SU436454A1 - DIGITAL TELEVISION PHOTO-ELECTRIC COLORIMETER - Google Patents

Description

one

The invention relates to the field of television.

Digital television photoelectric colorimeters are known, which contain a luminous flux analyzer with a photodetector, an electrical signal amplifier, an AC-to-DC signal converter, an analog-code converter, an arithmetic unit, and an indicator.

However, in known devices, in the process of converting an analog value to a digital code, a discretization error occurs, which affects the accuracy of the operations performed in the arithmetic unit. The discreteness error arises as a result of quantization of a continuous measured value and is due to the finiteness of the number of quantization levels. In this case, the magnitude of the relative conversion error depends on the error of the discreteness and the level of the signal applied to the input of the analog-code converter.

. In order to reduce the relative conversion error in the measurement of color coordinates and improve the accuracy of calculating the chromaticity coordinates in the proposed device, a digital controlled impedance is connected between the input and output of the electrical signal amplifier, and connected in series to the output of the amplifier

the program block, the counter, the decoder and the keys, the control inputs of which are connected to the corresponding decoder outputs, the key outputs are connected to the corresponding digital control resistance inputs, one of the outputs of the program block is connected through the driver to the input of the coincidence circuit, the other input of which is connected through the output of the amplifier, and the output of the coincidence circuit is connected to the drive of the optical filters.

Jrta drawing shows the block diagram of the proposed device.

The proposed colorimeter contains a luminous flux analyzer with a photodetector 1, an amplifier 2 AC, a converter d AC into a constant, a converter 4 analog-code, an arithmetic unit 5, an indicator b, a digital controlled resistance /, keys-W, a decoder 11, the counter 12, the software block 13, the driver 14, the delay block ib, the coincidence circuit iti, the drive device 17. The digital resistance 7 consists respectively of the resistances 18-21.

The colorimeter works as follows. To reduce the effect of the discreteness error on the result of calculating the chromaticity coordinates, it is necessary to set the optimal gain factor of the amplifier 2

for three consecutive signals from the luminous flux analyzer and photodetector. Therefore, before measuring the color coordinates, an adjustment cycle is performed, during which the optimum gain factor is established. To do this, in the initial state, i.e., before the signal is fed to the amplifier 2, the counter 12 is reset, while the keys 8-10 are open and the digital control impedance 7 has the maximum value. Thus, in the initial state, the gain factor of amplifier 2 is set to maximum.

After the conversion of the light flux into an alternating current electrical signal is completed, the signal is amplified and output from amplifier 2 goes to block 13. If (signal amplitude and Yet is the reference voltage) is performed for signal x, then pulse from block 13 goes to the counter 12, which through the decoder 11 controls the resistance value 7. The control is carried out in such a way that the first pulse from the output of block 13 closes the key 8 and the resistance 18, the second pulse - the key 9 and the resistances 18 and 19, the third pulse - the key 10 and resistance 18, 19 and 20.

Simultaneously with a stepwise change in the digital resistance 7, a stepwise decrease in the gain occurs, as long as. Otherwise, the pulse from block 13 is fed to the driver 14, which produces a pulse supplied to the coincidence circuit 16, to the other input of which the pulses come from the output of the delay block 15. In this scheme, a sequence of square pulses is produced, shifted relative to the sequence of signal pulses by time t.

A pulse from the output of the coincidence circuit 16 is fed to a 1-wheel drive device 17 for mounting the next light filter. The use of the former 14 and the delay unit 15 eliminates the possibility of a false triggering of the circuit 16 due to the gentle fronts of the signal pulses. If the luminous flux, passing through the next filter, creates an alternating current signal with such an amplitude that, with a previously set gain, the digital impedance 7 switches to

the next position, and the gain is accordingly reduced as long as. Then the next filter is installed. If the luminous flux passing through this light filter generates an alternating current signal of such amplitude that the condition is not fulfilled with the previously set gain factor, the pulse from unit 13 is fed to the driver, and the next light filter is set.

After setting the optimum gain for three consecutive signals, a measurement is made.

color coordinates, i.e., conversion of the luminous flux into electrical signals of three consecutive signals, measurement of color coordinates, i.e. conversion of the luminous flux into electrical signals, their conversion into a digital code and recording of digital signals into an arithmetic unit. Thus, the result of the recording does not contain; and the relative conversion error that was before the optimal setting

gain factor.

Subject invention

Digital television photoelectric colorimeter containing analyzer

light flux with photodetector and light filter drive, electric signal amplifier, AC signal converter and DC signal, analog-code converter, arithmetic unit and indicator, characterized in that, in order to reduce the relative conversion error in the measurement of color coordinates and improve accuracy calculating chromaticity coordinates, between input and output

an electrical signal amplifier is connected to a digital controlled resistance; serially connected program block, a counter, a decoder and keys are connected to the amplifier output; the control inputs of which are connected to the corresponding outputs of the decoder, the outputs of the keys are connected to the corresponding inputs of the digital controlled resistance, one of the outputs of the software block is connected through the driver with the input of the matching circuit, the other input of which is connected through the delay unit with the output of the amplifier, and the output of the circuit Eni is connected to the drive filters.