SU1578843A1 - Synchronizing pulse shaper - Google Patents

Abstract

The invention relates to television technology and can be used to synchronize measuring instruments. The purpose of the invention is to preserve the temporal ratios of the output pulses when the frequency of the input pulses changes. The synchronization pulse shaper contains an AND 1 element, an OR 2 element, sawtooth voltage generators 3 and 4, a comparator 5 inverter 6, and a voltage source 7. Comparator 5 compares sawtooth voltages from the outputs of the generators 3 and 4. The comparison result will be different for even and odd tv signal fields. As a result, at the output of element 1, pulses are generated only during odd fields. Changing the frequency of the lines in large limits does not disrupt the work of the driver. 2 Il.

Description

1

The invention relates to television technology and can be used to synchronize measuring instruments.

The purpose of the invention is to preserve the temporal ratios of the output pulses when the frequency of the input pulses changes.

FIG. Figure 1 shows the structure of a synchronization pulse former; in fig. 2 - time diagrams of his work.

The synchronization pulse generator contains the element AND 1, the element OR 2, the second generator 3 of the sawtooth voltage, the first generator 4 of the sawtooth voltage, the analog comparator 5, the inverter 6 and the source 7 of the reference voltage.

Shaper pulse synchronization works as follows.

The horizontal sync pulses (Fig. 26) are fed to the control input of the generator 4 of the sawtooth voltage, which generates the sawtooth voltage pulses (see the pulses shown in FIG. 2g by a solid line). Frame and line sync pulses (Fig. 2a, b, respectively) are fed to the inputs of the element OR 2, from the output of which a mixture of sync pulses (Fig. 2c) goes to the control input of the generator 3 sawtooth voltage. Since the common bus generator 3 is connected to the Earth bus through the source 7 of the reference voltage, the sawtooth pulses generated by the generator have a constant stand, determined by the magnitude of the reference voltage (see the pulses shown in Fig. 2d by the dashed line). The interval between the decay of the frame sync pulse and the front of the nearest horizontal sync pulse for the first field is two times smaller than for the second field. Therefore, the sawtooth voltage at the output of generator 4 at the considered time intervals for the first field is greater than the voltage at the output of generator 3, and for the second field less. The resulting saw-tooth stresses are compared with comparator 5, the output of which for the first field is a high level in the time interval under consideration and for the second - a low level (fig 2d). In summary, as can be seen from FIG. 2 d, the pulses at the output of the comparator are not only present in

considered time interval (between the decay of the personnel sync pulse and the front of the nearest horizontal sync pulse), but also during the personnel sync pulse. The selection of this sequence of pulses of the first field is carried out by element I 1, for which frame sync pulses inverted using an inverter 6 (Fig. 2e) are supplied to its first input (in this case, gating for the pulses from the output of the comparator arriving at the second input of the element And 1. As a result, the output element And 1 ,. which is the output of the shaper, we have the impulse of the first field, the front of which coincides with the decay of the frame sync pulse of the first field (Fig. 2g). As follows from FIG. 2g, the condition of the device operability is the equal span of the sawtooth pulses of both generators and the choice of the magnitude of the reference voltage in accordance with the inequality

Uc + - (3 +,

(ABOUT

where Uq is the reference voltage;

And - scope of sawtooth pulses (Fig. 2d); NL - generator power supply voltage0

R

When En 0 and U0 - the inequality K

(1) can be converted to mind

jp (1 - 1),

(2)

where K 7 3 0

The sawtooth pulses generated by the sawtooth generators may be non-linear, since the former remains operable with an exponential pulse shape at the output of the generators.

From the description of the work of the imager, it follows that changing the frequency of the rows does not violate its operation. Indeed, a change in frequency, even if it is accompanied by a change in the span of the sawtooth pulses of both generators in a wide range, will not violate the working condition (2). Thus, the driver can operate at a line frequency different from the broadcast standard.

Claims (1)

Invention Formula A sync pulse generator containing an AND element, characterized in that, in order to maintain the temporal ratios of the output pulses when the frequency of the input pulses is changed, an OR element is inputted, the first input of which is connected to the start input of the input first saw-tooth generator and is the input of horizontal sync pulses , the output of the OR element is connected to the start input of the input of the second sawtooth generator, the output of which is connected by the inverting input of the input analog comparator and whose output is connected to a first input of AND, the output of which is the output of the synchronization pulse generator, the output of the first sawtooth generator is connected to the non-inverting input of the analog comparator, the second input of the OR element is connected to the input of the input inverter and is the input of frame sync pulses, the output of the inverter is connected to the second input of the AND element, the first output of the input the reference voltage source is connected to the common bus of the second sawtooth generator 5, the second output of the voltage source is connected to the common bus of the first sawtooth generator and to the common bus of the synchronization pulse generator. FIG. 2