SU1309056A1 - Device for converting optical signals - Google Patents

Abstract

The invention relates to the field of aESTO-mathematics and computer technology and is intended for reading graphic and symbolic information. A feature of the invention is to improve the accuracy of the device by compensating for the sustained component of the optical signals. The device comprises a photodetector, a signal generation unit, a comparison unit, the first and second peak detectors. 2 Il. co o co o ate Oi

Description

The invention relates to automation and computing, in particular to devices for photoelectric conversion of ontic signals, and can be used, for example, in graphic and symbolic information reading devices.

The aim of the invention is to improve the accuracy of the device by compensating for the constant component of the optical signals.

FIG. 1 shows the scheme of the proposed device; in fig. 2 is a timing diagram explaining his work.

The device contains a photodetector 1, a signal generation unit 2, made in the form of an impedance converter and a preamplifier of signals, a first peak detector 3, a second peak detector 4, a comparison unit 5, made in the form of an operational amplifier in differential switching.

The device works as follows.

The optical signal enters the photoreceiver 1, which is a photosensitive circuit with charge coupling, where it is converted into a sequence of pulse trains whose amplitude is proportional to the change in the image illumination (Fig. 26) projected on the photoreceiver (Fig. 2a), and further, through the signal generation unit 2, is applied to the peak detectors.

Due to the choice of the constant time of the peak detectors, the envelope of the stack is removed from the output of the first detector, corresponding to the change in illumination of the projected image in the read section, and from the output of the second detector from

five

0

five

0

The level corresponding to the background level is measured (Fig. 26).

Further, the envelope signal of the packet and the signal corresponding to the background level are supplied to the inverting and direct input of the comparator unit 5 and subtracted. Thus, at the output of the comparator unit, an output signal is obtained with an amplitude independent of the background level (Fig. 2d), since when the background changes, both the envelope signal of the packet and the constant level applied to the non-inverting input of the comparator unit change.

The accuracy of the optical signal conversion in the proposed device is higher than in the known one, since in this case the amplitude of the converted signal is determined only by the difference in illumination of the background and the read section, since the useful signal (envelope) is compared with the signal determining the background level. the gain (conversion) depends on the level of the constant component of the signal to be converted (background level) and, thus, the amplitude of the signal is determined by the level of the constant component.

Claims (1)

Invention Formula A device for converting optical signals containing a photodetector, the output of which is connected to a signal conditioning unit, and a comparison unit, characterized in that, in order to improve accuracy, it contains first and second peak detectors, whose inputs are connected to the output of the signal conditioning unit, and the outputs connected to the direct and inverting inputs of the comparison unit. 2. / Projected Readable Image Background levels / FIG. 2