DE2953323A1 - PHOTO-OPTICAL KEYBOARDS - Google Patents

Description

Photo-optical keyboards

The present invention relates to the field of keyboards.

Photo-optical keyboards of various types are known from the prior art. For example, U.S. Patent No. 3,856,127 describes certain types of keyboards. The keyboard primarily disclosed in this patent has a number of light channels arranged in rows and columns, with light sources being arranged at one end of each channel and photodetectors being arranged at the other end of each channel. The channels representing the rows have a different depth than the channels representing the columns. With each key two panels are coupled, which are arranged in the section \ on two channels, so that each panel can block one of the adjacent channels. If you press a button, one of the panels coupled to it blocks a light channel line, the other panel blocks a light channel column. Each key can consequently be based on those column and row identify that when P ¹ CKEN "this key will be blocked. The system has the advantage that not for each key a separate light source

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and a dedicated photodetector is required; however, there are certain disadvantages in terms of complexity and the mode of operation. The required light channels are relatively expensive to manufacture and the The patent does not disclose any measures to solve the problem of pressing multiple keys at the same time. There too There are always slight differences between the apertures, light channels, light sources, detectors, etc., can Partial pressing of two keys that are not in the same row or column Pressing a third key interpreted, which lies in the intersection of the rows and columns, as a cover of a key one row and the opposite Can lock the associated channel. Even if you press both buttons is detected, no means is provided to determine which key was pressed or released first will. Other embodiments have mirrors on each button that work at the junctions of the channels, so that each key casts the light from the row light sources onto the column light detectors. In such a Systems, as indicated, must employ scanning means, although details of such means are not given are. This patent also discloses a fiber optic device, among other things.

Other photo-optic keyboards or key feeler systems are disclosed in U.S. Patents 3.6o3,982, 3,648.o5o, 3,737,668, and 3.75o.15o specified. However, these systems are fundamentally different from the present invention and lack in them general the simplicity of construction and the versatility and reliability in use that the present Identify invention.

The present invention relates to photo-optical keyboards which provide electrical signals when the keys are pressed. the

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The keyboard consists of an arrangement of individual keys that are specially arranged and labeled and make a longitudinal movement when pressing. There is a matrix under the multitude of keys Light sources and photodetectors, which are arranged so that when a certain key is pressed, the light path between one of the light sources and one of the detectors • is interrupted, so that in the associated circuit an electrical Change of state takes place. The light sources and detectors are arranged so that generally a single light source illuminated multiple detectors and each detector can be illuminated by multiple light sources, so that the The number of light sources and sensors required for the entire keyboard is considerably lower than the number of keys to be captured. Furthermore, a microprocessor-controlled system for scanning the light sources and Detectors disclosed. In general, individual light channels are not required in the keyboard, as this is the case Scanning method eliminates unwanted coupling effects.

Figure 1 is a top plan view of an exemplary keyboard according to the present invention;

Figure 2 is a side elevational view, partly in section, of the keyboard of Figure 1;

Fiq. 3 is a partial section through a typical key on level 3-3 of Fiq. 1;

Figure 4 is a bottom plan view from plane 4-4 of Figure 3;

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Fig. 5 is a top plan view of the sensor board showing the relative placement of the light sources, detectors and Buttons shows;

Fig. 6 is a partial section on the plane 6-6 of Fig. 5 showing the general arrangement of the light sources and detectors;

Figure 7 is a block diagram of the microprocessor board of the exemplary embodiment shown in Figure 1;

Figure 8 is a circuit diagram of the sensor board of Figure 5;

Fig. 9 is a flow chart for the sequence of operations of the microprocessor ; and

Fig. 1o shows an alternative key shaft shape with which can reach an illuminated keyboard.

Fig. 1 shows an embodiment of a keyboard of the present invention as a plan view. This particular keyboard contains sixty keys in a 5 χ 12 rectangular field on a 2o plate with mounting holes 22, via which it can be inserted into a chassis 24 (see FIG. 2) using the screws 26. the individual keys 28 of the keyboard are individually numbered from 1 to 6o, so that in the following description on them can be referenced quickly and easily; for the im

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On a case-by-case basis, the keys can of course be assigned different combinations of numbers, letters, Designate control characters etc.

FIG. 2 shows the keyboard of FIG. 1 in a side view. The individual keys 28 are mounted on the upper side of the circuit board 2o, the plate being closed on the rear by a cover 3o through which a cable 32 runs at an appropriate location. As explained below, the cable 32 typically contains the lines , via which the supply voltages are fed to the electronics contained in the keyboard arrangement, as well as output lines organized in series or in parallel, depending on the desired arrangement of the output lines ^; signals. Within the cover 3o there are two circuit boards 32, 34, the board 32 being referred to here as the sensor board and the board 34 as the microprocessor board.

3 and 4 now show a section through a typical key, for example on the level 3-3 of FIG. 1 or a Key mechanism from below. In this embodiment, the stationary part of the key, i.e. the key body, is made up of an upper body member 36 and a lower body member 38, the lower body member having an upwardly protruding one Part 4o which runs through an opening in the plate 2o and is locked into the upper body part 36, so that the two elements are fixed cooperatively firmly on the two sides of the plate 2o. The ones in plate 2o for the Key body members 38 provided openings are generally circular and are in the illustrated embodiment; widened in two places to receive a fitting nose 4o with which the angular position of the lower body element is determined will. Analogously, the key shaft 42 is general in cross section

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designed in a cross shape (see. Fig. 4) and sits loosely and displaceable in a cross-shaped opening on the underside of the lower body element 38, so that the key shaft is held in this in a certain angular position. The upper part of the key shaft 44 is also in cross section cross-shaped and pressed into an adapter, 46, onto which a key cap 48 can be pressed, the respective Designated key and designed it individually for a specific application. The middle area 5o des The key shaft is generally circular, lies within the inner diameter of the lower body member 38, and is resiliently pressed into its uppermost position by a helical spring. Immediately below the lower part 42 of the key shaft is the sensor board 32, so that when you press the button, the lower end 42 of the key shaft down to the Circuit board is pressed. The lower limit of movement for each key can vary with the mechanical limits of the key arrangement or by placing the lower end 42 of the key shaft on the sensor board. Farther you can provide openings in the sensor board 32 below each key shaft into which the key shaft comes in.

5 shows a schematic plan view of the sensor circuit board 32. The keys 42 of the sixty individual keys are shown in dashed lines in the figure and numbered 1 to 6o as above :. Furthermore, this figure shows eighteen light-emitting diodes 54, lie in a special arrangement with regard to of the keys 42 are distributed, as well as twenty-one Phototransistors 56, which are also arranged in a special way with respect to the key shafts. For reasons that will be discussed in more detail below, the light-emitting diodes 54 are divided into eight groups, which are designated by the letters A to H. As Fig. 6 shows,

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the top row of LEDs contains two LEDs assigned to group A; this group does not include light-emitting diodes assigned from the second or third row of LEDs. Groups F and G each contain three light-emitting diodes, the remaining groups only two. Accordingly, the phototransistors 56 are combined into eight groups, which are designated 1 to 8 in the following.

As in the upper left part of the sensor board 32, i Visibly, the first light-emitting diode 54 assigned to group A directs light (see the dashed line) under the key shaft 42 of switch no. 1 through onto one of the phototransistors 56 of the detectors of the group 8. The same light emitting diode directs light under the; Press key no.13 on one of the detectors of group 7, under key no. 14 on one of the detectors of group 1 and under button no. 2 through to one of the detectors of group 5. The other LED of the Group A directs light under buttons 9, 1o, 21 and 22

'4 through to the detectors in groups 6, 4, 2 and 3. j

If only the light-emitting diodes belonging to group A light up, light falls on one and only one phototransistor each of the eight detector groups. If one of the buttons 1, 2, 9, 1o, 13, 14, 21 or 22 is pressed at this time. If the respective key shaft 42 interrupts the associated light beam, one of the eight detectors or, what is more important is one of the detectors from one of the eight groups no longer lit; from this fact it can be determined that the key has been pressed. The general organization of the LEDs and detectors is as follows Table compiled:

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Detector group

1 2 3 4th 5 6th 7th 8th 14th 21 22nd 1o 2. 9 13th 1 15th 16 23 11 3 4th 24 12th 47 17th 35 18th 6th 5 36 48 26th 2o 38 19th 7th 8th 25th 37 27 23 39 X 56 4o 55 X 58 29 5o 3o 57 41 42 49 59 32 51 31 44 52 43 6o

A B C D E F G H 46 33 34 X 45 53 54 X

In principle, eight detectors can be assigned to each light-emitting diode group, so that combinations of eight or sixty-four possible assignments of a light source with a signal source are obtained. Since the one here is ^; The embodiment described is a keyboard with 60 keys, four of the possible combinations do not occur; they are labeled "X" in the table. The 8x8 assignment and the general arrangement of the light-emitting diodes and the detectors can obviously be changed for a special keyboard, other key numbers or the like, depending on the application, although the 8x8 matrix for control and data reduction with an 8-bit microprocessor is particularly cheap. As can be seen from a consideration of the. Table, each key (for example key no. 56) can be detected by activating or energizing the light-emitting diode group of the row assigned to this key in the table (and only this group, ie group E for key no. 56) and then the state of the detectors in that

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Checks the group in whose column the respective key is located (group 5 for key no. 56).

Before the electronics and the means for operating the keyboard are explained further, certain ones should first be explained Properties and advantages of the keyboard arrangement just described are explained. Preferably the luminous; diodes 54 wide-angle. Light-emitting diodes with this property are produced in large quantities and, for example, in Control and indicator lights used; they are therefore inexpensive in the trade. The one in the preferred embodiment The light-emitting diodes used in the present invention are manufactured by Fairchild and sold under the Designation FMV5o52 offered. Correspondingly, the phototransistors 56 are also wide-angle detectors; in In the embodiment described here, photo transistors of the type 21-L14H2 from Motorola are used. It has found that optical coupling can be kept to a minimum by suitable excitation and detection; individual Light channels to define the possible light paths and to prevent undesired light paths are then generally not necessary, so that the effort for the creation of devices and the manufacturing costs are significantly reduced. For example, the top left light emitting diode 54 in group A generally does not provide enough light for that too third phototransistor 56 in the first row of phototransistors (Group No. 6) is illuminated so that no structural elements are required to make this possible To block the light path. It should also be noted that many of the LEDs in the top row are for the detectors are not "visible" in the middle line because they are from the LEDs of the second row are switched off. It has been found, however, that the top line of the luminous

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diodes can occasionally illuminate the bottom row of the detectors so strongly that they produce false output signals receives. As explained below, however, most of the detectors in the lowest row of detectors are switched off when one the light-emitting diode groups A to D is controlled (in this embodiment, no light-emitting diode group contains light-emitting diodes in both the first and the third row of LEDs!).

FIG. 6 is a section on the plane 6-6 of FIG. 5. This section shows the arrangement of a typical light-emitting diode 54 and a phototransistor 56. Generally speaking, both elements protrude on their terminals by a suitable height the sensor board 32; the connecting wires run through holes in the circuit board and are soldered on the other side. If, for example, strong vibrations occur in a special application, a spacer can be placed under each element or provide a support; in general, however, it is desirable to arrange the light sources and sensors in such a way that that the key shaft can protrude far into the light path between them and preferably through it. Is in the sensor board 32 under each key a hole is provided, one can of course the light sources and detectors essentially arrange them flat on the board.

In the preferred embodiment of the invention, the keyboard is different from that shown in Figures 7 and 8 as a block diagram Circuit controlled by a microprocessor. In the microprocessor used in this embodiment it is the type 8o48 from Intel Corporation, Mountain View, California, V.St.A. A 6 MHz quartz 6o sets the clock rate fixed. Port P2 with lines P2o to P27 serves as the output port, another port P1 with lines PIo to P17 as input port. There is also an 8-bit data

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bus DB, whose first line DBO is part of the keyboard control is. The remaining bits (DB1 to DB7) can be used as keyboard signal output lines serve, the line 1 having an optionally desired serial output and several lines in common represent a parallel output. As shown in the figure, lines P2o to P23 of port P2 provide the Signals A, B, C and D; all lines P2o to P27 become the signals EA1, EA2, EB1 etc. to EH2 with the inverters 62 inverted. As already mentioned, the light-emitting diode groups F and G each contain 'three light-emitting diodes, the remaining groups only two at a time. Fig. 7 shows that the signals on lines P25, P26 with three inverters each to the three signals EF1 to EF3 or EG1 to EG3 can be inverted. As can be seen in the following, a signal is used on line 2o, to generate the two signals EA1 and EA2 to control one of the two light-emitting diodes in group A, etc .; the three light-emitting diodes in groups F and G are controlled individually with one of the inverter output signals the lines P26, P26 have been derived. In the preferred embodiment, these are the eighteen inverters 62 by three 6-way Darlington driver modules of the type 75492 from Texas Instruments.

The first port P1 is used as an input port, the signals D1 to D8 via the Schmitt trigger 64 on the lines P1o to P17 are set (the eight Schmitt triggers are in the preferred Embodiment in the form of two 4-way Schmitt trigger modules of the type MC-14584 from Motorola).

Fig. 8 shows the circuit layout on the sensor board eighteen light-emitting diodes 54 and the twenty-one phototransistors 56 of this figure are arranged in the matrix shown in FIG. 5. All emitters of the phototransistors of the first

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both lines are grounded; the emitters of the phototransistors of the third row are, however, applied to the outputs of the OR gates 66, 68, 7o, 72 (in the preferred embodiment 4-way OR modules MC-14o71 from Motorola). The input signals of the OR gates are signals A to D, so that the emitters of the phototrarisistors in the lower row are connected to ground only depending on the signals A to D. The emitters of the first two phototransistors in the bottom row are only connected to ground when the output of the OR gate 6 8 and thus also the output signal of the OR gate 66 is log.L or when A, B and C are log.L. Corresponding the emitters of the two right phototransistors in the lower row are only connected to ground if A, B and D are log. L, while the emitters of the three middle phototransistors are connected to ground (i.e. log.L) when A, B, C and D log.L are. In principle, this connection is complementary to the grouping of the phototransistors: the first light-emitting diode in the second row is assigned to group D and illuminates the first two phototransistors in the lower row, while the The last light-emitting diode in the second row is assigned to group C and the last two phototransistors are assigned to the lower one Row lit. The middle three phototransistors in the bottom row are not functionally any of the light-emitting diode groups Assigned to A, B, C or D.

As already mentioned, the light-emitting diodes with the signals EA1 to EH2 are corresponding to the marking given in FIG controlled. The other connection of each light-emitting diode is connected to one of the resistors R1, R2, R3, which is connected to the positive one Reference voltage. The resistors R1 to R3 represent current limiting resistors for the light emitting diodes; three Such resistances are sufficient, since no more than three light-emitting diodes are activated at the same time

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and in the circuit shown in Fig. 8 in each particular one Point in time within a work cycle, there is never more than one activated light emitting diode at each resistor. In the end The collectors of twenty-one phototransistors 56 on data lines D1 through D8 (FIG. 7) are those shown in FIG Way, with each of these lines with an associated Pu11-up resistor 74 normally connected to log.H is. (Fig. 7).

Before the logic diagram is described in detail, the electrical properties of the interconnection of the LED-phototransistor pairings should be noted received with the rest of the circuit. It is assumed here for explanation that the microprocessor the line P2o puts on log.H, while the lines P21 to P27 are log.L. The signals EA1 and EA2 are therefore logical L, the other signals log.H. When EA1 becomes log. L, the first one lights up LED in the first line on; If EA2 becomes log.L, the penultimate LED lights up in the first line (Fig. 8). If all keys are in the idle state, the light emitted by these two light-emitting diodes is emitted by the four phototransistors detected, which are assigned to each light emitting diode, so that eight signals are on the data lines D1 to D8. The lines D1 to D8 have a very small but finite capacity. Are all lines initially on log.H, discharge quickly, but at a limited rate to the state log.L. A phototransistor is constructed in such a way that light can fall on its base area; this light produces there minority carriers proportional to the strength of incident light. This process is equivalent to feeding a certain limited base current into a conventional one Transistor so that the transistor acts as a current source. The. ; Power source discharges the capacitance of the lines DI through D8 so that the speed at which these lines by log.H. go to log.L, of the resistors 7 4 and the

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Phototransistor current depends. M.a.W .: The length of time that it is necessary that one of these lines approaches the level of log.L far enough to switch the Schmitt trigger 64 to leave depends on the strength of the particular phototransistor falling light. If all keys are in the idle state, the incident light is proportionate strong, so that the lines D1 to D8 let the Schmitt triggers toggle within a few microseconds after a of the lines P2o to P27 a certain group of LEDs

has excited. If one of the keys in this LED! If the key group assigned to the group is pressed, the key shaft weakens the light falling on the associated phototransistor to such an extent that the speed at which the associated data line D1 to D8 is discharged is slower. In the preferred embodiment, the pressing of a key is therefore determined on the basis of the fact that the Schmitt trigger for the associated data line does not switch over within a given period of time after the associated group of LEDs has been energized. Specifically, in the preferred embodiment, approximately two milliseconds after energizing each light emitting diode 'group provided within which all of the data lines D1 to D8 j must go to log.L. If one of these lines has not reached the level required to trigger the associated Schmitt trigger, the microprocessor treats this key or keys as being pressed. After a key has been determined to have been pressed, it is determined in subsequent runs within about one millisecond whether the key has been released. In this way, a certain hysteresis is generated for each key, since less light is required to detect a pressed key than to detect a key release; the switchover point is lower when the button is pressed than when a key is released. Since the various lines continue to have capacitance and the lines D1 to D8 have to be recharged in each operating cycle, the output data bus line DBO receives the level

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log.H immediately before each LED group is activated, so that the lines D1 to D8 via the diodes 76 again to log.H be placed. In the following description of the logic diagram, the loading of these lines is referred to as "quenching", since the effect of this signal is to bring all data lines into a state in which the next group of LEDs can be controlled.

Figure 9 shows a typical flow chart for programming the microprocessor. The system normally turns on when all keys are idle. When the system is switched on, the program initializes the system by setting all lines of port 2 to logical O, registers 32 to 39 consistently to logical 1 (FF in hexadecimal notation), a register G = 01 (hexadecimal), a register D = O and sets a TRIGGER register = 0. Registers 32 to 39 represent a map of the keyboard; they serve as an 8x8 matrix memory with the content of which the eight data signals for each of the eight LED groups can be compared. Register G receives a number that indicates which LED group is switched on, while another register contains a bit to log.H, which is shifted to the left in order to control the LED groups cyclically via port P2. Register D contains a number that indicates how often the electronics have not detected any key actuation. It is always incremented if no key has been pressed and is used to reset the TRIGGER register. The TRIGGER register acts as a status mark ("flag"); TRIGGER = 0 registers a key, ie provides an output signal for this key when it has been pressed, while TRIGGER = 1 only registers this key when the key is released. As can be seen below, is registered with the simultaneous pressing of two buttons one of them until the release. The key function is then determined by the first key that is released. (During initialization, a KEY register is also displayed as an error message

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log.O set. Finally, a will appear during initialization Erase pulse to charge all data lines. These various functions are generalized in block 101 of FIG. 9 summarized. The next step (block 1o2) is to switch off the erase pulse and to set a time value to zero. This The time value is in a register that is part of the basic scanning sequence is incremented periodically and determines the mentioned time periods of one and two milliseconds. One with Register designated PASS is set to 0 or 1 in indi- j direct dependence on the fair value, as can be seen in the following, j

In the next step (block 1o3) the eight detector signals on lines D1 to D8 are read. So that all paths: appear open (block 1o4), the lines D1 to D8 must all be pulled to logical L; as already mentioned, is this requires a certain amount of time, even if all keys are idle. The first test is therefore probably not all lines open so that the time value is incremented in block 1o5 and a test is made in block 1o6 to determine whether it is a Millisecond has reached; if this is the case, that determines j

ι System further whether the key press or key release information - depending on the status of PASS - must be upgraded ("updated"). If the time value of one millisecond has not been reached the program jumps back to A, reads the detectors again (block 1o3) etc. and continues to run cyclically until either the time value for one millisecond is reached or all paths turn out to be open. "Are, all keys are idle, port P1 takes about 10 microseconds after switching on the respective LED group the value FF. If this is the case, PASS is checked (block 1o7); it turns out to be zero. PASS = 0 corresponds to the state in which the system searches for released keys, while with PASS = 1 it checks for pressed keys. Since all buttons of the first LED group are at rest (since all paths are considered to be open.

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have turned out), a change in the released keys can be checked immediately. So at this point, D increments (block 1o8) and checking for enabled keys continues in block 125.

A buffer register is used to check for enabled keys loaded with a mapping of the pre-existing state of this group, as it is in one of registers 32 to 39 (initially set to FF) according to the count value in register G, which, as already mentioned, the respective represents currently switched on LED group; this is referred to in block 125 as MAP (G). After that, MAP (G) will be upgraded, by using MAP (G) with the 8-bit signal at port P1 (i.e. the data lines D1 to D8) is ORed Since initially both MAP (G) and P1 are consistently logical H (the data lines D1 to D8 are logical L, de all keys are in the idle state MAP (G) does not change. Furthermore, at this point in time PASS = PASS + 1 and the time value are set to zero. In block 126, TRIGGER is checked; since this register has been since Initialization in block 1o1 has remained zero, it jumps System back to block 1o3 and reads the detectors again, to find that all paths are open. At the transition this time PASS = 1 is determined for block 107; this switches off all the light emitting diodes, and all of them with the extinguishing pulse Data lines loaded to log.H and the register G incremented (Block 11.6). If G = 8, there is a transition to block 129, where a new LED group is selected by adding the content of port 2 is shifted one bit to the left. The erase pulse is switched off, the time value and PASS to zero reset and read the detectors again in block 1o3. If G!> 8, this indicates that all LED groups have been checked have been, G = 1 is set in block 118 and the system jumps to the output sequence, starting with the block 12o.

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In block 12o, D is tested to see if D = 8. If so (D ranges from O to I) ₁ , TRIGGER = O is set so that the system registers a key when it is pressed. If D Φ 8 (indicating that not all eight LED groups have been checked), the system further determines whether a key has been registered as a result of the operations in blocks 115, 128. (In this example, all keys are idle; so no key has been registered.) If a key has been registered, ie KEY φ O, the system outputs this key on one or more of the output lines DB1 to DB7, but sets it in any case D = O and loops back to block 129 to start the sequence again.

This sequence of steps is repeated continuously as long as it is complete Keys are in the idle state. However, as soon as a key is pressed, the test is carried out in block 1o4 whether all Paths are open only after the time value has reached one millisecond (block 1o6), in which case the system denies Checks the state of PASS, which is of course still zero, as previously set in block 1o2. The system therefore now checks for the Enable keys by going to block 125 Da MAP (G) =

FF, there is no increase in the OR link in block 125 tion. After PASS = 1 has been set and the time value has been reset, the system goes back to block 1o3, since TRIGGER = 0. (In general, the light-emitting diodes will be operated with a high average current in order to keep their light intensity high. if you partially press a key, the duty cycle for this one LED group increases, you can also use the microprocessor program in such a way that it detects this state and inserts an empty interval ("idle mode") so that the limit values of the LEDs are not exceeded.)

After returning to block 1o3, the sequence of steps of the

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Blocks 1o3 to 1o6 are repeated continuously until the time value again reaches one millisecond. Since PASS = 1, a check is carried out in block 11o to revalue the keys pressed. In particular, MAP (G) is again entered in the intermediate register and then the registers 32 to 39 corresponding to the numerical value G are upgraded according to the keys pressed by adding MAP (G) to P1, i.e. the eight bits of the microprocessor port P1, is ANDed. If only one key has been pressed one of the lines at P1 is at log.L, so that the corresponding bit of the corresponding register of the register group 32-39 is set to log. L (if two or more buttons of the group under test have been pressed, the de- • speaking two or more bits set to logical L). After that! the time value is set to 0 and TRIGGER is checked. Since TRIGGER = : 0 applies (since block 1o1; not changed so far), the The contents of the intermediate register in block 112 are compared with MAP (G). If only one key is recognized as being pressed, a subsequent; lookup table determines which key it is. and this key is written into the KEY register. j j The program then jumps to block 116 and continues as]

j

I described above. It should be noted that the test \ of block 113 is a global test, because in each individual

: LED group can have been pressed more than one key; the same can one pressed button in an LED group, a second one

. Pressed key appears in a second LED group. The in The output sequence beginning block 12o is only initiated if G > ■ 8 results. If more than one key has been pressed, as shown in the test in the block results, the register KEY = 0 is set, which indicates an error, and TRIGGER = 1 is set; then the sequence goes to Block 116 over. With KEY = 0 (error message), the test in block 122 shows that no key has been registered, so that no output signal is given either; instead the system loops back to block 129 and examines those of the next Detectors assigned to the LED group. So it will be the whole

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The keyboard is queried to determine whether one or more Buttons have been printed; if more than one key has been pressed, TRIGGER = 1 and KEY = 0 are set. The system then scans the keyboard further by switching on all the LED groups one after the other, interrogating the detectors and interrogates registers 32-39 for each key pressed thereafter by upgrading in block 11o, but does not go to block 112, as a result of the state of TRIGGER, as it results in block 111. Because of the status of TRIGGER, however, the check for released keys is carried out up to blocks 125, 126. If the Checking in block 127 a difference between the buffer register and MAP (G) is again made from the look-up table determines the released key and identifies this key in the KEY register, after which the system returns to block 1o3, finally runs through the entire output sequence and outputs the first released key via block 123. So are two or more keys pressed at the same time or two keys and then additional keys are pressed before the first two have been released, the system does not keep the order in which the keys were pressed, but the order in which they are released.

So far it is an exemplary embodiment of one novel keyboard as well as exemplary hardware and software for Scanning of keyboards has been described to determine the order in which the outputs are pressed and / or Identify key release. The preferred embodiments have the advantage that no individual light channels required are; instead, one arranges a multitude of light sources and light detectors in such a way and one another electrically to that the pressing of a key is determined by the fact that the light bridge between a light source and a detector is interrupted. The arrangement allows a single light source for several detectors and, accordingly, one detector

for multiple light sources so that the number of light sources and detectors required for a given keyboard can be kept to a minimum. Since the detection signal is determined from the interruption of a light path, not by reflection or transmission of light, one obtains in comparison to constructions working with light reflection in which the accuracy of the adjustment and the cleanliness of the reflective surfaces for practical use _; represent critical factors, a necessarily flawless function. Furthermore, the microprocessor-controlled scanning system, as disclosed here, automatically offers a switching hysteresis with which double switching (such as when bouncing mechanical switches) can be prevented; the result is a system that can also be used in environments with strong mechanical vibrations. Since the mechanical part of the keyboard has a very simple structure, the switching processes do not depend on the closing of mechanical switches. The sensor and the microprocessor board can be immersed to ensure moisture resistance; the keyboard therefore remains operational even if it is wetted, ie, for example, coffee is spilled over it. While in the preferred embodiment the switching hysteresis is generated by means of the time behavior of the photoelectric part of the keyboard, other possibilities can also be used here - for example an electrical or mechanical hysteresis. The light sources and the light detectors in the form of phototransistors, photoconductors or photocells can also be arranged in different arrangements and matrices; this is preferably done so that the states of each key can be clearly identified with just a single scan. An obvious alternative in this regard is to block the light path when the key is released and to open the light path when the key is pressed.

As a further alternative, you can use any key shaft, any adapter

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ter and each cap run at least semi-transparent, the lower end 80 of the shaft (see. Fig. 1o) the light-emitting diodes facing is angled. As long as not at least the shaft surface 82 facing the phototransistors essentially is transparent, the keyboard operates as described above; in addition, each key appears as a result of the Key cap emitting light from the 'light-emitting diodes (preferably diffuse) is illuminated. It is true that light can then also enter the keyboard housing penetration; however, it is directed at the light-emitting diodes, not at the phototransxstors and can therefore be their Do not disturb function.

030601/0059

Claims (1)

-3 U ^: BERLIN 33 * ° '8 MUNICH AugiMte-Vilctorlt-StraS «SS p. DIICOUI / C Λ DADXMCD PIemen «uer« tr «Be2 Pt app. OrInB-RuSChK. Dr. RUSCHKE & PARTNER P. «, Anw.Olpl, lng. XA ¹ ST ¹ * PATENTANWÄLTE ^H "· ^E - ^{Rutchk #} _M03M BERLIN -MONCHEN ^ '' '"" ^! F Telegram address: Quadrature B. To TeUgmmm-A *. ·· .: _T e ι cv. λ at 7οβ quadrature Munich TELEX. 183786 TELEX: 522767 Munich, July 15, 198o O 459 H. OPTICAL TECHNIQUES INTERNATIONAL, Inc., 145o West 228th Street Suite 13, Torrance, Calif., / USA Claims 1. Photo-optical keyboard, marked by a key arrangement with a first plurality of individual keys Keys, each between a shared and are movable in a pressed position and contain means which elastically bias the button into the release position, a second plurality of light sources, the second plurality being smaller than the first plurality, a third A plurality of light sensors, the third plurality being smaller than the first plurality, and at least some of the light sources are arranged so that they focus on different parts of the light you emit Set up light sensors, and the latter light sources and light sensors are assigned to certain of the buttons, so that each of the last-mentioned keys block the passage of light from a .Lichtquelle to a light sensor substantially when it is in the released or the depressed position, and the passage of light is essentially 030601/0059 lichen does not lock if it is in the other, i.e. pressed or released position, whereby the pressing of a button can be determined by turning on the associated light source and checking the status of the assigned light sensor determined. 2. Keyboard according to claim 1, characterized in that that each of the keys, when pressed, the passage of light between a light source and a light sensor in the essential locks. 3. Keyboard according to claim 1, characterized by a scanning device, the light sources of the second plurality turns on one after the other and the state of the associated light sensor is determined. 4. Keyboard according to claim 3, characterized by means that at least some of the not one of the light sensors assigned to the switched on light sources switches off. 5. Keyboard according to claim 3, characterized in that the second plurality of light sources is grouped into a smaller number of light source groups and that the scanning device successively each of the Turns on light source groups and determines the status of the light sensors assigned to them. 6. Keyboard according to claim 3, characterized in that the plurality of light sensors to one 0 3 0601/0059 2353323 -X- is divided smaller plurality of light sensor groups, each of the light sensor groups at least one of the light sources is assigned, the light sensors in each light sensor group parallel to the light sensors in each other Light sensor group are so that the state of the light sensor in each light sensor group on the same plurality can be determined from output lines. 7. Keyboard according to claim 3, characterized in that the second plurality of light sources is divided into a smaller number of light source groups that the scanning device successively each of the Turns on light source groups and the state of the detectors belonging to this determined that the plurality of Light sensors continue to be divided into a smaller number of light sensor groups and each of the light sensor groups one of the light source groups is assigned that the light sensors in each of the light sensor groups in parallel to the light sensors in every other light sensor group, so that the state of the light sensor in any Light sensor group on the same multitude of output lines can be determined regardless of which one Light source group is currently switched on. 8. Keyboard according to claim 3, characterized by a device which determines which key has been pressed and provides a corresponding output message. 9. Keyboard according to claim 8, characterized by <nine means that the simultaneous pressing of a A large number of keys are determined and, in response to the release of the keys, an output message from the keys in the 030601/0059 Order in which they were released. 1o. Keyboard according to claim 1, characterized in that g e k e η η that the light sources light to the light sensors without specially created light channels between them 1 ■ judge. 11. Keyboard according to claim 1, characterized in that a portion of each key is substantially is transparent and that this substantially transparent part is so that it receives light from the light sources can to illuminate the keyboard. 12. Keyboard according to claim 1, characterized in that the light sensors are conductive when exposed to light and are connected in such a way that they switch an electrical line from a first electrical state to a second bring electrical state, and that the keyboard continues to have means to the electrical line in the first Load state in order to switch on the light sources of the second plurality one after the other and the transition of the lines to the second state, which indicates that one of the associated keys has been pressed, within a first predetermined Time to determine. 13. Keyboard according to claim 12, characterized by means that the transition of the lines in the second state, which indicates that one of the associated keys has been released, within a second predetermined Time span determined, wherein the first and the second predetermined time span are unequal, so that a hysteresis 030601/0059 29533.2a IS- -χ- between the pressed and the released position arises. 14. Photo-optical keyboard, geke η η is characterized by a key assembly having a first plurality of individual keys that departures in each case between a released and a depressed position and are movable back and have means which each key preload elastically to the release position [NEN, by a second plurality of light sources smaller than the first plurality, a third plurality of light sensors, the third plurality being smaller than the first plurality and at least some of the light sensors being arranged to receive light directed thereto from different ones of the light sources The last-mentioned light sources and light sensors are arranged with respect to certain keys such that each of the last-mentioned keys can substantially block the passage of light between a light source and a light sensor when it is in the released or the depressed position, and the passage of light substantially releases when i n is in the other, ie pressed or released position, so that the pressing of a key can be detected by switching on the associated light source and determining the state of the associated light sensor. 15. Device which responds to the position of a movable element, characterized by a light sensing device, which becomes electrically conductive when exposed to light, the light sensing device being connected in such a way that it can bring an electrical line from a first to a second electrical state by means of a light source device, the light on the light sensing device so 030601/0059 directs that the passage of light can be interrupted depending on the position of the movable element, by a Device to successively charge the electrical line in the first state, to switch on the light source and to address the period of time as a measure of the position of the movable element that the electrical line needs to go to the second state. 03060 1/0059