DE1098082B - Photoelectric device for scanning the course of a line and converting changes in the direction of the line into electrical signals - Google Patents

Description

GERMAN

The invention relates to a photoelectric device for scanning the course of a Line and conversion of changes in the direction of the line into electrical signals.

Each scanning device, which controls the direction of movement of a tool or other arrangement according to a line in a drawing, usually contains a photoelectric device which generates electrical signals according to the position of the line on the drawing, that is, depending on its direction. These signals are processed further in an electronic device and ultimately act on mechanical devices. For good orientation, a rectangular coordinate system is chosen as a rule, and the results obtained from light-sensitive cells have electrical signals contained in the form of voltage pulses, w hich ^r data on the direction of the line.

There are several electro-optic devices that determine the direction of the line by means of electrical pulses to express. They usually contain besides the optical system (a lens) and a light-sensitive one Cell is a mechanical rotating element that moves a shutter.

The diaphragm must rotate continuously at a constant and relatively high rotational speed, which constitutes a major disadvantage of the known photoelectric devices. To drive the Orifices are used with synchronous motors, motor generators or rotary encoders (selenium connection). These Facilities have bearings that require maintenance, wear out, make noise as well give rise to vibrations due to imprecise dynamic compensation of the rotor, which are undesirable cause additional modulation of the impulse fronts, and which result from bearing friction a very unfavorable variable phase slip in the diaphragm rotation makes noticeable, among other things.

Another device used to generate electrical pulses derived from a line of lines a mirror, which oscillates in a plane and causes the light beam to deflect in such a way that it oscillates in a straight line within the zone of the line. The entire optical system rotates here with the swinging mirror in the direction of the line. If the direction of the line changes, it must change rotate the optical system in the plane of oscillation. So here, too, bearings are required that match those above have mentioned disadvantages and require a complicated structure. They also need moving contacts are used, taking into account the sensitivity of the electronic device, its susceptibility to failure substantially "increase.

The present invention overcomes these shortcomings

Photoelectric device

for scanning the course

a line and transformation

of changes in the direction of the line

into electrical signals

Applicant:

Vyskumny ustav pre niechanizaciu

a automatizaciu,

Nove Mesto nad Vahom

(Czechoslovakia)

Representative: Dipl.-Ing. A. Spreer, patent attorney,
Göttingen, Groner Str. 37

Claimed priority:
Czechoslovakia from November 29, 1957

Ladislav Benes, Nove Mesto nad Vähom

(Czechoslovakia),
has been named as the inventor

the end. It consists in the fact that between the lens and the light-sensitive cell, in front of which a diaphragm is fixed with opening is provided, a tumbling motion along an imaginary obtuse-angled conical surface The level mirror to be brought is switched on, which corresponds to the image falling on the light cell Given point of the line a circular motion.

In such a device rotatable parts are avoided in bearings, so that frictional resistance are switched off and fixed connections between the optical system and the electronic device .can be provided.

To generate the circular movement, the mirror can advantageously be placed in the middle of a pot

109 507/390

magnets with a cylindrical pole attachment and a den Pot covering and the pole approach with space surrounding the pole ring at a small distance from Pole ring spanning membrane be attached, the cylindrical Polaniatz at the end by radial Grooves are divided into four "quadrants, each provided with a voice coil, each of which is opposite Coil pairs are connected in opposite directions and one of these Sptileri pairs is connected to a sinusoidal voltage, the second is connected to a cosine voltage. s-

An exemplary embodiment of the device according to the invention is shown in the drawings. It shows

Fig. 1 is a schematic compilation of the entire device and

Fig. 2 is an axonometric picture of the oscillator for the mirror.

In Fig. 1, a line 2 is shown on a drawing 1. A small area of this drawing, which is delimited by a small circle 3, is projected through an objective 4 onto a diaphragm 5, on which the image 6 of the line 2 is focused. The screen 5 has a small opening 7 and forms part of a base 13. Inside the base there is a light-sensitive cell on which the light passing through the opening 7 is incident. The light-sensitive cell has current terminals 14 and 15. The image is projected through the lens 4 onto the diaphragm 5 via a circular plane mirror 16. The mirror is attached to a membrane Vf of a special electrodynamic system 18 which gives the mirror such vibrations that the mirror plane moves on a conical surface, and thus each point of the line 2 projected in image 6 describes a small circle 19, as is the case for a point in FIG. 1 is shown. During the circular movement of the image 6, a larger amount of light penetrates through the opening 7 for a certain part of a revolution, which corresponds to the light image part of the drawing and for the remaining part of the revolution a smaller amount of light, which corresponds to the dark part projected in image 6 Line 2 corresponds. The light beam modulated in this way falls on the light-sensitive cell, not shown in FIG. 1, and is converted into electrical pulses with the aid of an electronic device connected to terminals 14 and 15, not shown in FIG. These pulses correspond exactly to the modulated luminous flux which passes through the opening 7 and which strikes the light-sensitive cell and the front of each pulse thus corresponds to the moment of the transition of the edge of the line through the opening 7.

If the direction of line 2 changes, sooner or later the line edge will transition through the opening 7 of the diaphragm 5 with constant rotation of the image 6. The voltage pulses thus contain Information about the direction of the line in form, a phase modulation of the front part of the impulses. The mirror only vibrates with a small amplitude. The electrodynamic system 18 is that of a loudspeaker similar. An arrangement which enables a conical oscillating movement of the mirror 16 is shown in FIG.

From Fig. 2 it can be seen that the electrodynamic system comprises a permanent cylindrical magnet 20 and a cylindrical and an annular pole extension 21 and 22, respectively, between which there is a small annular gap for the vibrating coils. The cylindrical pole extension 21 is at the end with two mutually perpendicular radial grooves 23 and 24 which form the end of the Divide the pole approach into four quadrants 25, 26, 27 and 28. Four voice coils 29, 30, 31 and 32 are movably pushed onto these, which are fixed to one another glued and provided on a membrane 33, which by means of a ring 34 at a small distance above of the annular pole extension 22 is attached. In the middle of the membrane 33, the mirror 16 is on the outside intended.

The voice coils located in two opposite quadrants are in theirs with each other magnetic action switched in opposite directions, so that when current passes the coils of the opposite Coil pair in the magnetic field of the gap between the pole approaches an opposite one Get a rash. If, for example, the spool 29 is adjusted upwards, the spool 31 in the opposite is simultaneously Quadrant shifted below. One pair of coils is connected to a sinusoidal voltage, the second to a cosine voltage of the same frequency is connected, so that the resulting mirror movement the Describes the outer surface of a cone. The mirror oscillates with a small amplitude and does not have any rotating components so that it does not require maintenance, does not wear out and the exact phase modulation the impulse fronts are not affected. It also shows that it is very easy to carry out compared to known arrangements and a considerably lower electrical energy consumption. A A major advantage of the device according to the invention is the possibility of low energy consumption easy to increase the number of oscillations of the excitation current and thereby the speed almost arbitrarily the rotation to increase the image of the line on the aperture, which is what known systems with rotating Aperture is extremely difficult. The increased number of vibrations allows for a given accuracy of the scan to increase the speed of the scan of the line, or at a given speed to increase the accuracy of the scan.

Claims (2)

Patent claims: 1. Photoelectric \ ^r orrichtung for scanning the course of a line and conversion of changes in direction of the line into electric signals, at which point by point the batch to be tracked line is projected by an optical system onto a photosensitive cell using a deflecting mirror, characterized characterized in that between the lens (4) and the light-sensitive cell (13, 14, 15), in front of which a diaphragm (5) with opening (7) is fixed, a plane mirror to be brought into tumbling motion along an imaginary obtuse-angled conical surface (16) is switched on, which gives the image of a point on the line falling on the light cell a circular movement. 2. Photoelectric device according to claim 1, characterized in that the mirror (16) in the center of a pot magnet with a cylindrical pole attachment (21) and one covering the pot as well as the pole ring (22) surrounding the pole attachment with space in between at a small distance from the pole ring spanning membrane (33) is attached and that the cylindrical pole attachment (21) at the end through radial grooves (23, 24) in four quadrants (25, 26, 27, 28), each with a voice coil (29, 30, 31, 32) are provided, of which the opposite pairs of coils are connected in opposite directions and one of these coil pairs to a sine voltage, the second to a cosine voltage. Considered publications:
British Patent No. 759,868;
Blackett and Williams essay: An Automatic Curve Follower for Use with the Differential Analyzer, published in 1939 in Proc. Cambr., Phil. «, Soc. 35, pp. 498 and 499. For this purpose one sheet of drawings