SU1401493A1 - Photoselector - Google Patents

Abstract

The invention relates to computing and can be used, Hanpimep, in data processing devices based on display terminals. In order to increase the resolution of the photo selector, an additional differentiating element, a voltage follower, a key and a standby multivibrator are introduced into it, which provides an increase in the resolution of the device due to an increase in its sensitivity to the di (} x) real value of the signal at the output of the photoelectric converter. 2 Il. S

Description

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The invention relates to automation and computing and can be used, for example, in data processing devices based on the display of the xx terminals.

The purpose of the invention is to increase the resolution of the photo selector.

Fig, 1 shows a functional diagram of the photo selector; figure 2 - timing charts of his work.

The photoselector contains a photoelectric converter 1, a generator of 2 horizontal pulses, a key 3, a repeater 4, a amplifier 5, a main 6 and auxiliary 7 differentiating elements, a comparator 8 and a waiting multivibrator 9.

The photoselector works as follows.

The voltage pulses produced by the generator 2 row pulses (Fig. 2a) open the key 3 and charge the capacitance of the photoelectric converter 1 to the supply voltage E. At the same time, the same pulses are used in the control unit of the CRT to scan the electron scanning beam and start the waiting multivibrator 9, the pulses of which block the operation of the gated comparator 8 for the time of the electron beam return and the transient processes of the high-frequency signal, thus excluding the possibility of the passage of spurious signals on output fotoselektora

(Fig.26).

In time intervals between pulses

The generator voltage itself is 2 line pulses The electron beam forms one line of the image on the CRT screen, and the capacitance is discharged by the dark current and photocurrent, and the discharge speed is inversely proportional to the capacitance of the photoelectric converter 1 (including the input circuit capacitance) and directly is proportional to the current flowing through the converter 1 (figv). Thus, the voltage is a certain interval from the change in illumination on the photosensitive surface over time (since the current of the photodiode is composed of a constant dark current and proportional to the illumination of the photocurrent).

increases the linearity of the integral conversion of optical radiation into an electrical signal by eliminating the shunting effect of the input impedance of amplifier 5, and also increases the sensitivity of the photo selector by reducing the mounting capacity of the input circuits. Amplifier 5 provides the necessary gain of the original signal. Differentiating element 6, performed opposite to the integration of a mathematical operation, provides at its output a restored luminous signal, proportional to the change in illumination on the photoelectric converter 1 (FIG. 2d).

If during the scanning of the electron beam across the CRT screen it does not intersect the surface of the photoelectric converter 1 (or intersects the surface, but there is no optical marker), the discharge of the capacitance proceeds linearly and a linearly varying voltage is formed at the input of the voltage follower 4 proportional to the dark current, the intensity of the afterglow of the CRT screen and the magnitude of the background illumination (Fig. 2c, solid line). As a result, at work. In the interval at the output of differentiating element 6, the signal is constant (Figure 2d, solid line). The signal at the output of differentiating element 7 is zero (Figure 2e, solid line) and the signal at the output of comparator B does not appear (Figure 2e, solid line )

If, during the scanning process, the electron beam crosses the photosensitive surface of the photoelectric converter 1 and illuminates the optical marker, an additional photocurrent flows, increasing the rate of voltage change at the input of the voltage follower 4 (fig. 2b, dashed line). After amplification and first differentiation of a solid signal at the output of differentiating element 6, a video pulse appears at the working interval, the amplitude of which is proportional to the brightness of the marker, the temporary position to the position of the marker (converter 1) on the CRT screen, and the duration of the video signal

The pulse is determined by the mutual dimensions of the marker and the photosensitive surface of the photoelectric converter 1 (Fig. 2e, dashed line). This pulse, after filtering out the constant component of differentiating element 7 (to eliminate the effect of afterglow and background illumination), is fed to the input of comparator 8 (fig.2d, dashed line) and generates an information signal at the output of the last (fig.2e, dashed line).

Claims (1)

In this way, the selection of the optical marker by the photo selector circuit is carried out, since the moment of appearance of the leading edge of the information signal at the output of the comparator 8 uniquely determines the coordinate of the photoelectric converter 1 of the photo selector. : Invention Formula A photo selector containing a photoelectric converter, an amplifier and a main differentiating element connected in series, a comparator whose output is an output of the device and a horizontal pulse generator, characterized in that, in order to increase the resolution of the photo selector, it contains a key, a voltage follower, waiting multivibrator and additional differentiating element, the output of which is connected to the information input of the comparator, and the input - to the output of the main differentiating element-} in stroke monostable multivibrator is connected to a strobe input of a comparator and input - with the output of the generator of line pulses and a control input: etyucha yield the photoelectric converter is connected to the input of the voltage follower and to the information input of the key; the output of the voltage follower is connected to the input of the amplifier. (ptJe.l 2  2fc6e / 77aeo (/ / toto) X