SU697956A1 - Device for checking instability of motion-picture camera exposure - Google Patents

Description

one

This invention relates to a cinematic device, namely, devices for controlling the operation of a movie camera.

A device is known to control the instability of the exposure time, based on the measurement of the opening time of the personnel window with an obturator and containing an optical sensor combined successively with an amplifier-former and an information recording unit. The optical sensor converts the luminous flux reflected from the film into an electrical signal, the duration of which is proportional to the time the shutter opens for the personnel window of the camera 1.

A disadvantage of this device is the inability of frame-by-frame measurement and recording of the exposure time.

The closest in technical essence to the present invention is a device for monitoring the instability of the exposure time of a camera,: an optoelectronic sensor consisting of an illuminator, an optical system of a camera and a photodetector, successively connected with the amplifier driver and measuring unit 2.

The disadvantages of this device are the inability to measure the instability of the exposure time from frame to frame at shooting frequencies of more than 5-8 frames per second, due to the display frequency of the measured magnitude. recording unit-chiTO-OMepoM, the complexity of the recording device (DSP with a storage unit or the use of computers), as well as high demands on the illuminator on the stability of the luminous flux and uniform illumination of the movie camera window.

The purpose of the invention is to improve the accuracy and obtain the possibility of frame-by-frame registration.

The goal is achieved by using an optical quantum generator as the illuminator, and the measuring unit contains a selector, one input of which is connected to a stable frequency generator, the second input is connected to the output of the shaping amplifier and the input of the automation unit, and the outputs of the automation unit and selector are connected to the input the counting unit, the output of which is connected to the registering device through the memory block and the code-voltage converter.

The use of an optical quantum oscillator (AGR) as an illuminator makes it possible to increase the measurement accuracy. The laser beam diameter is about 1 mm; therefore, light pulses with a shortened front length of a fraction of a percent arrive at the photodiode input. The use of a digital pulse width meter with conversion as a video recorder makes it possible to measure the dividing frequency of each pulse with simultaneous recording, for example, on a oscilloscope.

The drawing shows the block diagram of the device for controlling the instability of the exposure time.

The device contains an optoelectronic sensor 1, which forms electrical pulses with a shortened duration of the fronts, proportional to the time of exposure. Sensor 1 consists of an optical quantum generator 2 of the optical system 3 of the camera and photodiode 4. Photodiode 4 is connected in series with the amplifier driver 5 and the measuring unit 6. The measuring unit 6 consists of a series-connected selector 7, a counting frequency generator 8, a counting unit 9, a block 10 of the memory, the code-voltage converter 11 and the recording device 12, the output of the amplifier-maker 5 is connected to the inputs of the selector 7 and the automation unit 13, and the output of the automation unit 13 is connected to the second input even block 9.

The operation of the device is as follows.

The laser beam, the passage through the optical system of the camera 3, is modulated by a shutter and hits the photodiode 4, which converts light pulses into electrical ones.

The amplifier-shaper 5 amplifies the electrical signals of the photodiode 4 and converts them into rectangular pulses with a duration equal to the exposure time of the camera. The output of the 1st pulse of the amplifier-amplifier 5 controls the operation of the selector 7 and the automation unit 13, which forms the pulses Reset, Overwrite and synchronization pulses of the beginning of the measurement in order to eliminate the loss of one pulse.

In the selector 7, the pulses from the stable frequency generator 8 are formed into bursts of pulses, which are then fed to the counting unit 9. The measurement result in the form of a binary code is copied from the counting unit 9 using the Pulse Record to the memory unit 10. The latter is connected to the converter 11 voltage, which forms at the output of the measuring unit 6 an analog signal in the form of levels, This signal is fed to a recording device, for example, a loop oscilloscope on which all the measurement results of the magnitude of instability of exposure time from frame to frame, developed in time, are recorded.

Comparative tests of the proposed device with the known have shown that the accuracy of measurements increases several times and reaches 0.05%.

The recorded information is objective, convenient for subsequent processing and research, objective and allows you to conduct various studies in order to identify patterns in the proceeding process.

Claims (2)

1. OSTZ-3039-75. 2.About the method of checking the stability of the exposure mode filming. Technique of film and television, N 4, 1973 (prototype).