detects the high-intensity signal [see figure 5 (
d)], and after outputting the high brightness signal, the threshold level 2 is set to a lower value than the threshold level 1.
It is designed to stop outputting the high-intensity signal when the brightness becomes lower than that.

The output state of the high-intensity signal will be explained in detail using the cases shown in FIGS. 5(b) and 5(C) as examples.
A high brightness signal is output in each of r) and (r+3).

As this high-intensity signal is input to the timing generation section 6, the number of vertical synchronization signals VD at that time (nth) and the number of pulses (r) and (r + 3) of the third transfer pulses T become timing The generation unit 6 reads the drive signal, and outputs the corresponding drive signal to the liquid crystal driver 16, and as shown in FIG. , (r+3) are specified and a voltage is applied, and when viewed from the front, CCDC
The amount of light transmitted at addresses XI and X2 corresponding to the n-th pixel from the top of the D imaging unit, the first pixel from the left, and the r+3-th pixel from the left is reduced.

Then, when the level of the video signal from the CCDCD imaging unit corresponding to the above address becomes lower than threshold level 2 due to a change in the brightness of external light,
The output of the high-luminance signal is suddenly stopped, and in response, the output of the drive signal to the liquid crystal driver I6 is stopped, and the application of voltage is stopped.

As a result, even if high-intensity light is incident on the part, the luminance can be reduced by the liquid crystal 15 before being directed onto the CCDCD imaging section.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a static imaging camera according to an embodiment of the present invention, FIG. 2 is a perspective view showing the liquid crystal part, and FIG. 3 is a
A diagram explaining the relationship between high-intensity light and a video signal, FIGS. 4 and 5 are time charts explaining the operation of the embodiment, and FIG. 6 is a front view explaining the driving state of the liquid crystal. It is. 2...Solid-state image sensor, 3...CCD imaging vibration 4...COD storage section, 5...Horizontal soft register, 6...Timing generation section, 1.1...Level detection circuit, 15.Liquid crystal, 16...LCD driver.

Claims (1)

[Claims] (1) A CCD solid-state imaging device consisting of a CCD imaging section, a CCD storage section, and a horizontal shift register;
A still imaging camera comprising: a timing generator for outputting a first transfer pulse for transferring accumulated signal charges for one field of a CD imaging section to a CCD storage section; a liquid crystal that reduces the amount of external light transmitted through the liquid crystal; a liquid crystal driver that drives the liquid crystal; and a liquid crystal driver that drives the liquid crystal, and detects the brightness of the external light input to each pixel of the CCD imaging section, and adjusts the brightness level of the detected external light to a set level. a level detection circuit that outputs a control signal when the set level is exceeded; and a control means that responds to the control signal and outputs a drive signal to the liquid crystal driver by specifying an address corresponding to the pixel that has exceeded the set level. A still imaging camera with