JPH0515576U - Bias light circuit for television cameras - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to automatically switch the bias light amount in response to the switching of the sensitivity of the television camera, and to easily reduce the afterimage without changing the ratio of the bias light amount and the signal level. And In a bias light circuit of a television camera having an image pickup tube whose sensitivity can be switched, target voltage generating means for switching and setting the sensitivity of the image pickup tube, and a number and setting corresponding to each sensitivity for setting the light quantity of the bias light. The bias write amount setting means for the value and the sensitivity / bias light switching means for selecting the corresponding bias write amount setting means in conjunction with the sensitivity switching by the target voltage generating means are provided, and the bias is applied even if the sensitivity is switched. The ratio of light and signal level is kept constant.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to sensitivity switching of a sensitivity switching type image pickup tube and bias light setting at that time.

[0002]

[Prior Art]

 For conventional image pickup tubes without sensitivity switching function, it was sufficient to set the bias light amount once, but for high-sensitivity image pickup tubes capable of sensitivity switching, it was necessary to set the bias light amount each time the sensitivity was changed. FIG. 2 shows a configuration of a bias light setting of a general image pickup tube. 1 is a bias light, 2 is an optical system for adding a bias light to the incident light to the image pickup tube 3 ', an optical system, 4 is a bias light driving amplifier, 5'is a target voltage generating circuit, 6 is image processing The circuit, 7 ', is a bias light setting volume. Conventionally, a general image pickup tube does not have a function of switching the sensitivity and the target voltage is constant, so that it is sufficient to set the bias write amount once with the bias write setting volume 7 '.

[0003]

[Problems to be solved by the device]

 When the above-mentioned conventional technique is applied to a sensitivity-switching type image pickup tube capable of obtaining a high sensitivity of 10 to 100 times or more that of a conventional photoelectric film utilizing the avalanche multiplication effect of amorphous Se, the image pickup tube When the sensitivity was changed, it was necessary to readjust the bias light setting volume 7'as shown in FIG. An object of the present invention is to eliminate these drawbacks, automatically switch the bias write amount in response to sensitivity switching, and easily reduce the afterimage without changing the ratio of the bias write amount and the signal level. .

[0004]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention sets a target voltage generating means for switching and setting the sensitivity of the image pickup tube and a light amount of the bias light in a bias light circuit of a television camera having an image pickup tube capable of changing the sensitivity. A bias light amount setting means of a number and a set value corresponding to each sensitivity and a sensitivity / bias light switching means for selecting the corresponding bias light amount setting means in synchronization with the sensitivity switching by the target voltage generating means are provided. With this configuration, the ratio of bias light to signal level remains constant even if the sensitivity is switched.

[0005]

[Action]

 The operation of the present invention will be described with reference to FIG. When switching the sensitivity of the image pickup tube 3, if the voltage of the target voltage generation circuit 5 is switched by the sensitivity / bias light switch 8, the switch connected to the bias light amount setting volume 7 corresponding to each sensitivity is also linked. The bias light amount also changes accordingly. Here, once each bias light amount setting volume 7 is set to a value corresponding to each sensitivity, even if the sensitivity of the image pickup tube 3 is switched, it is not necessary to readjust the bias light amount properly. And the afterimage can be easily reduced by the bias light 1.

[0006]

【Example】

 An embodiment of the present invention will be described with reference to FIG. In the target voltage generation circuit 5 for applying the target voltage to the image pickup tube 3, the target voltage value generated by the sensitivity / bias light switch 8 is switched, and the bias light amount setting volume 7 corresponding to each sensitivity is also switched in conjunction with it. . Here, the volume 7 is connected to the bias light 1 via the bias light drive amplifier 4 via the changeover switch 8. The light output from the bias light 1 passes through an optical system 2 having optical means for adding the bias light to the input light of the image pickup tube, and is input to the image pickup tube 3. The output of the image pickup tube is supplied to the video processing circuit 6.

In this circuit, when the voltage of the target voltage generation circuit 5 is switched by the changeover switch 8 in order to switch the sensitivity of the image pickup tube 3, the bias light amount setting volume 7 is switched in conjunction, and as a result, the bias is set. The light 1 is also switched to the required set value. Therefore, when switching the sensitivity of the image pickup tube 3, if each bias light setting volume 7 is set to correspond to each sensitivity once, the bias light amount corresponding to the sensitivity to be used can be obtained by simply switching the selector switch 8. You can get it.

The bias write amount setting volume 7 corresponding to each sensitivity is set as follows. With the bias light amount when the sensitivity of the image pickup tube 3 is 1 times as a reference, a value obtained by multiplying the reciprocal multiple of the sensitivity to be set is set as the set value of the bias light amount corresponding to the sensitivity. If such a set value is used, the bias write amount is applied at a constant rate regardless of the sensitivity of the image pickup tube 3, and the afterimage can be reduced in the same manner at all times.

[0009]

[Effect of the device]

 According to the present invention, in a television camera using a sensitivity switching type high-sensitivity image pickup tube, even if the sensitivity of the image pickup tube is changed, the sensitivity / bias can be adjusted without re-adjusting the bias light amount each time. The required bias write amount can be obtained simply by switching with the light selector switch. In addition, the bias light amount is set to a value obtained by multiplying the reciprocal of the sensitivity that is set with the value of the sensitivity of the image pickup tube as a reference, so that even if the sensitivity of the image pickup tube is switched, the bias light amount and the signal level are changed. The ratio of can be constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention.

FIG. 2 is a block diagram showing a conventional example.

[Explanation of symbols]

1: Bias light, 2: Optical system, 3: Imaging tube, 4: Bias light drive amplifier, 5: Target voltage generation circuit, 7: Bias light amount setting volume, 8: Sensitivity /
Bias light selector switch.

Claims (1)

[Scope of utility model registration request] 1. In a bias light circuit of a television camera having an image pickup tube whose sensitivity can be switched, target voltage generating means for switching and setting the sensitivity of the image pickup tube, and a number corresponding to each sensitivity for setting the light quantity of the bias light. And a bias light amount setting means for setting values, and a sensitivity / bias light switching means for selecting the corresponding bias light amount setting means in conjunction with sensitivity switching by the target voltage generating means. Bias light circuit for camera.