FR2487552A1 - - Google Patents

Abstract

THE APPARATUS ACCORDING TO THE INVENTION INTENDED TO READ INFORMATION ON CODED TRACKS, INCLUDES AT LEAST ONE READING HEAD WITH A RELATIVE MOVEMENT WITH RESPECT TO A MAGNETIC OR OPTICAL TRACK. TRACK 10, OR AT LEAST ONE TRACK IF THERE ARE MORE THAN THERE, CONTAINS ADDITIONAL INFORMATION AND THE READING HEAD 13 CONTAINS AT LEAST ONE ADDITIONAL READING DEVICE 16, 16 WHICH READS ADDITIONAL INFORMATION DURING THE RECEPTION OF SIGNALS DEPENDING ON THE LINEAR OR ANGULAR POSITION OF THE TRACK.

Description

The present invention relates to a reading apparatus

  of information which is recorded in binary coded form in at least one information track, with at least one read head which, by means of a reading device, produces pulses under the effect of a movement.

  relative angular or linear in the longi-

  tudinal of the track between the read head and the track,

  and to which an evaluation device is connected.

  Reading devices of this kind which are already known and which are used for digital position measurements determine the position on the basis of an incremental measurement or on the basis of an absolute measurement. The equipment required for an incremental measurement is reduced, because a

  one track is enough and with only two playback devices

  ture, it is possible to determine, in addition to a movement, the direction of this movement. However, this has the significant drawback that, before powering up, after a power cut or other, the read head must be brought

  in a precisely defined position, starting from the-

  which measurement can be performed. Furthermore, without this

  placed in a known position beforehand, it is not pos-

  can check during operation whether a reading

  correct position is performed. Devices that perform

  kill an absolute measure does not have these disadvantages.

  But they usually impose a number of relative leads-

  large and an even greater number of reading devices. They are therefore expensive. In addition, in many cases, space is not available for such a bulky system. They also have the disadvantage that a binary code is generally not usable because it always leads to faults when signal transitions must occur simultaneously in several tracks, these transitions do not occur simultaneously due

2 2487552

  inevitable inaccuracies. It is therefore necessary to operate with a code with a single transition at the time which, for a series

  continuous number of positions, requires a deco circuit

additional age.

  The object of the invention is therefore to propose an apparatus for

  reading the type mentioned in the preamble, the realization

  As simple as that of a known device carrying out an incremental measurement, while being able to perform an absolute measurement. This is achieved by the fact that the track, or at least one track if there are two or more, contains additional information and that the read head has at least one additional reading device.

  who receives the additional information during reception

  tion of signals depending on the linear or angular position

laire.

  Since using the additional information

  one or more absolute positions can be

  characterized, the apparatus according to the invention makes it possible to perform

  kill an absolute position measurement when a single track

  exist. Since it is sufficient for the read head to

  - carries only one additional reading device, the material

  additional riel required is minimized. he

  is even more reduced compared to the material required

  in known devices for absolute measurement in

  which are foreseen two or more tracks and a respectively higher number of reading devices because for the same yield, the invention implements only one

  essentially lower number of tracks and layout

reading tifs.

  A particular advantage is that

  additional information does not allow alone-

  ment to solve the problem of position measurement ab-

  solue. On the contrary, this additional information may

  can be used for other purposes. For example, they allow in a store with shelves, to determine so

  simple the correct aisle or a given level.

  Possible uses for the device according to the invention include, for example, angl encoders, rotation transducers, coded markers as well as positioning devices for elevators, conveyors, shelving installations, etc. Preferably, the additional information is recorded in the track in the form of at least one word in binary code, and the evaluation device combines the pulses produced by the additional reading device with the pulses which depend on the movement.

  linear or angular, and compose them in one word in bi-

  nary, because for this purpose the necessary material is particular

  significantly reduced compared to its yield. This also applies when additional information

  represent at least one absolute position value.

  According to one embodiment, each value of posi-

  absolute tion is recorded in the track, in the form of a sequence readable in series of markings, the beginning of which

  and the end are each specified by a synchronization signal.

  station. To determine an absolute position value, i]

  the read head and the track must move enough

  relatively to each other until: the synchronization signal, or one of the synchronization signals, is recognized. During the following relative movement, the value

  absolute corresponding is read and evaluated.

  In principle, any step can be chosen for the pulses depending on a linear or angular movement. But preferably, these pulses form a sequence of constant steps, because in this case, the intervals of the counting or positioning steps to be measured are the same.

  According to one embodiment, the values of posi-

  absolute tion which form an increasing or decreasing series

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  te by steps of the same height, are recorded in a

  first track, in sectors of the same length follow

  immediately promoting each other. Each of the sectors

  of the same length of a second track, associated with a sec-

  same length of the first track, is divided into equal steps, the number of which is equal to the difference between

  the values of two consecutive positions, or a frac-

  integer, or an integer multiple of this number. The front-

  The special feature of this arrangement is that it only takes two tracks to record a very large number of absolute position values, and thus obtain very high resolution even with long lengths.

path.

  In addition, the reading apparatus according to the invention

  tion is considerably more universal than devices

  known in the sense that the track in which are recorded

  very additional information can be separated spatially from the track in which are recorded

counting information.

  A particularly high yield of dipposi-

  tif of evaluation can be obtained when it is constituted

by a microprocessor.

  Other features and advantages of the

  vention will appear during the description which goes

  follow and on the attached drawings by way of example null-

  ment limiting and on which Figure 1 is a schematic representation of a first embodiment, with an associated simplified diagram, Figure 2 is a schematic representation of a second embodiment with an associated simplified diagram, Figure 3 e .st a time diagram of a pulse train corresponding to the embodiment of Figure 2, Figure 4 is a schematic representation of a third embodiment, Figure 5 is a schematic representation of a fourth embodiment of embodiment with the associated simplified diagram, FIG. 6 is a schematic representation of a fifth embodiment, FIG. 7 is a simplified diagram of the embodiment of FIG. 6,

  Figure 8 is a simplified diagram of a modification

  cation of the embodiment of Figure 6 and Figure 9 is a simplified diagram of a variant

  of the embodiment of Figure 8.

  The embodiment shown in FIG. 1 comprises a single track 10 which comprises sectors of the same length, immediately following one another, and each of which contains a clear zone II transparent to light and a dark zone 12 opaque to light. A

  same length of all sectors is however not ab-

  absolutely necessary. It is nevertheless advantageous because it makes it possible to keep the same dimension for all the counting or position steps to be measured. As shown in Figure 1, a light area Il and a dark area 12

  follow each other along the length of runway 10.

  The lengths of the light and dark areas inside

  each of the sectors of runway 10 can differ

to relate to one another.

  It is thus possible to record information

  in addition to counting or position steps. In one embodiment, the additional information is recorded in track 10 in the form of binary code, that is to say that each sector contains, depending on whether its light area It is longer or shorter than its dark area 12 , binary information in the form of a "1" or on the form of a "0". The signal "1" is therefore recorded

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  in the respective sector when its light zone is longer than the dark zone 12. Conversely, a distribution into a dark zone 12 longer and a light zone 11 more

  short corresponds to a signal "'0". It would obviously be pos-

  It is also possible to use not only the condition that one zone of each sector of the track is longer or shorter than the other zone.; to memorize information, but also the magnitude ratio between two zones, which could be

  for example according to information 1: 4, or 1: 2, or 1: 1.

  The information recorded in track 10 is evaluated using a read head 13, a relative movement in the longitudinal direction of

  the track being possible between this track 10 and the head 13.

  For example, the read head 13 moves along the track 10, in one direction or the other. The read head 13 contains three reading devices which, since in the present embodiment the track 10 consists of an optical reading track, each comprises a transmitter

  light 14, or 15, or 16, and each a light receiver

  track 14 ', or 15', or 16 'Track 10 is between the transmitters and the receivers so that the latter

  change the state of their signals when the light beam

  neux is established between the transmitter and the receiver, and released or interrupted by a dark area. In the present embodiment, the light receiver produces the signal "1" when a clear zone It is located between it and the corresponding transmitter. The two reading devices arranged at

  a relatively short distance from each other in the di-

  rection of the movement of the read head 13, with the transmitters 14 and 15, serve to produce the counting pulses, on the basis of which the counting or position steps are determined, as well as to determine the direction of the

  movement. The third reading device which is con-

  set up by the light emitter 16 and the light receiver

  16 ', has the function of reading the additional information

  recorded in the track. It therefore makes it possible to

  terminate if, in the sector being read, the light area is longer than the dark area 12, and by

  therefore a signal "1" is recorded, or if the area is

  bre 12 is longer and therefore a signal

  "" is saved. The distance between the

  reading device 16, 16 'and the reading device 14, 14' in the direction of movement of the read head is therefore approximately equal to half the length of a

runway 10 sector.

  The light receiver output 14 'is con-

  connected to two monostable scales 17 and 18, which, at the transition of the signal from "" to "1" or from "1"

  at "" at their entry D, deliver an impulse to their exit

  tie Q. The output signal of circuit 17 has the effect of advancing the counter 19 connected to the two circuits 17 and 18 while the output signal of circuit 18 has the effect of making it regress. Since the erasing inputs of the two circuits 17 and 18 are connected to the output * of the light receiver 15 ', when the latter emits a signal e0 ", the Q output of the circuits 17 and 18 does not deliver any signal even if a signal is present at their inputs.

  The light receiver 16 'is connected to a

  entry D of a register 20 controlled by transition. Its other input C is connected to the output of a gate 21, the two inputs of which are connected to the outputs of the circuits

  17 and 18. The register 20 thus stores Vlin-

  instant formation of the 16 'light receiver

  from when a counting or counting operation

  counting takes place. A criterion for accepting information

  of the light receiver 16 'is therefore a transition from the sig-

  nal to the light receiver 14 ', simultaneously with a signal "1" from the light receiver 15'. A register 22, the two inputs of which are connected respectively to the outputs of circuit 17 and of circuit

  18 memorizes whether the information being

  recorded in register 20, were acquired by a movement

  lie forward or backward movement of the head

  13. If we assume for example that the device

  tif de lecture 14, 14 'is just still in the region of a dark zone 12, as shown in FIG. 1, under the effect of a movement of the read head 13 to the right, seen in FIG. 1, the light receiver 14 'delivers a counting pulse, when passing over the light area 11 which follows. At the same time, the signal "1" present at the output of the light receiver 16 'is stored in the register 20. If the read head 13 is

  moves further to the right, no comp pulse

  tage is produced when the reading device 14, 14 'passes over the next dark area 12, because the reading device 15, 15' is in this dark area and therefore the emission of a pulse is inhibited both at the output of circuit 17 and at that

  of circuit 18. As soon as the reading device

  ture 14, 14 'reaches the next clear zone II at the start

  from the next sector of runway 10, a counting pulse

  ge is again produced and a signal "1 'is stored in register 20 because, also in this sector of track 10, the light area 11 is longer than the dark area 12. According to the present example, in the two following sectors of runway 10, the dark area 12 is longer than the bright area 11. Therefore, when the head of

  reading 13 reaches these sectors, a signal "0" is memorized

  se in register 20. For example, the position ab-

  solute of the read head 13 can be determined from

  drawing of the sequence of signals recorded in register 20.

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  The embodiment shown in Figure 2 differs from that of Figure 1 only in that the

  register 20 is replaced by a bidirec- shift register

  23 in diagram of which are connected, as shown in Figure 2, a door 23 'and a register 24. The elements

  correspondents are designated by the same reference numbers

  that in Figure 1, and as far as they are concerned, there

  please refer to the corresponding description of

  the exemplary embodiment according to this Figure.

  Thanks to the use of the shift register, 23, after a predetermined number of counting pulses, therefore of pulses by which the counter 19 has been controlled, coded information is available which, in the present embodiment, is memorized in parallel and can be read. For this purpose, it is appropriate that part of the positions of

  shift register memory, for example the two pre-

  better positions, or reserved to memorize a signal

  code or synchronization signal by means of which the

  goal of a series of associated signals, i.e. a word,

  is identified the presence of syn-

  timing can be identified by means of gate 23 'connected to the code signal outputs of the shift register 23 - When this information is identified, gate 23' sends a reception signal to memory 24 so that the other information which residing in the shift register 23 are received in the correct position in the memory 24. They are then available there at any time for the evaluation. Figure 3 shows an example of a

  series of associated signals, or pulse train, which

  begins with a code signal and ends with the consecutive code signal. In this example, the code signal consists of two consecutive "1" signals and two signals

  "0" following them. The following signals are separated each

  each other by a signal "0", so that two signals "1" never follow each other except for code or synchronization information. Depending on how the

  track 10 is coded, the signal between two sig-

  nals "0" can consist of a signal "1" or a signal "0"

  which is represented by the dotted line. The lon-

  the pulse train is determined by the information that must be stored inside a train,

  for example depending on the importance of the value of po-

  absolute location with which the runway sector is associated,

  corresponding to the pulse train.

  As shown in the embodiment shown in Figure 4, a track 110 which contains, like the track in the embodiment of Figures 1 to 3, additional information in addition to the counting or position step information and which is performed as the track 10 of this embodiment, can be associated with a head

  reading 113 which includes more than one reading device

  ture to read this additional information. Fig. 4 - represents the read head 113 with reading devices 116, 116 'and 124, 124' of them. It is thus possible

  transmit three states to the connected evaluation device.

  different signals per counting step, namely the sig-

  nal "O" at the outputs of the two light receivers 116 ′ and

  124 ', the signal "1" at the outputs of the two light receivers

  miere, as well as a signal "0" and a signal "1" to one or

  the other light receiver. Compared to the mode of realization

  sation of Figures 1 to 3, the three additional signal states

  can be used to form code or synchronization signals, so to identify

  the start or end of a pulse train.

  Figure 5 illustrates an embodiment with

  two parallel tracks. 210 and 210 '. Thanks to one or more

  In several additional tracks, the information recording capacity is increased to a large extent, as is possible in known devices performing absolute position measurement. But with one or more additional tracks, the necessary equipment is by far

  lower than that of these known systems, because a transmitted-

  Serial information is scheduled from pis-

  your individual. The read head 213 which can be animated

  with relative movement with respect to tracks 210 and 210 'in the longitudinal direction of these tracks, includes for track 210 in which the additional information

  are recorded, at least one reading device, pre-

  several ference, each including a light emitter

  216 and a light receiver 216 '.- For identification

  forward-reverse gear is possible, two dis-

  reading positives each including a light emitter

  214 or 215 and a 214 'or 215' light receiver are as-

  associated with runway 210 which, in the form of a track

  tage, has light areas 211 and dark areas 212 of the same length, alternately following each other, which are chosen shorter as shown in Figure 5, which is particularly advantageous when

  the two tracks are planned on separate physical elements.

  and movable relative to each other, and when one

  exact alignment of these elements is not always guaranteed.

  In addition to the reception criterion used in the

  realization described above, it is possible in the pre-

  feels an embodiment of having recourse, as a characteristic

  tick for evaluating the signals of runway 210, at a distance of a defined number of steps from runway 210 '. Track 210 is made up of sectors of the same defined value, the lengths of which each correspond to a defined number of

track 210 'counting.

  The output of a light receiver 216 ′ from the read head 213 is connected to two monostable flip-flops 217, 218, controlled by transition. The output of the second of these circuits is connected to the reset input of a counter 219 which counts the pulses of

  counting produced by two reading devices, consisting of

  each killed by a light emitter 214, 215, and a re-

  light sensor 214 ', 215e, in the manner already described with reference to the embodiments of Figures 1 to 4' La

  output of circuit 217 is connected to the

  clock input of a shift register 225, the input of which is connected to the output of the counter 219. A signal "1" is always introduced into the shift register 225 when the bright area 211 of track 210 is greater to half the number of counting steps that a length of track 210 'contains equal to one of the sectors of the same length of track 210. If the light area 211 of track 210 is

  equal to or less than half the counting steps, a sig-

  nal "0" is entered in the shift register 205. Good

  of course, an extension would be possible in this regard, using

  reading for the evaluation of other numbers of steps, for example-

  ple 1/4 or 3/4 of the number of counting steps associated with

a sector of runway 210.

  It is also obviously possible to effect

  kill a different signal processing in the case of

  placement of the read head 213 forwards and backwards. For example, comparing the lengths of the light or dark areas of runway 210 with the

  no counting of track 210 'is particularly advantageous

  tagger when the two tracks are planned on elements

  movable relative to each other, for example shelving, and a storage vehicle, and that there is

  no exact coordination of a track, for example due

  sound of a spinning of the wheels of the storage vehicle during its movement along the shelving, and the other

  track. Thus, given that at each start of a zone con-

  consecutive, counter 219 is reset to zero, errors

  resulting from inaccuracies in the tracks or their arrangement

  reciprocal actions are not tabulated. If the two tracks 210 and 210 ′ are arranged on physically separate elements, the read head is therefore separated

13 2487552

  corresponding. Figures 6 and 7 show another embodiment with two parallel tracks 310, 310 '. Among these two tracks, which even as in the embodiments already described are with optical reading, and therefore comprise light areas and dark areas, the coding track 310

  contains additional information. The hor track

  box 310 'has light areas 211 and dark areas 312 of the same length, which alternate. A read head 313 comprises for the coding track 310 a reading device constituted by a light emitter

  316 and a light receiver 316 'and, for the hor-

  box 310 ', two reading devices each consisting of a light emitter 314, 315 and a light receiver

  314 ', 315' which are arranged in the same way as the dis-

  positive reading of the counting or position steps of the embodiments already described and which also identify

the counting direction.

  For the production of a code signal or a mark

  synchronization cue, identifying the start of a train

  associated pulses of coding track 310, the possibility

  bility also exists, by counting several transitions, which allows the clock track 310 ', to choose a determined transition as a reference point. If by

  example, fully determined information is detected

  ted by the light receiver 316 ', on the coding track 310, on the dark / light transition in forward or on

  the light / dark transition in reverse as the reception

  light sensor 74 'detects, this can serve as 3D marking of the start or end of the next pulse train. For the reception of the different elements of this pulse train,

* we can then use as criterion, both a transi-

  tion that the retreat of a certain number of counting steps with respect to the appearance of the start or end marking,

therefore of the synchronization signal.

  In the embodiment of Figures 6 and 7, the clock track is arranged so that a count of four transitions is performed. Each sector of the coding track 310, the length of which is equal to that of eight zones of the clock track forming a pulse train, is divided into sixteen successive bit positions,

  to each of which is associated a transition of the pis-

  clock clock. With the exception of the first bit position

  which is associated with the first transition of the train of im-

  corresponding pulses and which is used for the synchronization signal, as well as with the exception of the fifth, ninth and thirteenth bit positions, which must remain free since inside each pulse train a transition corresponding to a first transition

  is identified four times, the other twelve positions bi-

  may be assigned to specific values.

  In the present embodiment, these are the values 2 to 2. Of course, it is possible to choose other values or to save the information under another

form. In the present embodiment, the first train of pulses

  shown on the left contains a "1" in the bit positions to which the values are assigned

  and 210. This train of pulses, and therefore the sec-

  encoder track 310 which contains this train of im

  impulses therefore has the value of absolute position 29 + 2 10 1536; The intermediate pulse train contains a "1 'in the binary positions to which the

4 9 10

  values 2, 2 and 2. The corresponding sector of the runway

  coding code 310 is therefore assigned to the position value ab-

  solue 1552- Likewise, as shown in Figure 6, the absolute position value of the sector of coding track 310 represented on the right is 1568. The difference in absolute position value between each pulse train and the next is therefore 16. Since during the movement of the read head 313 along the sector associated with a pulse train, consequently from the start of a pulse train to the start of the next, sixteen determined by

  the clock track is crossed, these steps can, depending on

  tion of the direction of movement, being added to or subtracted from the position value of the pulse train, so that each step is also defined by an absolute value, which means that the resolving power will

until no individual.

  As shown in Figure 7, the output signals from the light receivers 314 'and 315' are applied to a transition evaluation circuit 330 which, in a manner known for counting four transitions, delivers to its two outputs AI and A2, at each step, therefore for each transition, a counting or counting pulse according to the direction of movement of the read head 316 and which, from

  the known manner for counting a transition, does not

  - delivers an impulse to its A3 and A4 outputs only when a transition is identified by the number 1. The impulses

  counters at outputs Ai and A2 control a counter-

  down-counter 319 and additionally pass in a bidirectional shift register the signals which are delivered by the light receiver 316 'associated with the coding track 310. Since for the transition nO 1 there is only information synchronization and no value position of the pulse train, gate 332, both of which

  inputs are connected to outputs A3 and A4 of the evacuation circuit

  transition transition 330 prohibits an offset operation in the shift register 331. To this end, the output of the gate 332 is connected to the blocking input of the register

  shifted. When the identification of the transfer number

  sition, a synchronization signal is also identified in the coding track 310, the counter 319 is placed in a starting position by the gate 333 for counting,

  and in a final position by door 334 for a decompression

  floor. One of the entrances to the two doors is connected to the

  signal line from the light receiver 316'-

  The other input is connected to output A3 or to output Ah

  of the transition evaluation circuit 330, as shown in

  Fig. 7. The output of gate 333 is connected to that of the inputs of counter 319 by which all the outputs are reset to "0". In a similar way, the exit from the door

  334 is linked to that of the counter inputs 319 by the-

  which all outputs are set to "1". Under the effect of the decreasing transitions of the signals of these doors, two switching circuits 335, 336 which are connected to them

  are set to "1" or: reduced to "O" so that, con-

  jointing with doors 337 and 338 which are connected to the output of door 333 and the rocker circuit 335 or to the output of door 334 and the rocker circuit 336, an impulse is produced at the output of door 339 only when a synchronization signal has been received in the forward direction and the previous synchronization signal has been identified - also during a forward movement, or when a synchronization signal has been received in the forward direction reverse and that the previous synchronization signal had also been identified during a reverse movement. To this end, the two inputs of gate 339 are connected to the outputs of gates 337 and 338. It is thus ensured that on the appearance of the synchronization signal, a complete pulse train,

  blocked, is present in the shift register 331.

  The shift register 331 with 12 positions including the

  twelve outputs are assigned to the values 24 to 215, is con-

  connected to the twelve-position input of a memory 340 which re-

  receives the contents of shift register 331 when it receives

  at its command input E3 a pulse produced at the output

  door 339 by an increasing transition.

  But when identifying a synchronization signal,

  tion, the read head 313 is no longer in a po-

  sition which has just been read, but already in a posi-

  tion assigned to the next pulse train. For this reason

  sound, the twelve-position output of memory 340 is con-

  connected to an adder-subtractor circuit 341 which, when

  that it receives a signal "1" at its addi-

  tion increases a value, and which in the presence of a signal "1" at its input of subtraction operation reduces this value, namely 2 in the present case. The first of these operation inputs is therefore connected to the output of door 333 while the other is connected to the output of door 334. In the absence of signals at the operation inputs

  of the adder-subtractor circuit 341, the information

  12-bit input is transmitted directly to the output. Immediate

  immediately after an addition in the case of a counting operation or a subtraction in the case of a counting operation

  counting down, and identifying a synchronization signal

  tion at gate 342, the result of operation in the circuit

  adder-subtractor 341 is received in memory 340.

  For this purpose, the output of the circuit 331 is connected to a second twelve-position input E2 of the memory 340. The

  gate 342 is connected to the control input E4 of the mete

  moire 340, for decreasing transitions. The two in-

  Inputs from gate 342 are connected to the signal line from the signal receiver 316 and to

exit from door 332.

  The value retransmitted to memory 340 via the

  middle of the adder-subtractor circuit 341 constitutes with the value of the counter 319, the position value at sixteen bits, representing an absolute position. Using the method described above, this position value is checked

  again every sixteen steps and it is corrected automatically-

  in the event of a fault. No backtracking in posi-

  Mechanical "0" is therefore not necessary after switching on.

  device voltage or after a power interruption

  tion. All that is needed is a short retreat from a distance within which

  the evaluation circuit shown in Figure 7 can restore the value of a pulse train. With the circuit

  corresponding, this can already be done after sixteen steps.

  In the circuit of FIG. 7, and for reasons of simplicity

  The evaluation is carried out so as to start with a synchronization signal, so that an identification can be made at the latest after thirty-two steps. It is also possible to arrange the read head 313 so that it is movable on its support piece, and to impart a relative movement to it on this support piece at the connection of the power supply, so that when system running or after a power interruption,

  the absolute position is determined without it being necessary

  make sure that the head to be positioned is moved itself.

  As shown in Figure 8, it is possible to

  provide instead of memory 340 and the adder circuit

  subtractor 341 connected to it, a counter 343 whose input EO with twelve positions is connected to the twelve outputs of the shift register 331. This counter 343 is loaded with the train of pulses present in the shift register 331 when the output from door 339 gives a signal on a

  increasing transition, because the exit from gate 339 is cons

  connected to the corresponding counter control input. In addition, a "Counting" input of counter 343 is connected to an output of counter 319 to which a signal appears when an overshoot is produced. In addition, a "Countdown" input of counter 343 is connected to an output of the

  counter 319 at which a "Hold" signal appears.

  Since, as already mentioned, when identifying a synchronization signal, the head

  313 is no longer in a correct position

  laying in a position which has just been read, but already assigned the following pulse type, the counter 319 is arranged so that when it changes to "O" or to "1" it delivers a pulse at its output or at its carry out, causing an increase or a reduction in the

  value of the pulse train loaded in counter 343.

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  The content of counter 343, together with the content of counter 319 therefore also forms a sixteen bit absolute position value. The arrangement of the other circuit elements in Figure 8 corresponds to that of the embodiment of the

  Figure 7, because for this part, the two circuits are identical

  ticks. Since in the absence of an information train on the clock track 310 ', a reading device such as those shown in FIGS. 6 to 8, like the other embodiments, continues to function correctly by incremental counting, additional information can also be transmitted or distributed instead of the absolute position values. Figure 9 shows a mode of

  achievement like this. Since this circuit corresponds to

  lay largely to those of Figures 7 and 8, the same components

  that those of these Figures are designated by the same referen-

  these. In order to avoid repetition, it is advisable to

  refer to Figures 7 and 8 for the description of the elements

correspondents.

  The embodiment of FIG. 9 starts from the fact that a fifteen-bit item of information is sufficient to represent an absolute position value. The bit thus freed is used to identify whether it is position information or additional information. If this most significant bit in the code is not at state "1" and if it appears

  a signal "0" at the corresponding output of the shift register

  ge 331, the command to load the counter 343 connected to the shift register 331 is transmitted from door 339

  at the loading input of this counter 343 by means of

  diary of a door 344. The evaluation circuit then operates in the same manner as in the embodiment of FIG. 8. If on the other hand the most significant bit is in the state "1", the command to load from the door

  339 is only retransmitted by a door 345 and informs them

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  additional dances now found dancing

  shift register 331 are received in memory 346.

  The counter 343 continues to operate correctly so -

  purely incremental lesson by the pulses coming from the counter 319. As shown in Figure 9, an input of each of the two pins 344, 345 is connected to the output of the

  gate 339 while the other input is connected to the output

  tie of the shift register 331 corresponding to the most significant bit. The inputs of the additional memory 346 are connected to the eleven outputs of the shift register 341

  to which the counter 343 is also connected.

  Reading the information by permanent counting in the form of the absolute values of the positions or in the form of other information, both in the forward direction and in the reverse direction, is obviously not limited to this mode of realization which includes

  the layout of the tracks shown in Figure 6.

  For the measurement of angular movements or rotations, it is possible to use a spiral or helical arrangement of the tracks. If there is a track with constantly repeating signals, such as a clock track, that track can be

  arranged in the form of a circle outside the dis-

spiral position.

  The manufacture of the tracks described above can be done without difficulty using a photosensitive support material. The support material cut on demand is driven in front of a light emitter, its movement

  can be mechanically associated with a po-

  current type. A computer which has received the mathematically predetermined track layout, switches the light emitter on or off according to this equation and

  the position value received. Copies can be made

  read in a simple way from their original exposed

and developed.

21 2487552

Claims (7)

  1 - Apparatus for reading information which is recorded in binary coded form in at least one information track, with at least one read head which, by means of a reading device, produces pulses under the effect an angular or linear relative movement in the longitudinal direction of the track between the read head and the; track, and to which an evaluation device is connected, apparatus characterized in that the track (10;) or at least one track (210; 310) if there are two or more (210, 210 '; 310, 310' ) contains information   additional, the read head (13; 113; 213; 313) includes   bearing on. minus an additional reading device (16, 16 '; 116, 116'; 216, 216 '; 316, 316') which receives the   additional information during reception of sig-   depending on the linear or angular position.   2 - Apparatus according to claim 1, characterized in that the additional information is recorded on the track (10; 110; 210, 310) in the form of at least one word in binary code, the evaluation device (17 - 24;   217 - 22.5, 319 - 346) combining the pulses received from the device   additional reading positive (16, 16 - '; 16, 116'; 216,   216 '; 316, 316 ') with the impulses which depend on the mo-   angular or linear, and compose them in one word in binary code.   3 - Apparatus according to claim 1 or 2, charac-   tered in that the additional information represents   try at least one absolute position value.   4 - Apparatus according to claim 3, characterized   in that each absolute position value is saved   entry on the track (10, 110; 210; 310) in the form of a series of readable markings in series, the beginning and the   end are specified by a synchronization signal.   - Apparatus according to any one of the claims   1 to 4, characterized in that the pulses which depend   tooth of the linear or angular movement consist of a   series with the same stride length.   6 - Apparatus according to claim 4 or 5, charac-   terized in that the absolute position values which form   ment an increasing or decreasing series by steps of the same height are recorded in a first track, (210, 310) in sectors of the same length immediately following one another, each of the sectors of the same length of a second track (210 '; 310'), associated with a sector of the same length of the first track (310, 310) being divided into equal steps the number of which is equal to the   difference between the values of two following positions   wind, or an integer fraction, or an integer multiple of this number-   7 - Apparatus according to any one of the claims   1 to 6, characterized in that the track (210; 310) in which additional information is stored   is spatially separated from a track (210 '; 310') in the-   what is counting information   - 8 - Apparatus according to any one of the claims   1 to 7, characterized in that the evaluation device tion has a microprocessor.