DE1762349A1 - Code scanner - Google Patents

Description

Dipl.-Ing. Dipl. Oec. publ. DIETRICH LEWINSKY

PATENT ADVOCATE Munich 21 - Gotlhardstr. 81

Telephone 5617 62

May 31, 1968 5132-Il / Gd

Corapagnie Pran9aise Thomson Houston - Hotchkiss Brandt, Paris 8e, Boulevard Haussmann 173 (France)

'' Code scanner ¹¹ |

French priority of 6 June 1967 from the French patent application 109 305 (Seine)

The invention relates to a code scanner which is fastened either directly or via reduction gears on its axis Discs that carry codes arranged on concentric circular paths, which by means of the discs through illuminated photocells are scanned. Am such a code scanner transmits the measurement of a physical quantity by means of a coded number.

Such devices are used in particular for the numerical control of machine tools, where they are used, for example, to transfer the measured variable of the position of the table of the machine tool into coded information

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which is done directly by an electronic switch are comparable.

There are already code scanners that enable e.s to meet such conditions and a coded disk and have a feeler axis cross for circular paths. This coded disk is made of glass or some

^. other translucent rigid material. She wears several Circular paths made up of translucent areas, each corresponding to a binary digit "1", and opaque areas Regions are formed which each correspond to a binary digit "0". That from a lighting fixture outgoing light is passed through a lens after it has traversed the disk and the axillary concentrated on the photodiodes assigned to the circular paths. These photodiodes process the light signals received in this way, to by means of an electronic circuit a

'to give a binary display of the position of the sensor.

Another type of code scanner uses two sheets of glass, each with several formed on them Include circular paths and clear and opaque areas. These two discs are located on either side of a lamp with a straight filament running over

these disks the Photo-I arranged opposite each lane

diodes illuminated. One of these disks is immediate connected to the mechanical shaft of the code scanner,

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while the other is connected to it via a reduction gear. The currents supplied by the photodiodes must then be processed in an "electronic circuit", which elaborates the coded number which the measurement result of the angular position of the mechanical driving the scanner Wave iste Sin disadvantage of this G-er ate is that they need optical devices to concentrate the light rays. Furthermore, the use of a Disc made of transparent material either loses light through the passage of light or through multiple reflections., a »The too great rigidity of these panes can also be uncomfortable when the scanner is significant Is subject to vibrations. Besides, it can happen that Viurch released that through the glowing white lamp Heat the proper operation of the reading organs is disturbed.

The invention is based on the task of creating a code scanner of the type mentioned at the outset which, while avoiding the liaehteile adhering to the devices described above. it enables the position of a moving part to be controlled to be constantly marked. This object is achieved in the code scanner proposed here in that, according to the invention, several scanner stages are provided, each having at least one .thin metal disk on which the codes are represented by perforations.

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An advantageous embodiment of the invention Code scanner is that the perforation with The circular path carrying the largest dimensions lies at the edge of the disc, so that the perforations are now protruding of the edge of the disc.

In order to increase the robustness of the "disks, it is advantageous if, in the case of scanning stages, the for each circular path have two read cells, the perforations of great length have rigid bridges.

Another advantageous embodiment of the invention According to the code scanner, the rigid bridges are arranged in each switching area of the reading cells are. -

Another advantageous embodiment of the invention according to code scanner is that the guided to the different scanning stages light from a single Light source is guided to the scanning stages via fiber optics.

Another advantageous embodiment of the invention Code scanner consists in that the light source is arranged outside of the scanning stages.

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1762343

A very advantageous embodiment of the invention Code scanner is that the first sampling stage two encoded in a reflexive system and the other scanning stages each encoded in a natural binary system Have discs "

Other features and advantages achieved through them emerge from the description relating to the drawing. In the drawing, for example, selected embodiments of the code scanner according to the invention are illustrated. Show it:

Pig. 1 shows the principle diagram of an embodiment of the invention Code scanner,.

2 shows the simplified diagram of the distribution of the reading cells opposite the tracks of the discs,

Mg. 3 shows the principle diagram of another form of implementation of the code scanner according to the invention,

4 shows one of the disks coded in the reflexive system the first sampling stage and

Fig. 5 shows a disc encoded in the natural binary system the other sampling stages.

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The code scanner according to the invention appears externally in the form of an arrangement of several cylinders 21, 22 and 23, as shown in FIGS. 1 and 3. Each of these cylinders encloses at least one coded disk 31, 32 and 33, read cells 51, 52 and 53 and light guides 41, 4-2 and 43, which distribute the light coming from a lighting device coming from a single light source 7 mounted outside the arrangement is made. The light guides consist, for example, of optical fibers and allow the use of a single light source 7 to achieve a multitude of scanning stages to illuminate, thus avoiding different sources for each stage and avoiding the search for the light source in which an error occurs in the event of a defect. Furthermore, the light source 7 is located outside of the scanner, making it easy to access. If the light source 7 consists of a light bulb, you can use a stronger and therefore more robust filament, because there is no risk of the heat released by the filament spreading to the level of the cells and consequently disturbs reading. Furthermore, optical means for concentrating the rays are avoided.

The coded disks 31, 32 and 33 are either directly with the axis of rotation 1 of the code scanner or permanently connected via reductions 61 and 62. the

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slowest rotating encoded disk 33 makes a maximum of one revolution for the entire displacement of a table of the machine tool when the code scanner is used in such an application. The number of scanning stages, such as 21, 22 and 23, depends on the accuracy The measurement carried out and the total displacement of the table of the machine tool. In the example selected - «- embodiment of the inventive coding ä scanner with three scanning stages, the first scanning stage 21 allows the hundredth and tenth of a millimeter and the millimeter, the second scanning stage 22 the Centimeters and the third scanning stage 23 the decimeters. However, even more scanning stages can be added, if this is technologically possible, and the reading accuracy can be increased by slightly changing the first scanning stage 21.

The drive of the code scanner can be in different, ' Styles according to the desired precision and the The type of machine used can take place, for example starting from an ordinary screw, e.g. the one that one of the translational movements of the table of the machine tool guaranteed to be carried out. It can also be based on a ball-bearing spindle, which is a Backlash reduction enables, or a rack carried out v / ground that of the normal setup of the machine is added. You are in this pail of dimensional changes!

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of the organs of the transmission of motion freed. These changes are essentially squeezing or pulling apart, to which the drive spindle is subjected to.

In Fig. 1 is the principle diagram of an embodiment of the code scanner according to the invention shown. Each sampling stage comprises a purely binary coded disk, The disk 31 of the first scanning stage 21 comprises, for example, 1,000 points and is directly connected to the drive shaft 1 of the Code scanner connected. It makes it possible to measure the hundredths and tenths of a millimeter as well as the millimeter. The disk 32 of the second scanning stage 22 comprises 10 points and is connected to the drive shaft 1 of the code scanner a reduction 61 of 1/10 connected. The disk 33 of the third sampling stage 23 also comprises 10 points, however, rotates ten times slower than the disk 32 due to a second reduction in the ratio 1/10. The reduction 61 can be omitted, the disk 32 can then encompass 100 points and the reduction 62 set with 1/100.

Due to inaccuracies in engraving and also scatter the response time of read cells 51, 52 and 53 actually find the switching operations that are to take place simultaneously take place consecutively. It therefore arise within

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digit readings deviating from the switching ranges. Around To avoid disadvantages, one uses a device to resolve the ambiguity that exists in placing two cells per lane of the disc, like this is shown in! ig »2. The group of cells on the top 531 is not fed normally and reads the information engraved on the disk. At the moment of transition from 9 to 0 of the previous decade, one stops feeding this group of cells and now feeds the one below Cell group 532 “This is how these cells read effectively and simultaneously, even if the engraving of the disc is imperfect the following information «, The return to the supply of the upstream cells 531 takes place when has rotated the previous disk through an angle of 180. This makes it possible to reduce the reading error to the inaccuracies ι the engraving of the path with the lowest absolute weight, i.e. in the example described of the train that has the hundredth! Millimeters for sure.

The disc 31 should have 1,000 points. One encodes they preferably in a reflexive system. Indeed When reading a reflexive code, there is only a single cell that changes state at the same time, while for a -j

natural binary code often multiple cells are provided, which change their state at the same time, whereby a! significant source of error is introduced when the points of

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Discs are very close to each other. The reflexive code makes it possible to avoid the device for resolving the ambiguities.

An advantageous embodiment of the invention Code scanner is shown in Fig. 3. It consists in the disk 31 of the first scanning stage 21 in two disks 311 and 312, which are both coded in the reflexive system, and therefore only one group of reading cells each to need »The engraving of these discs is made easier by the fact that the perforations are larger and fewer are crowded, which also makes it possible to exclude possible reading errors. The light guide 41 v / ird between the two disks are inserted and simultaneously illuminates the two cell groups 511 · and 512, which correspond to the corresponding Disks 311 and 312 belong.

The discs used are made of metal and are very thin. The coded digits are through on them Perforations shown. The latter can for example can be produced by a chemical process. The thinness of the discs enables the reading cells bring them as close as possible to the light guide. On the other hand, the light passes through the perforations without change, whereby it is made possible to use conventional reading cells and a simple electronic utility circuit. Daa weaning

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of dust on these discs will not change the reading, if it is assumed that the coded digits are represented by the perforations _β On the other hand, these discs are robust and same vibrations due to their flexibility of. However, in order to prevent excessive deformations during the rotation of these disks, one increases

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their Stairrheit by arranging / at its edge the encoded circular path having the largest perforations _β These perforations of the disc edge are then formed by recesses. 8

In Figure 4, one of the disks 311 and 312 is the first Scanning stage 21 of the code scanner is shown. One distinguishes six paths coded in a reflexive system "

In Pig. 5 is a slice of the other sampling stages or 23 shown. This slice is in natural binary encoded and comprises ten points.

Certain perforations are significant in length. One increases the "resistance of the disc by" metallic bridges 9 within these perforations provides. The bridges 9 do not lead to a read error in that a device for resolving ambiguous pages is provided. You can also subdivide the perforations if you have one

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wants to get even stronger rigidity · The number of Bridges 9 »which one inside the perforations can arrange, depends on the number of switchings, of the cells that one carries out.

A code scanner has been described above, which is used in particular for the numerical control of machine tools is adapted according to a system of absolute position marking. This code scanner is robust and little sensitive to vibration and the accumulation of dust on the encoded disks it contains. In him common reading cells and simple electronics are used for information processing.

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Claims (7)

17623AS May 31, 1968 5132-II / Sb Compagnie Francaise Thomson Houston - Hotchkiss Brandt, Paris 8e, Boulevard Haussmann 173 (France) Patent claims: 1.) Code scanner with either directly or via reductions attached to its axis disks, which carry codes arranged on concentric circular paths, which are scanned by means of photocells illuminated through the disks, characterized in that a plurality of at least one thin metal disk (31 j 32, 33), on which the codes are represented by perforation, are provided with scanner stages (21, 22, 23). 2. Code scanner according to claim 1, characterized in that the carrying the perforations with the largest dimensions Circular path lies on the edge of the disc, so that the perforations now form recesses (8) of the disc edge. 3. code scanner according to claim 1, characterized in that with scanner stages that have two reading cells for each circular path (531, 532), the perforations of great length rigid - 2 0098 197 1609 have bridges. 4. Code scanner according to claim 3 _S, characterized in that the rigid bridges (9) in each switching area
the reading cells are arranged. 5. Code scanner according to claim 1, characterized in that the guided to the various scanning stages (21, 22, 23) Light from a single light source (7) is guided to the scanning stages via light guides (41, 42, 43). 6. code scanner according to claim 5, characterized in that the light source (7) is arranged outside the scanning stages is. 7. Code scanner according to one of the preceding claims, characterized in that the first scanning stage (21) two encoded in a reflexive system and the other scanning stages (22, 23) each one in a natural binary system
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