SU1695374A1 - Data display device - Google Patents

Abstract

The invention relates to automation and computer technology and can be used in information processing and display systems on gas discharge display panels. The purpose of the invention is to increase the display contrast. This goal is achieved by the fact that the device containing the information input unit 5, the gas-discharge display panel 4, the keys 3, the sweep unit 2, the synchronization unit 1, the switch 8 and the matching elements 7 on the diodes are introduced, which allows reducing the switching delay of the keys and duty cycle of control pulses.

Description

WITH

with

The invention relates to automation and computer technology, in particular, to the technique of information systems, and can be used in the development of information display devices on a gas discharge matrix indicator of direct current.

The aim of the invention is to increase the contrast of the displayed information.

The drawing shows the structural scheme of the claimed device.

The device contains a synchronization unit 1, a scanner unit 2 controlling transistor switches 3, which sequentially connect the voltage of the power source (Ep) to the electrodes of the columns of the gas-discharge indicator panel (GUI) 4. The electrodes of the GUI unit 4 are connected to the outputs of the information input unit 5, the input which is the information input of the device. The electrodes of the columns of the ISU 4 are connected through resistors b to the bias voltage source ECm1. Using the diodes 7, the electrodes of the scanner of the ISU 4 are interconnected or in groups and connected via switch 8 (single-channel or multichannel) to another source of bias ECm2. The multi-channel switch 8 provides alternate connection of the groups of scanning electrodes to the bias voltage source ECm2.

The synchronizer 1 determines the interaction in time of the scanner 2, the information input block 5 and the current switch 8.

The keys 3 and the switch current 8 can be performed on transistors

The device works as follows.

The synchronization unit 1 sets the operation mode of the scanner 2, which,

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keys 3, performs image scanning on the electrodes of the columns of the ISU 4. The image is synthesized sequentially column by column, in accordance with the incoming information through the information input block 5 synchronously with the image scanning.

Depending on the information displayed, each column of the ISU 4 can be excited by one or two or all elements of the information display. In accordance with this, currents of varying amplitude flow through the electrodes of the columns of the ISU 4 and the corresponding switches 3. In real GUI 4 control circuits, switch 3 is selected from the conditions for providing the necessary voltages and currents (usually a transistor operating in a key mode). Switching the transistors from open to closed is accomplished with some delay, due to the accumulation of minority carriers in the base area. As is known, the magnitude of this delay is the greater, the greater the depth of saturation of the transistor switch, which is determined by the ratio of the base and collector currents. Since the collector current varies from zero to the maximum value determined by the current maintaining the discharge of all the display elements of the GUI 4 column, the depth of saturation and, therefore, the turn-off delay of the transistor will vary greatly. These fluctuations in practical circuits reach 5 µs. Such a turn-off delay increases the duty cycle of the control pulses and thereby reduces the brightness and contrast of the displayed information.

The known method of reducing the saturation depth by introducing feedback between the collector and the base is unacceptable for the following reasons. High-voltage transistors used as keys have high saturation voltages (for example, the KT940A transistor has a saturation voltage of up to 10 V), therefore, to reduce the turn-off delay, it is necessary to complicate the base current reference circuits (up to 2-3 additional sets). for each key), which significantly increases hardware costs. In addition, the diodes that can be used in these circuits should have a very small volume charge, since otherwise the switching off front will be very shaky. In some cases, Schottky diodes are used, but they have a small reverse voltage and in this case not applicable.

To reduce the turn-off delay of the transistor switch 3 closed in the base circuit, charge carriers are inserted through the diodes 7 into the collector with the help of a current switch 8, which ensures that the transistor switch 3 is turned off as soon as possible.

The current pulse of the current switch 8 is supplied only to the open transistor switch 3, the moment of the pulse and

0, the duration is determined by synchronizer 1.

This reduces the turn-off delay of the key 3 by compensating for minority carriers in the transistor. but

5, diodes 7 also have a turn-off delay, which leads to a slight increase in the turn-off delay of switch 3 due to the flow of current from the Ep source through the non-switched-on diode 7 and through the open switch 0 and subsequent switch 3. The unification of the ISU scanner electrodes 4 odd allows each group to be connected alternately through a current switch to a voltage source

5 displacement ESm2. With this inclusion, each subsequent diode of the 7th group will have time to restore its conductivity over a period of time equal to the sample period of the column (minimum period of 15 μs), and

0 thereby eliminates the delay for turning off the key 3 due to the inertia of the diode: the moment the current switches 8 are turned on and its duration is determined by the synchronizer 1.

5 An experimental sample of a device made on the basis of an IGG164x64 gas-discharge indicator, using KT850A transistors as key elements, has a transistor turn-off delay of up to 5 μs. Using a current switch and combining through the diodes of all the sweep electrodes reduces the switch-off delay of the key 3 to 1 µs, which is 15 µs for the pulse duration of the sample

5 (at a frame frequency of 1000 Hz) is equivalent to an increase in brightness by about 26% and, accordingly, increases the contrast. Combining electrodes through diodes in two groups reduces the off delay

0 almost to zero, which increases the brightness by about 33%, compared with a device without current switches.

Thus, the introduction of the controlled switch and the connection of the bias voltage source through the diodes 7 to the scanning electrodes of the ISU 4 makes it possible to reduce the duty cycle of the pulses controlling the display of information and thereby increase the image contrast.

Claims (1)

Invention Formula A device for displaying information, containing an information input unit, the output of which is connected to horizontal buses of a gas-discharge display panel, whose vertical buses are connected to the outputs of keys, whose information inputs are connected to one power supply bus, and the control inputs are connected to the outputs of the scanner, input which is connected to the first output of the block, asynchronization, characterized in that, in order to increase the display contrast, a switch is inserted into the device, the control inputs of which are connected to the second output of the synchronization unit, the information input of the switch is connected to another power bus, and the outputs are connected to anodes matching elements on diodes, the cathodes of which are connected-. us with the outputs of the corresponding keys.