JPH0134438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flange back adjustment device for a television camera.

An example of the basic configuration of a conventional flange back adjustment device for a television camera is shown in FIG. 1 and will be described. 1
is a collimator that simulates infinity, 1a is the collimator lens, 1b is the light source, 1c is the measurement chart, f _c is the focal length of the collimator lens 1a, and 2
is the television camera to be measured, 2a is the lens of the television camera 2 to be measured, 2b is the image pickup tube that converts incident light into an electrical signal, _fs is the focal length of the lens 2a of the television camera 2, and X is the flange back distance. , 3 is a television monitor.

The adjustment method for the flange back adjustment device configured in this way is to capture the projected image of the measurement chart 1c projected from the collimator 1 with the TV camera 2 to be measured, and adjust it to the best focus while monitoring the video monitor 3. The flange back distance X of the television camera 2 to be measured was adjusted. However, since the resolution of a television camera lens generally shows a broad change with respect to the flange back distance X, there is a drawback that the measurement sensitivity during adjustment deteriorates as shown in FIG. That is, at the best focus position X ₀ on the X axis indicating the flange back distance, the ratio ΔE/ΔX of the change ΔE in the output voltage E of the TV camera 2 to be measured to the distance change ΔX is zero, and the best focus position
Since the measurement accuracy is the worst near X ₀ , there is a drawback that it becomes difficult to detect the best focus position X ₀ . Furthermore, since the best focus was adjusted visually while monitoring the television monitor 3, there were many individual differences, requiring skill and poor work efficiency.

The present invention has been made to solve these drawbacks, and it is possible to clearly display the best focus position of the flange back of a TV camera on a display, thereby improving adjustment accuracy, improving work efficiency, and making it easier even for beginners. The purpose is to be able to adjust with time. In order to achieve this purpose, the present invention installs, for example, two measuring charts optically in front and behind the focal position of the collimator lens, and measures changes in the output E with respect to changes in the flange back position of the television camera to be measured. In addition to increasing ΔE/ΔX near the best focus position to improve measurement accuracy, the focus change component obtained from the video signal of the TV camera under test is converted into a DC voltage and displayed on the display. , will be explained in detail below with reference to the illustrated embodiments.

FIG. 3 is a system diagram showing one embodiment of the flange back adjustment device for a television camera according to the present invention.
In Fig. 3, the same numbers as in Fig. 1 indicate corresponding parts, 1d is a measurement chart installed behind the measurement chart 1c installed at the focal position of the collimator lens 1a, and 1e is the measurement chart installed in front of the measurement chart 1c. This is the measurement chart installed. Here, for example, the distances between the measurement charts 1c, 1d, and 1e are set equally.
Set it to . 4 is two measurement charts 1, front and back, obtained from the video signal of the TV camera 2 to be measured.
A separation circuit that extracts signals corresponding to d and 1e.
For example, 4a is an amplifier, 4b is a bandpass filter, 4c is an analog switch that separates the signals obtained from the two measurement charts 1d and 1e, and 5 is a detection circuit that converts the output of the separation circuit 4 into a DC voltage. For example, 5a and 5b are peak hold circuits for the respective outputs. Reference numeral 6 denotes a display that displays the output of the detection circuit 5, and is, for example, a voltmeter.

Next, the operation of the embodiment shown in FIG. 3 will be explained. The above collimator 1 has two measurement charts 1
d and 1e are optically placed back and forth at predetermined positions (equally spaced l in this case), so the flange back distance The outputs of the television camera 2 to be measured when focused on are shown as c, d, and e in FIG. 4. If the flange back position X of the television camera 2 to be measured is now at the best focus position _X0 , the measurement chart c will have the maximum output, and the outputs of the measurement charts d and e will be lower than c. However, the amount of change ΔE/ΔX in the TV camera 2 output with respect to a minute change in the flange _back position
Measurement chart 1 shows a larger change.
Detecting the best focus using the d and 1e outputs is easier. (ΔE ₁ /ΔX≪ΔE ₂ /ΔX) In other words, rather than detecting the position where the output c obtained from the measurement chart c of the focal position of the collimator lens 1a is maximum, it is possible to obtain the focal position of the collimator lens 1a from the two measurement charts 1d and 1e. It becomes easier to detect the position where the difference between the outputs d and e becomes zero.

Output signals d and e having such characteristics pass through an amplifier 4a and a bandpass filter 4b, and are separated into respective output voltages by an analog switch 4c.
The two signals separated by the analog switch 4c are converted into DC voltage by the detection circuits 5a and 5b, and the display 6 displays the difference voltage according to the change in the flange back position X, so that the flange back of the TV camera 2 to be measured is adjustment becomes easy. In other words, a relatively large difference voltage can be obtained even for a minute change from the best focus position X ₀ , so detection accuracy is improved.

Thus, the basic principle of the present invention is that the measurement charts 1 are optically arranged in front and behind the focal point position.
By using the d and 1e outputs, it is possible to improve the measurement accuracy of the best focus position, and at the same time, it is possible to realize an objective flange back adjustment device that is not affected by individual differences by using the electrical signals obtained thereby. can. In this case, the number and position of measurement charts can be selected depending on the characteristics of the lens and other conditions, and the method of processing and displaying signals obtained from the TV camera 2 to be measured during measurement can be determined depending on the method of the TV camera and other factors. Depending on the conditions, it is also possible to use existing methods other than this embodiment.

Furthermore, the basic principle of the present invention (arranging measurement charts optically in front and behind the focal position) can also be applied to flange back adjustment without using a collimator. Furthermore, in the example,
Although a method of arranging a plurality of measurement charts before and after the focal position has been shown, a case where one measurement chart is arranged at an angle is also included within the scope of the present invention.

As explained above, when the flange back adjustment method of the present invention is used, the adjustment work can be performed objectively using a display, for example, and visual judgment becomes unnecessary. Therefore, no skill is required and adjustments can be made efficiently regardless of individual differences, so the practical effect is extremely large. Further, by combining the flange back adjustment method of the present invention, which can detect the best focus position as an electrical signal, with a predetermined adjustment control mechanism, it becomes possible to automate the flange back adjustment.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a conventional flange back adjustment device for a television camera, Fig. 2 is a characteristic diagram of flange back distance versus output voltage of a television camera when the conventional flange back adjustment device is used, and Fig. 3 is a diagram of the present invention. A system diagram of a flange back adjustment device for a television camera showing an example, 1: collimator, 1d: collimator lens 1a
Measurement chart installed behind the focal position of 1
e: Measurement chart installed in front, 4: Separation circuit, 5: Detection circuit, 6: Display, Figure 4 shows the flange back distance versus output voltage of the television camera when using the flange back adjustment device of the present invention. It is a characteristic diagram.

Claims (1)

[Scope of Claims] 1. At least one measurement chart having images optically located before and after the focal position of the lens, a television camera to be measured that captures an image of each measurement chart, and the measurement chart. A flange back adjustment device for a television camera, comprising a signal processing circuit for extracting each signal component corresponding to each of the measurement chart images from the video signal of the measurement television camera. 2. At least one measurement chart having images optically located before and after the focal position of the lens, a television camera to be measured that captures each measurement chart image, and a video signal of the television camera to be measured. A flange comprising: a signal processing circuit for extracting each signal component corresponding to each of the measurement chart images; and a display for displaying the difference in output signal level of each of the signal processing circuits. Back adjustment device.