JPS6345155B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a television camera testing device for easily testing color shift by imaging a test chart with a color television camera.

Conventional technology and problems Color television cameras are often of the three-tube type for broadcasting stations, and the three-color separation optical system is constructed using a dichroic mirror system or a prism system, and a red (R) image pickup tube, It outputs video signals of each color separated by a green (G) image pickup tube and a blue (B) image pickup tube. In this case, it is desirable that there be no deviation between the video signals of each color component. Therefore, the television camera was evaluated by capturing an image of a test chart, inputting it to a monitor television, and measuring the amount of deviation of the image displayed on the monitor television using a ruler or the like.

However, since the test chart displayed on the monitor TV is used to measure the deviation of the video signal of each color (R, G, B) component using a ruler, etc.
The disadvantages were that the operation was complicated and the evaluation varied depending on the person conducting the test.

OBJECT OF THE INVENTION The object of the present invention is to make it possible to quantitatively measure the deviation of R, G, and B signals of a television camera.

Structure of the Invention The present invention provides an inverting circuit for inverting a video signal of a specific color component, such as a green (G) component, of a television camera that images a test chart, and an inverting circuit for inverting a video signal of a color component other than the specific color component. A black and white monitor television that displays the video signal via the switch and the inverting circuit, a bias circuit that adjustably superimposes a bias voltage on the deflection signal of the image pickup tube of the specific color of the television camera. , a digital meter that displays the voltage input to the bias circuit, a reference voltage generation circuit that generates a reference voltage that shifts the test chart displayed on the black and white television monitor by one scale, and a bias that adjusts the voltage to correct the amount of shift. The present invention is characterized by comprising an adjustment circuit, a changeover switch for switching between the bias adjustment circuit, the reference voltage generation circuit, and the idle contact with respect to the bias circuit.Examples will be described in detail below.

Embodiment of the Invention FIG. 1 is a block diagram of main parts of an embodiment of the invention, in which 1 indicates a photographing lens and a three-color separation optical system;
R, 1G, and 1B are a red camera tube, a green camera tube, and a blue camera tube, respectively. Further, 2 is a deflection circuit, 3 is a synchronization signal generation circuit, 4 is a digital meter, 5 is a reference voltage generation circuit, 6 is a signal correction processing circuit that performs signal processing such as waveform shaping, gamma correction, black level fixing, etc.;
is an encoder that combines R, G, and B signals and converts them into an NTSC signal; 8 is a color monitor TV; 9 is a display control circuit; 10 is a black and white monitor TV; R1 to R
9 is a resistor, VR1 to VR3 are variable resistors, A1 to A
8 is an amplifier, 11 is a video signal inversion circuit, SW1
is a changeover switch, and SW2 and SW3 are switches.

A bias circuit is constituted by resistors R7 to R9, variable resistors VR1 and VR2, and amplifier A5, and a deflection signal applied to the deflection coil of the image pickup tube 1G of a specific color, green (G) in this example, is transmitted through this bias circuit. A bias voltage is superimposed. The variable resistor VR1 is used to adjust the test chart so that it deviates by one scale when the bias voltage is used as a reference voltage, and the variable resistor VR2 is used to correct the deviation of the center of the test chart.
The variable resistor VR3 constitutes a bias adjustment circuit to which a +V voltage is applied and applies the adjusted voltage to the bias circuit via the changeover switch SW1. The changeover switch SW1 has a contact a that switches to the reference voltage generation circuit 5, an idle contact b,
It has a contact c for switching to the bias adjustment circuit. Further, the resistors R1 to R3 are used to determine the display brightness of each color component video signal to be displayed on the monochrome monitor television 10.

When testing a television camera, a deflection signal is applied from the deflection circuit 2 to the deflection coils of each image pickup tube 1R, 1G, 1B in response to a synchronization signal from the synchronization signal generation circuit 3, a test chart is imaged, and the changeover switch SW1 is turned on. is switched to idle contact b, switch SW2,
Turn on one of SW3. That is, the deviation of the R signal and the B signal is measured using the G signal as a reference. When measuring the deviation of the R signal with respect to the G signal, switch SW2 is turned on. The signals from each image pickup tube are waveform-shaped by the signal correction processing circuit 6.
Processing such as gamma correction and black level fixation is performed, and G
The polarity of the signal is inverted by an inverting circuit 11. When the switch SW2 is turned on, the inverted G signal and the non-inverted R signal are displayed on the black and white monitor television 10 via the display control circuit 9, and the displayed image becomes a G and R test chart.

While viewing the test chart displayed on the black and white monitor television 10, the variable resistor VR2 is adjusted to correct the deviation in the center O of the test chart.

Next, switch switch SW1 to contact a,
Reference voltage generation circuit 5 is connected to a bias circuit via buffer amplifier A6.

For example, as shown in FIG. 2, the test chart is divided into 18 equal parts in the vertical direction and 24 equal parts in the horizontal direction. In addition, one scale is further divided into two in the periphery. Therefore, if one scale is 100% in the vertical direction,
It becomes 5.556%. Therefore, the reference voltage from the reference voltage generation circuit 5 is set to 5.556V. This reference voltage is superimposed on the deflection signal of the vertical or horizontal deflection coil of the green image pickup tube 1G via the buffer amplifiers A6 and A5. Set it one division away from the center. At this time, the display on the digital meter 4 becomes 5.556V.

Next, switch SW1 is switched to contact c to connect to the bias adjustment circuit. The bias voltage is adjusted by the variable resistor VR3 constituting this bias adjustment circuit, and the deviation in the displayed test chart is corrected. For example, the variable resistor VR3 is adjusted so that the deviations for each zone, such as deviations within the center circle and deviations within the circle whose diameters are points P1 and P2, are corrected.

On the display screen of the monochrome monitor television 10, as shown in FIG. 3, if the display image of the G signal is a solid line (on the screen, it becomes black due to the polarity reversal of the signal), the display image of the R or B signal is a dotted line ( On the screen, the polarity of the signal is not inverted, so it appears white), so it can be clearly distinguished from the light, so it is very easy to make adjustments to correct the deviation. Also, the adjusted bias voltage in this case is measured by digital meter 4.
The displayed value indicates the percentage of deviation. In other words, as mentioned above, the deviation of one scale is
5.556%, and in that case digital meter 4
If the display is 5.556V and the bias voltage for correcting the deviation is 1V, for example, the deviation is 1%.

Although the embodiments described above are for testing a three-tube color television camera, they can also be applied to testing a two-tube color television camera.

Effects of the Invention As explained above, the present invention corrects the deviation of each color component of a color television camera using a bias adjustment circuit consisting of a variable resistor VR3, etc., and adjusts the bias voltage value required for the correction using a digital meter 4.
Since the amount of deviation can be measured quantitatively by direct reading, there is an advantage that testing of television cameras can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a pattern of an example of a test chart, and FIG. 3 is an explanatory diagram of a deviation in a part of a displayed test chart. 1 is a photographic lens and three-color separation optical system, 1R, 1
G and 1B are a red camera tube, a green camera tube, and a blue camera tube, respectively. Further, 2 is a deflection circuit, 3 is a synchronization signal generation circuit, 4 is a digital meter, 5 is a reference voltage generation circuit, 6 is a signal correction processing circuit that performs signal processing such as waveform shaping, gamma correction, black level fixing, etc., and 7 is R ,
An encoder that combines G and B signals and converts them into an NTSC signal; 8 is a color monitor television; 9 is a display control circuit; 10 is a black and white monitor television; R1 to R9 are resistors; VR1 to VR3 are variable resistors; A1 to A8 are An amplifier, 11 is a video signal inversion circuit, SW1 is a changeover switch, and SW2 and SW3 are switches.

Claims (1)

[Claims] 1. An inversion circuit that inverts a video signal of a specific color component of a television camera that images a test chart, a switch that selects whether or not to display a video signal of a color component other than the specific color component, the switch, and the inversion circuit. A black-and-white monitor television that displays a video signal via a circuit, a bias circuit that adjustably superimposes a bias voltage on the deflection signal of the image pickup tube of the specific color of the television camera, and a digital monitor that displays the voltage input to the bias circuit. a reference voltage generation circuit that generates a reference voltage that shifts the test chart displayed on the black-and-white television monitor by one scale; a bias adjustment circuit that adjusts the voltage to correct the amount of shift;
A television camera testing device comprising: a changeover switch for switching between the bias adjustment circuit, the reference voltage generation circuit, and the idle contact with respect to the bias circuit.