SU1760638A1 - Multichannel device for image generation - Google Patents

Abstract

The invention relates to a television technique and can be used to form an image on an LED screen. The essence of the invention is a multichannel imaging device containing n channels 1-1 ... 1-n, each of which consists of a two-input amplifier 2, a resistor 3, an LED 4 and a key 5, as well as a clock generator 6, a regulator 7 brightness and shaper 8 pulse duration. 6-8-1, 7-8, 7-1, 2-3-4. 1 il.

Description

The claimed invention relates to an optoelectronic instrument making device and can be used in LED imaging devices. The known device (U.S. Patent No. 3760181, G0 / t1 / 16, published on 18.09.73) contains a multi-element LED indicator connected to the outputs of a multi-channel amplifier, the first inputs of which are inputs to the device, and the second ones are connected to the image brightness controller . In this device, the brightness of each LED is controlled by the value of the output current of the amplifier channel to which it is connected. The variable component of this current is determined by the signal at the first input, and the constant component is determined by the magnitude of the signal from the image brightness control, common to all amplifier channels. A disadvantage of this device is the banding of the image it creates, caused by the difference in luminance between the individual LEDs. The typical variation in the intensity of radiation between the individual elements of the LED indicator is 15-100% (Electronic equipment. Series Microelectronic devices, 1977 issue 5, p. 7) and in some cases can reach 250-300%.

The closest to the proposed invention to the technical essence and the achieved effect is the device (England patent No. 1451082, H 04 N 1/24, published on 09.29.76), in which each channel contains an LED, the first output of which is connected to one bus power supply, the second output is connected to the collector of the transistor, the base of which is connected to the output of the differential amplifier, and the emitter is connected to the inverting input of the differential amplifier, via a variable resistor connected to a common bus, via a fixed resistor The output of a potentiometer connected between the other power bus and the common bus, the non-inverting inputs of the differential amplifiers are connected to the inputs of the device. Comply1L

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By adjusting the variable resistor and potentiometer in each channel, the same brightness of the LEDs in response to the same electrical signal is provided. The same change in brightness is maintained within the linear dependence of the brightness of the LEDs on the magnitude of the currents flowing through them. However, in the region of small currents, this dependence becomes nonlinear (automation schemes with photosensitive and emitting semiconductor devices. VG Voronin et al. Moscow, Energii, 1972, p. 38) and an additional spread of the radiation characteristics of LEDs appears.

The purpose of the proposed invention is to improve the image quality by increasing the accuracy of the image signal formation.

This goal is achieved by the fact that in a multi-channel imaging device containing n channels, each of which consists of a two-input signal amplifier, the first inputs of which are the information inputs of the multi-channel imaging device, and an intensity controller, the output of which is connected to the second inputs of the two-input signal amplifiers of n channels, are introduced successively but connected clock generator and pulse width former, the control one, whose input is Connected to the output of the luminance regulator, and in each of the n channels there is a resistor connected between the output of the two-input signal amplifier and the LED input and a key connected between the input and output of the LED, while the output of the pulse width former is connected to the control inputs of the keys of each of the channels .

The distinctive features of the proposed invention satisfy the criterion of significant differences, since such a construction of a multi-channel imaging device is not revealed in the known sources of information.

The drawing shows a multi-channel imaging device, where the first inputs of two-input amplifiers 1 are connected to the device inputs, the outputs of LEDs 2 are connected to the power bus IV, the inputs of LEDs 2 are connected via resistors 3 to the outputs of two-input amplifiers 1, parallel to the LEDs 2 switches 4 are included, control inputs the keys 4 are connected to the output of the pulse width imager 5, the first input of which is connected to the clock generator 6, the second input is connected to the brightness controller 7 and the second inputs of two running amplifiers 1.

The device works as follows. In accordance with the signal from the luminance regulator 7, the outputs of two-input amplifiers 1, LEDs 2 and resistors 3 flow constant currents, causing the LEDs 2 to glow the same way. With the frequency of the clock generator 6, the signals opening the keys 4 appear at the output of the clock generator 6 At these times, the keys 4 bypass the LEDs 2 and the output currents.

amplifiers 1 flow through the keys 4 and the LEDs 2 do not emit light. When the keys 4 are opened, the output currents of the amplifiers 1 again flow through the LEDs 2. The observed brightness of the LEDs will be proportional to the ratio of the duration of the current flow through the LEDs to the period T of the pulse. If it is necessary to reduce the brightness of the image being formed using the brightness regulator 7, the signal value at the second inputs of amplifiers 1 simultaneously changes, reducing the value of their output currents and hence the brightness of LEDs 2. Also, using the pulse width generator 5, the duration of the on keys will increase 4 and a reduction in the duration T of the time of flow of currents through the LEDs 2. This will give an additional decrease in the brightness of the observed image. When the signal from the brightness control is reduced by a factor of 10, the output current of the amplifiers 1 decreases by a factor of 10, the turn-on state of the LEDs 2 also decreases by 10

time. Such a decrease in the duration of the on state of the LEDs 2 will give an additional decrease in luminance by 10 times and, accordingly, a joint decrease in the observed luminance of the image in 100

time. This ensures the accuracy of luminance modulation when it is adjusted 100 times. Simultaneously with controlling the brightness of the LEDs 2, the constant signal from the brightness controller 7, the amplifiers 1 change

The brightness of LEDs 2 in accordance with the signals at the inputs of the device.

The frequency of the clock generator 7 should be twice the maximum possible frequency of the signals at the inputs

device so as not to limit the bandwidth of the device. Switching 2 keys 4 in parallel to the LEDs allows simple elements to be used as them. Key resistance 4 in

the closed state must be several orders of magnitude greater than the resistance of the LEDs 2 in the light-emitting state, however, the low resistance of the LEDs in this case makes it possible not to impose high requirements on the resistance of the keys 4 in the closed state. And a sharp break in the current-voltage characteristics of LEDs, as well as any semiconductor diodes, reduces the requirements for the resistance of keys in the open state; a sufficient condition is that the voltage in the open-voltage switch does not exceed the voltage drop in the current-voltage characteristics of the LEDs. As switches, field-effect transistors, bipolar transistors, etc. can be used. The spreading resistors 3 reduce the penetration of the control key pulses 4 through their parasitic capacitances to the output cables and amplifiers 2, forming the integrating chains with the capacitances of the wires and the output capacitances of the amplifiers. Thus, the image quality is improved by introducing a series-connected clock generator and pulse width driver , the control input of which is connected to the output of the luminance regulator, and in each of the channels - a resistor connected between the output of the two-input amplifier signal and the LED input and

a key connected between the input and the output of the LED, while the output of the pulse width former is connected to the control inputs of the keys of each of the channels.

Claims (1)

Multi-channel imaging device comprising n channels, each of which consists of a two-input signal amplifier, the first inputs of which are information inputs of a multi-channel image forming device, and an LED, and a brightness controller, the output of which is connected to the second inputs of two-input signal amplifiers n channels, characterized in that, in order to improve the quality of the image by increasing the accuracy of the formation of the image signal, but the connected clock generator and pulse length former, the control input of which is connected to the output of the brightness controller, and in each of the n channels a resistor connected between the output of the two-input signal amplifier and the input of the LED, and the key connected between the input and output of the LED, the output of the pulse width former is connected to the control inputs of the keys of each channel.