JPS60158789A - Radiation resistant color television camera - Google Patents

Abstract

PURPOSE:To obtain a radiation resistant color television camera capable of being used in a high dosagel atmosphere by obtaining the difference between a black level when radiation is not incident and a luminance signal level after the emission of the radiation and by correcting a photographing level by the obtained quantity. CONSTITUTION:Only when a correcting action signal 505, that is, an operational signl of an operator, is ''1'', an output 508 is outputted from an AND circuit 504, which causes a relay drive circuit 503 to act, and a contact 57 is closed. At the same time, a signal holding circuit 51 is triggered. Then the circuit 51 fetches an output SBX-SBO of a subtractor 55. Here, the SBO is a black luminance signal level 54 when radiation is not incident and set by a variable resistance 55. The SBX is a luminance signal level after the emission of the radiation and set by the variable resistance 55. The circuit 51 holds the fetched output level SBX-SBO until the following correcting action is selected. Afterward, the level SBX-SBO is added to a photographing level by an adder 52, and a luminance signal after correction can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a color television (hereinafter abbreviated as TV) camera that can be used in a radiation atmosphere.

[Background of the invention]

Conventional color TV cameras with an integrated camera control unit (hereinafter abbreviated as CCU) begin to experience deterioration in color reproducibility and brightness signal level at 10" Radg irradiation dose due to gamma ray radiation damage. 103~10' due to loss of imaging function as a color TV camera.
High dose of Rad or higher (hereinafter, high dose is 103 to 104
It has the disadvantage that it cannot be used in areas (more than FLad).

[Purpose of the invention]

Therefore, it is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art by correcting the deterioration of the luminance signal level due to radiation damage, and to provide a radiation-resistant color TV camera that can be used even in a high-dose atmosphere. be.

[Summary of the invention]

The present invention will be explained in detail using FIG. FIG. 1 is a block diagram when the present invention is applied to a color TV camera that uses an image pickup tube as an imaging device and adopts a frequency separation method as a color imaging method. Solid line is color T
Among the constituent blocks of the V camera, conventional ones are shown, and the broken line is the luminance signal level correction circuit 5 of the present invention. In the conventional color TV camera, as shown in the graph of FIG. 2, the brightness signal level S decreases as the integrated dose increases. This is considered to be due to a decrease in the transmittance of the glasses used in the lens 2 and the image pickup tube 3 and a decrease in the amplification factor of the amplifiers used in the luminance signal processing circuit 6. In the two graphs in Figure 2, when the color pattern shown in Figure 3 is all subject 1, the solid line 8w represents the white luminance signal level (white luminance signal) t- of the color pattern, and the broken line Sm represents the black The luminance signal level (black luminance signal level) 't- is shown. As a result of the irradiation test, it was found that the following relationship exists between the white luminance signal level 8wx and the black luminance signal level 8mx after xR irradiation, regardless of the irradiation dose rate.

Swx Swo=Smx 8110 - Old" (1) However, Swo: White luminance signal when not irradiated. Smo: Black luminance signal when not irradiated. Therefore, the influence of radiation damage on the luminance signal S is The luminance signal Sx after xR irradiation can be corrected as follows using the black luminance signal level or the white luminance signal level since the luminance signal Sx is equal from the level to the white level.

When referring to the black luminance signal level; 8x + = Sx + (88X - 8oio) ... mark (2), Sxt: luminance signal level after correction Sx
: Luminance signal level before correction When referring to white luminance signal level; 5xr=Sx+(Swx 5BO), -”...
・'f3) Therefore, the present invention uses pure silica glass or radiation-resistant class doped with Ce (cerium) for the glass used for the lens 2 and the image pickup tube 3, and makes it resistant to the synchronization signal generation circuit 4, etc. A brightness signal level correction circuit that uses a radioactive bipolar element to improve the radiation resistance of the entire color TV camera, and satisfies formula (2) or formula (3) to prevent a decrease in brightness signal level due to radiation damage. By providing this, the radiation resistance of the color TV camera is further improved.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on examples.

First, an overview of the operation of a color TV camera will be explained using FIG. The color TV camera uses its imaging method,
Depending on the number of image pickup tubes, 3-tube color TV camera,
It can be divided into phase-separated two-tube color TV cameras, single frequency-separated single-tube color TV cameras, etc. Here, a single frequency separation single tube color TV camera will be explained as an example.

An image of an object 1' (i-lens 2) is focused on the photocathode of an image pickup tube 3. An example of the image pickup tube 3 is shown in FIG.

Incident light 31 passes through a crystal filter 32 and then passes through a color filter 3.
The face plate glass 33 to which the lens 7 is attached has color information and is imaged onto the target surface 34. By scanning this image with an electron beam (36) emitted from the cathode 35, a video signal is extracted through the transparent conductive film 38t. Figure 5 shows
3 is a diagram showing a state in which a color filter 37 is installed on a face plate glass 33. FIG. Figure 6 shows the line AA' in Figure 5.
A cross-sectional view in the direction of arrows is shown. The color filter 37 includes a yellow stripe filter 371 of transparent and yellow (blue does not pass, complementary color of blue) and transparent and cyan (red does not pass, complementary color of red).
The pitch of the two rice varieties of the cyan stripe filter 372 (
filters with the same stripe frequency) are crossed. However, as shown in FIG. 7, the cross filter is such that the phase of the video signal SL obtained from the image pickup tube through this filter changes by π/2 for each scanning line. The color information signal modulated at the frequency of this stripe filter becomes only the color information signal by the bandpass filter 71 according to the stripe frequency. (L in Figure 7)
Assuming that 25 cyan and yellow stripe filters have almost the same color information, the output signals of the 25 cyan and yellow stripe filters are a, A and A, respectively, corresponding to the scanning lines LH and Ls, as shown in FIG. So, it becomes B. Scan fj L 1 and L
Since the phase of each stripe filter is shifted by π/2 with respect to scanning line L3. By shifting ±i and adding it to the scanning line L1, one color component disappears and the other color component doubles. In the case of FIG. 7, when the light is advanced by π/2, only the cyan side, that is, the red component remains, and the yellow side, that is, the blue component disappears. Conversely, if it is delayed by π/2, only the blue component will be present. Such processing is performed by a scanning line delay circuit 72, a ±i phase shifter 73, a red component demodulation circuit 74, and a blue component demodulation circuit 75.
It is carried out in

76 and 77 are copper component process amplifiers.

On the other hand, the low frequency component representing the luminance signal is determined as follows. The cyan stripe filter 372 allows line components and blue components (CB) to pass through all parts. In addition, the yellow stripe filter 371 has green components and red components (R
) passes. Therefore, the green component passes through all parts of the two-layered cross-shaped filter. On the other hand, the red component is obtained from the transparent portion of the first cyan stripe filter 372 because it does not pass through the cyan portion. Also, since the blue component does not pass through the negative portion of the second yellow stripe filter, it is obtained only from the transparent portion of the second yellow stripe filter. In this way, both the red component and the blue component are reduced to 1/2 of the original incident light, and the low frequency component of the video signal output, which is the output of the low pass filter 81, is (o-+4R+-LB). is obtained. Then, a luminance signal is obtained through a luminance signal processing circuit 6 consisting of two process amplifiers.

The red component signal and blue component signal thus obtained are processed in a matrix 79 into an orange Lucian component with high color difference visual acuity, that is, a 1-axis component, and a green to violet component with low color difference visual acuity, that is, a Q-axis component. With the encoder 80,
A composite video signal that also includes a periodic signal is sent to the monitor. - In the case of a color TV camera, the three primary colors (in addition, green,
Luminance signals, including blue), also have a large impact on color reproducibility.

Correcting this reduction in luminance signal level due to radiation damage will greatly improve the performance of color TV cameras.

FIG. 8 is a conceptual diagram of a first embodiment of the present invention, and FIG. 9 shows an embodiment of a luminance signal level correction circuit corresponding to the first embodiment. FIG. 8 shows a method for correcting the luminance signal level S according to equation (2), in which the brightness signal level S is corrected by referring to black in the color pattern shown in FIG. In order to perform the correction accurately, it is necessary to perform the correction by applying the same illuminance 'Jk to the same place. Therefore, when a color TV camera is mounted on a device such as a mobile inspection device, a color pattern is installed at a standby position, etc., and the camera is always corrected at that position.

Then, the correction amount is determined based on the black luminance signal Vbell indicating the black of the power 2-pattern. Darkness signal level 54 (when not irradiated)
Smo) is set by a variable resistor 55.

The subtracter 55 calculates the luminance signal levels Sx and Smo after xi irradiation.
Calculate the difference (8x S'mo). For correction, ax needs to be at the black luminance signal level Smx. For this purpose, "black" t on the color pattern is used. If the numbers of the scanning lines corresponding to 1 black" on the color pattern are Lit to La2 ('Lmz>Lmt), for example, taking the average, a pulse is generated at the position of the scanning line number i (Ls1 to L12). As in counter 501,
The horizontal synchronizing signal pulses output from the synchronizing signal generating circuit 4 are counted.

Counter 501 is reset by vertical synchronization signal 59.

In response to the pulse 506 from the counter 501, the correction permission signal generation circuit 502 generates a correction permission signal 507 at the timing shown in FIG. Time 1. is the scanning time from the left edge of the color pattern to the center of the black pattern. Correction operation signal 505 which is an operator operation signal
Output 50 from AND gate 504 only when is logic “1”
8 is output, operating the relay drive circuit 503 and closing the contact 57, and at the same time triggering the signal hold 51. At this time, the signal hold circuit 51 outputs the subtracter output C3sx-
8) The content is held until the next correction operation is selected. Thereafter, the brightness signal level Sx obtained by photographing the subject 1 and the output of the signal hold circuit 51, that is, (8mx S++o) are added by the adder 52, and the corrected brightness signal Sx, is obtained.

In the method described above, the amount of correction due to radiation damage is determined by the black luminance signal level according to equation (2), but similarly, equation (3) is used to calculate the amount of correction due to radiation damage.
It is also possible to correct the white luminance signal level based on the white luminance signal level. In that case, the signal 54 is at the white luminance signal level 8WO when not irradiated, and the counter 501 is set so that the output signal pulse 506 of the counter 501 is output when there is 1 white on the color pattern, and the time t1 is obtained. It is sufficient to set the scanning feed so that it is centered on the white pattern.

FIG. 11 shows an embodiment of a luminance signal level correction circuit that uses point level masks 341 at both ends or the other end of the target surface 34 in FIG. 12 to correct the luminance signal level. The thirteenth factor shows the composite video signal 8F of the luminance signal corresponding to the scanning line. 56 is a horizontal synchronizing signal, 342 is a black level mask signal corresponding to the black level mask 341, and a dashed line 514 indicates the pedestal level. The trigger generation circuit 511 outputs a trigger pulse 512'Jk whose width is narrower than that of the thermal level mask signal 342 at the rising edge of the horizontal synchronization signal 56. Due to the trigger pulse 512, the relay drive circuit 503 operates,
The signal hold circuit 51 is caused to hold the output of the subtracter. In this embodiment, a black level mask 341 on the target surface 34 is used to obtain a black luminance signal level of 8mx'.

The signal obtained by the black level mask 341 does not include the effects of radiation damage to the lens 2. Therefore, it is necessary to correct the effects of radiation damage on the lens 2. 5
8 is the lens deterioration correction time i. Letting ktm be the ratio of radiation damage Et of the lens 2 to radiation damage Et of other electrical components, k t@ can be expressed by equation (4).

k a t − E t / E e ・・・・・・・
(4) Therefore, in the lens deterioration amount correction circuit 5'8, the output sound of the signal hold circuit is multiplied by (1+,z)', and the V lens 2 deterioration cover is also corrected. Then, in the adder 52, as in the first embodiment, the luminance signal level S is calculated according to equation (2).
Correct x.

In the detailed description of the present invention using the above drawings, the insertion position of the luminance signal level correction circuit 5 was set between the luminance signal processing circuit 6 and the encoder 80. A similar effect can be obtained by inserting it into the output of the encoder 80. - [Effects of the Invention] As explained above, according to the present invention, pure silica glass or Ce
By using radiation-resistant glass doped with (cerium) and using radiation-resistant bipolar elements in the synchronization signal generation circuit, etc., the radiation resistance of the entire color TV camera is improved, and the brightness signal level due to radiation damage is improved. By providing a luminance signal level correction circuit for correcting the decrease in the brightness, it is possible to provide a color TV camera with further radiation resistance.

[Brief explanation of drawings]

FIG. 1 shows the present invention in a single-frequency separation single-tube color TV.
A block diagram of a radiation-resistant color TV camera when applied to a camera. FIG. 2 is a diagram showing the irradiation characteristics of the luminance signal level with respect to the integrated dose. FIG. 3 is a diagram showing the color pattern. FIG. 5 is a diagram showing an example of an image pickup tube, and FIG. 5 is a diagram showing a color filter mounted on a face plate glass.
FIG. 6 is a diagram showing an arrow view on the AA' cross section in FIG. 5, FIG. 7 is a principle diagram of hue signal separation in a single frequency separation method, and FIG. FIG. 9 is a diagram showing an embodiment of the luminance signal level correction circuit of the present invention corresponding to the first embodiment, and FIG. 10 is a conceptual diagram of the luminance signal level of the first embodiment. FIG. 11, a diagram showing the timing diagram of the correction circuit, shows an embodiment of the luminance signal level correction circuit that uses all of the black level masks to correct the luminance signal level when there is a black level mask at both ends or the other end of the target surface. 12 shows a target surface with a black level mask, and FIG. 13 shows a composite video signal of luminance signals corresponding to scanning lines. 2... Lens, 3... Image pickup tube, 4... Synchronization signal generation circuit, 5... Luminance signal level correction circuit, 6... Luminance signal processing circuit, 71... Bandpass filter, 72...・・・
Scanning line delay circuit, 73...±π/2 phase shifter, 74...
・Red component demodulation circuit, 75...Blue component demodulation circuit, 76・
...Red component process amplifier, 77...Blue component process amplifier, 79...Matrix, 80...Enmerder, 32...Crystal filter, 33...Front plate glass,
34...Target surface, 35...Cathode, 36...
...electron beam, 37...color filter, 38...transparent conductive film, -51...signal hold circuit, 52...
Adder, 53... Subtracter, 55... Variable resistor, 58
...Lens deterioration amount correction circuit, 501...Counter,
502... Correction permission signal generation circuit, 503... Relay drive circuit, 504... AND gate, 511...
Trigger generation circuit. Agent Patent Attorney Akio Takahashi Name 1 Nomo 2 No. 5 Mi No. 6 Mi No. 70 No. 8 Nitsu Atsushi 951] No. 10 Kuchi No. 110 Katsu 120 No. 130 Continued from page 1 0 Inventor Sat 1) Ken 2 Hitachi Ichimoriyama-cho l research institute

Claims (1)

[Claims] 1. A radiation-resistant color TV camera, characterized in that the color TV camera is provided with a luminance signal level correction circuit for correcting a decrease in luminance signal level due to radiation damage. 2. Claim 1, characterized in that the luminance signal level correction circuit is provided between the luminance signal processing circuit encoder.
The radiation-resistant color TV camera described in Section 1. 3. The radiation-resistant color TV camera according to claim 1, characterized in that a luminance signal level correction circuit is provided after the encoder. . 4. A timing circuit that uses the luminance signal level correction circuit to select all black positions when a color pattern or monochrome pattern is viewed, and a subtractor that calculates the difference between the black level signal at that time and the black level signal when not illuminated. Claim 1: The invention is comprised of a signal hold circuit that uses the output of the timing circuit as a trigger, a signal hold circuit that holds the output of the subtracter, and an adder that adds the signal hold circuit and the luminance signal. Radiation-resistant Color 7 TV camera as described in Section 1. 5. The radiation-resistant color 7 TV camera according to claim 1, characterized in that a white level signal is used in place of the black level signal. 6. A luminance signal level correction circuit is provided with a black level mask at both ends or one end of the target, and a timing circuit that selects the black position, and a subtractor for the difference between the black level mask signal at that time and the unirradiated black level mask signal. Claim 1, characterized in that it is comprised of: a signal hold circuit that holds the output of the subtracter using the output of the timing circuit as a trigger; and an adder that adds the signal hold circuit and the luminance number. The radiation resistant color TV camera described. 7. The radiation resistant device according to claim 1, characterized in that the luminance signal level correction circuit includes a lens deterioration amount correction circuit for correcting the amount of deterioration caused by the lens between the signal hold circuit and the adder. Sex color TV camera.