DE102011075751A1 - Control element for transparent keyboard, for use in e.g. operation unit of working machine, has transparent support plate covering keyboard, and light barrier arranged over control surface of control element - Google Patents

Abstract

The control element (1) has a switching element (5) mechanically operated by pressure of a finger of an operator. Contact elements (4) are associated with the switching element. The contact elements are bridgeable with strip conductors or wirings (2) that are provided on a circuit board (3). A transparent support plate (6) covers the keyboard. A light barrier is arranged over a control surface (8) of the control element. The light barrier comprises two optical transmission/receiving units (9, 10) that are provided beside the contact elements on the circuit board. The transmission/receiving units are formed as surface mounted device (SMD) components, and comprise infrared (IR) LEDs or IR laser diodes.

Description

The invention relates to a control element for keyboards, comprising at least one mechanically operable switching element with associated contact elements.

Keyboards, especially membrane keyboards, are for a variety of applications, such as operating units for work machines, self-propelled agricultural machines or towing vehicles, with data display and input devices, for remote controls or the like. in use. Common feature of such keyboards are mechanical switching elements that have no electrical connection to mostly two or more switching contacts in the idle state and are contacted by finger pressure, plunger, etc. with the switch contacts upon actuation of a cover or front foil and thus electrically bridge them. As switching elements are metallized plastic films or platelets, carbon films or other elements into consideration, with which electrical contacts can be bridged. Such keyboards with front foils are also suitable for use in wet environmental conditions. So goes out of the EP 2 001 033 A1 a membrane keypad with luminous keys, in which a switching film is arranged on a carrier material, which is covered in the contact area of a snap disk. This snap disc is surrounded by a spacer foil (spacer). The keyboard is covered by a front foil. To illuminate the button is located between the snap disc and the front sheet nor a light element, such as an organic light emitting diode (OLED).

If pressure is now exerted on the front foil in the switching area, the snap disc snaps down and establishes an electrical connection between the contacts of the contact foil. When the button is released, the snap-action disc automatically returns to its original position.

A similar illuminated membrane keyboard goes out of the utility model DE 20 2007 006 647 U1 out.

The utility model DE 20 2007 016 762 U1 also refers to a membrane keypad with illuminated buttons. Here surrounds the key body a scattering body, is irradiated in the side of a light source of light.

A slightly different construction of a control element of a membrane keyboard goes out of the utility model DE 203 08 920 U1 out. These are so-called large keys that can be pressed at any point and still generate a switching pulse. Such large buttons require a fairly large area, but are quite safe to use.

In all conventional membrane keyboards, however, there is the problem that the safe operation of the switching element itself is not guaranteed. This has the consequence that a key or button is indeed pressed, but that nevertheless no switching function is triggered. The reason for this may be that the key has not been pressed with sufficient force, or that the switching element or the switching contacts have worn out, or another error has occurred.

Of course, there is the possibility of issuing an optical or acoustic acknowledgment signal, but this would require the attention of the operator in addition. This is particularly disadvantageous if the operator at the same time operates a moving or at least noisy implement, or must observe work processes. Thus, such keyboards for the operation of safety-related devices are only partially usable, especially because no switching redundancy is available.

The invention is based on the object to provide a control for keyboards with a particularly high level of reliability.

The object underlying the invention is achieved by an operating element for keyboards, comprising at least one mechanically by finger pressure actuated switching element, with the associated contact elements on a circuit board provided with printed circuit board can be bridged, wherein the keyboard is covered by a transparent support plate and wherein on the Operating surface of the control element at least one light barrier is arranged.

The light barrier advantageously consists of two optical transmitting / receiving units each adjacent to the contact elements on the circuit board, which are optically coupled to each other via deflecting prisms on the support plate.

In one embodiment of the invention, the transmitting / receiving units are designed as SMD components which are electrically connected to the wiring on the printed circuit board, wherein the transmitting / receiving units contain IR light-emitting diodes or IR laser diodes.

In a variant of the invention, the deflection prisms are embedded on the carrier plate in a transparent film, which is recessed over the control surface. As a result, the deflection prisms can be integrated very inconspicuously, so that they too a more robust operation of the control surface withstand.

A further embodiment of the invention is characterized in that a light beam radiated from one of the transceiver units upwards through the carrier plate to a deflecting prism deflects there by 90 ° to the opposite deflecting prism and there by 90 ° down through the carrier plate to the other transmitter - / receiving unit is distracted.

The control element according to the invention can be advantageously used for keyboards with arranged in one or more rows controls, or for keyboards with a variety of matrix-like controls and is also suitable for membrane keyboards.

In a further embodiment of the invention, a plurality of side-by-side control elements can also be covered by a common light barrier, or the control elements of each row and / or column of a matrix are each covered by a common light barrier. In the latter case, each control element is located at the intersection of the light beams of two light barriers, so that an accurate assignment of the switching signals to the corresponding control element in conjunction with a corresponding evaluation circuit is made possible.

The particular advantage of the invention is the fact that in addition to the mechanical switching capability by means of switching element and switching contacts temporally and spatially upstream redundant switching mechanisms are provided whose function is guaranteed independent of the mechanical actuation of the control element, so that the triggered switching signals in many ways can be used, as will be explained.

The invention will be explained in more detail by exemplary embodiments. In the accompanying drawings show:

1 : a schematic sectional view of a control element according to the invention of a keyboard;

2a a schematic plan view of a plurality of juxtaposed controls a keyboard, each equipped with a light barrier;

2 B a schematic plan view of several juxtaposed controls a keyboard with a common light barrier;

2c a schematic plan view of arranged in two rows controls a keyboard, each row is equipped with a common photocell; and

3 : A schematic plan view of a control panel of a keyboard with matrix-like controls, in which all controls each one column and row are provided with a common photocell.

1 shows a schematic sectional view of a control element according to the invention 1 a keyboard, as usual on one with traces or a wiring 2 provided printed circuit board 3 is constructed. The tracks 2 point in the area of the operating element 1 two spaced-apart contact elements 4 on, by means of a movable switching element located above 5 can be bridged. As switching elements 5 All known possibilities in appropriate application come into consideration. So can the switching element 5 a metal plate or a metallized plastic plate, or there may be used snappers or carbon foils.

It is understood that the switching element 5 rests on an elastic spacer, not shown, extending over the contact elements 4 is located, wherein for the contact elements 4 Recesses are provided in the spacer, so that a contacting of the switching elements 4 is avoided at rest. The contact of the switching element 5 with the contact elements 4 is achieved by depressing the same. Alternatively, the spacer can accordingly also over the entire circuit board 3 extend.

Above this arrangement is a transparent support plate 6 , or a sufficiently stable film over the area of the switching element 5 an opening 7 having. This opening 7 gets through a thinner front foil 8th covered, which also acts as a control surface. The front foil 8th can also the entire carrier plate 6 cover.

Drawing according to the right and left of the contact elements 4 are on the circuit board 3 one optical transmitting / receiving unit each 9 . 10 , As a transmitting unit, for example, IR light-emitting diodes or IR laser diodes and customary as a receiver photodiodes into consideration. Such transmitting / receiving units can, for example, as SMD components in the control 1 be integrated with the tracks or the wiring 2 the circuit board 3 are connected.

Vertically above each transceiver 9 . 10 are outside on the carrier plate 6 each deflection prisms 10 . 11 such at a distance from each other attached that one of the transceiver units 9 upwards through the carrier plate 6 to the deflection prism 11 radiated light beam 13 by 90 ° to the opposite deflection prism 12 deflected and there by 90 ° down through the support plate 6 to the other transmitting / receiving unit 10 is distracted. In this way, the function of a light barrier as a redundant switching element in the control 1 integrated. In case of the front foil 8th the entire carrier plate 6 Covered, the deflection prisms must 19 . 11 of course on the front foil 8th to be ordered.

1 only shows the basic structure of a control unit according to the invention 1 , Practical embodiments may depart from this basic structure and function by adding more elements. Also, the mechanical switching element can be designed differently.

The deflecting prisms 11 . 12 may also be embedded in a further transparent film (not shown), which is also transparent carrier plate 6 overall covered, but over the front foil 8th is omitted, so that by pressing the control 1 the associated light barrier is interrupted.

Of course, per control element 1 It is also possible to provide a plurality of such light barriers. Thus, two or more mutually parallel photocells can be realized, for example, if they are security-related large keys. Also, two or more intersecting photocells per control element 1 be provided to achieve even greater operating safety.

By means of this additional switching element as a further redundant switching element in the form of a light barrier, it is now possible to evaluate the interruption of the light barrier as a further switching signal in a corresponding evaluation circuit.

Upon actuation of the operating element 1 Always first the light barrier must be interrupted, so that a first electronic switching signal is generated and then by pressing down the film 8th a second mechanically triggered switching signal which is generated with a time delay to the first switching signal.

As a result, different scenarios can be realized. So can a valid operation of the control 1 be allowed only when the first switching signal by interrupting the light barrier within a predetermined time interval, a mechanically generated second switching signal follows.

If the second switching signal fails, this can have two causes. First, the operator may have decided to use the control 1 but not to press, or the mechanical switch part is defective.

If the second switching signal remains off, the error can be noted in an error log and / or a warning is issued to the operator that the corresponding key may be defective.

If it is a functionally important or safety-relevant key, such as an emergency stop button, then it can also be determined that switching off the light barrier is effected either immediately or after a short delay time, the switching off of a device.

The 2a -C show examples of possible applications of the invention as a plan view of keyboards.

In 2a is keyboard with several adjacently arranged control elements according to the invention 1 a keyboard shown in which each control element 1 equipped with a photocell. Here is every control 1 be monitored in terms of its function. For the keyboards 2 B , c are each with the photocells several controls 1 monitored simultaneously.

2 B shows a keyboard with several side-by-side controls 1 , which have a common photocell.

Another variant of a keyboard goes off 2c out. Here are the controls 1 arranged in two rows next to each other, which are equipped with a common photocell extending over both rows.

A particular embodiment of a keyboard works 3 out. Here are the controls 1 arranged in a matrix in rows and columns. Each row and each column is equipped with a common photocell, covering all the controls 1 each row and column extends, in such a way that each control element 1 located at the intersection of the light beams of two photoelectric sensors. Thus, in connection with a corresponding evaluation circuit, it can be unambiguously determined by the interruption of the intersecting light beams of two light barriers which operating element has been selected by the operator.

This achieves a particularly high operating safety and a free evaluation of the switching signals and reliable triggering of the desired switching functions.

The control element according to the invention can also be used for other than the keyboards described above in a meaningful way.

LIST OF REFERENCE NUMBERS

1

 operating element

2

 Interconnect / wiring

3

 circuit board

4

 contact element

5

 switching element

6

 support plate

7

 opening

8th

 Front foil / operating surface

9

 Transmit / receive unit

10

 Transmit / receive unit

11

 deflecting prism

12

 deflecting prism

13

 beam of light

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2001033 A1 [0002]
• DE 202007006647 U1 [0004]
• DE 202007016762 U1 [0005]
• DE 20308920 U1 [0006]

Claims (10)

Control element for keyboards, comprising at least one mechanically actuable by finger pressure switching element ( 5 ), with the associated contact elements ( 4 ) on one with interconnects ( 2 ) provided printed circuit board ( 3 ) can be bridged, wherein the keyboard by a transparent support plate ( 6 ) and where above the control surface ( 8th ) of the operating element ( 1 ) at least one light barrier is arranged. Operating element according to Claim 1, characterized in that the light barrier consists of two optical transmitting / receiving units ( 9 . 10 ) next to the contact elements ( 4 ) on the circuit board ( 3 ), which via deflecting prisms ( 11 . 12 ) on the carrier plate ( 6 ) are optically interconnected. Operating element according to claim 2, characterized in that the transmitting / receiving units ( 9 . 10 ) are designed as SMD components with the wiring ( 2 ) on the circuit board ( 3 ) are electrically connected. Operating element according to claim 2 or 3, characterized in that the transceiver units ( 9 . 10 ) Contain IR light-emitting diodes or IR laser diodes. Operating element according to claim 2, characterized in that the deflecting prisms ( 11 . 12 ) on the carrier plate ( 6 ) are embedded in a transparent film, which above the control surface ( 8th ) is omitted. Operating element according to one of Claims 1 to 5, characterized in that a signal from one of the transceiver units ( 9 . 10 ) up through the carrier plate ( 6 ) to a deflection prism ( 11 . 12 ) radiated light beam ( 13 ) by 90 ° to the opposite deflection prism ( 11 . 12 ) deflected and there by 90 ° down through the support plate ( 6 ) to the other transceiver unit ( 9 . 10 ) is distracted. Use of the control element according to one of claims 1 to 6 for keyboards with control elements arranged in one or more rows ( 1 ). Use of the control element according to one of claims 1 to 7 for keyboards with a plurality of matrix-like arranged control elements ( 1 ). Use of the operating element according to one of claims 7 or 8, characterized in that a plurality of adjacent control elements ( 1 ) are covered by a common light barrier. Use of the operating element according to one of claims 7 or 8, characterized in that the operating elements ( 1 ) each row and / or column are each covered by a common light barrier.

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