Instrument with key-activated touch pad

Abstract

 An electronic instrument (10) includes a housing (12) having an interface panel (14). The interface panel includes a touch panel (20), and a number of button elements (36) are positioned over the touch panel. Each button has one part (50) adjacent to the touch panel, and an exposed surface, so that the exposed surface may be pressed by a user to contact the touch panel, and to generate a signal to the circuitry of the instrument identifying the button that was pressed based on its position on the touch panel. The touch panel may have an exposed portion (66) providing a cursor control device, or be a transparent screen overlay positioned over a display screen (22) for selecting displayed elements.

Description

Field of the Invention

[0001] The invention relates to electronic instrument control panels, and more particularly to touch sensitive controls.

Background and Summary of the Invention

[0002] Many electronic instruments and devices require interfaces for the entry and display of information by and to a user. An instrument may have a display screen, a set of buttons, and a cursor control device, each using different technology. The display screen may include a touch screen overlay that allows the user to touch a point on the screen to select an element displayed at that point, to indicate a desired position, or for any other purpose for which a cursor might be controlled.

[0003] Other cursor control devices such as touch pads used on some notebook computers use a small pad on which the user positions or slides a fingertip to position and move a cursor on a display screen. In contrast to the touch screen, which uses the absolute position of contact to correspond to a screen position, a touch pad provides relative motion, and the pad is simply an analog of the screen or a portion of the screen.

[0004] For regularly used functions on an instrument, dedicated buttons are used. These are generally permanently labeled for readability, and operate individual electronic switches connected to instrument circuitry. The keyboard of a notebook computer, the front panel of a test and measurement instrument, and the controls of a hand-held personal digital assistant (PDA) are all applications for dedicated buttons to supplement display screens and other cursor control devices.

[0005] Button controls require custom-designed hardware for each application, with a printed circuit supporting soldered switches located in positions corresponding to each button. Metal shielding may be provided with limited cutouts for each button. In critical applications, the electrical performance characteristics of these components must be analyzed and characterized, such as to ensure that EMI/EFI are within acceptable limits. For different models of similar instruments, components must be separately designed and constructed. This slows prototyping efforts, and increases costs. Even a minor difference between similar models affecting only the number or position of buttons on the panel requires a wholesale redesign, and stocking of different circuit components for each model.

[0006] The embodiments disclosed herein overcome these limitations by providing an electronic instrument includes a housing having an interface panel. The interface panel including a touch panel, and a number of button elements are positioned over the touch panel. Each button has one part adjacent to the touch panel, and an exposed surface, so that the exposed surface may be pressed by a user to contact the touch panel, and to generate a signal to the circuitry of the instrument identifying the button that was pressed based on its position on the touch panel. The touch panel may have an exposed portion providing a cursor control device, or a transparent screen overlay positioned over a display screen for selecting displayed elements.

Brief Description of the Drawings

[0007] 

Figure 1 is an exploded view of an instrument according to a preferred embodiment of the invention.

Figure 2 is a sectional view of the instrument of Fig. 1.

Figure 3 is a perspective view of an instrument according to an alternative embodiment of the invention.

Figure 4 is a sectional view of an instrument panel according to an alternative embodiment of the invention.

Detailed Description of a Preferred Embodiment

[0008] Figure 1 shows an electronic instrument 10 having a housing 12 and a bezel 14 providing a lid for the housing. Within the housing are contained an elastomeric key or button sheet 16, a touch sensitive pad 20, a liquid crystal display 22, and a circuit board 24 connected to the touch pad and to the display for receiving and processing signals from the touch pad, and for driving the display, among other operational functions of the device. Other components not required to illustrate the concept of the invention are omitted for clarity. These include spacers, structural supports, power supply, illumination, and other circuitry.

[0009] The bezel 14 has a button portion 26 and display portion 30. The button portion defines a plurality of small apertures 32 arranged in a pattern spaced apart adequately to permit selective actuation by an adult finger tip. The display portion 30 defines a single large display aperture 34. The key pad sheet 16 includes a set of protruding buttons 36, each sized to be closely received in a corresponding aperture 32, and to slightly protrude from the front surface of the bezel. As will be shown below, a protrusion on the opposite side of each button (on the rear of the sheet) serves to provide an enhanced-pressure contact with the touch pad. Each button is integrally connected to a flexible sheet 40. In some embodiments, each button may be imprinted or molded with indicia of the button's function. In the illustrated embodiment, indicia are printed on the bezel, adjacent to the button apertures.

[0010] The touch pad 20 extends essentially the entire area of the device, fully underlying the display aperture 34 and the region below all the buttons. The touch pad is transparent in the preferred embodiment, so that the display may be viewed through it. The touch pad may use any conventional touch pad technology suitable for actuation with a fingertip, stylus or other implement. It should have adequately fine resolution to permit small gradations of position on the display to be resolved. In the preferred embodiment, with buttons spaced apart by at least about 1.0 cm, the resolution is preferably 1.0 mm or finer. The display is a conventional LCD device, or may be any other display technology.

[0011] Figure 2 shows the button sheet 46 having protrusions 50 protruding below each button and abutting the touch pad 22. The touch pad has a pressure sensitivity so that the weight of the button sheet does not actuate the pad, but so that a comfortable key strike pressure readily actuates the pad to send a signal to the circuitry indicating the location of the contact. Not shown in Figure 2 is a support surface behind the touch pad to provide a solid, flat backing to generate compression of the touch pad at the point where a button protrusion contacts the pad.

[0012] Figure 3 shows an electronic test and measurement instrument having a display 62, a control panel 64, and a touch pad cursor control 66. In this embodiment, a touch sensitive pad 70 underlies the entire control panel and touch pad, but does not overlay the display. The portion under the control panel is configured to transmit to connected circuitry the absolute location of pressure. In the manner discussed above, the circuitry compares the location where pressure is detected with an assigned command or function associated in software with the button or switch at that location, and performs the desired function. This is an absolute location mapping arrangement.

[0013] For the cursor control pad 66, a portion of the pad 70 is exposed, so that a user's fingertip may touch or drag across the pad to control position and movement of a cursor 72 on the screen. As in conventional cursor control pad such as used on notebook computers, the cursor's position does not absolutely correspond to the location of the finger on the pad. The cursor location is based on relative movement of the finger, regardless of where the fingertip first makes contact. Thus, a cursor near the upper right of the screen may be moved further to the upper right by touching the pad at the lower left (or any position), and dragging a fingertip to the upper right. Long movements may be made by multiple sweeps of the fingertip, and the pad may be programmed to move a different acceleration rates based on the input movement rate, in the manner of conventional mouse control software for personal computers.

[0014] Regardless of touch pad programming features, the pad portion operates in a different mode than does the portion behind the control panel. This allows the use of a single component pad 70, with the control software or pad elements configured for the particular application.

[0015] In an alternative variation of the device, the touch panel may extend in front of the display, offering additional absolute cursor control, and for operation of displayed "soft" buttons on the screen.

[0016] Figure 4 shows another alternative embodiment, in which an instrument 80 has a display screen 82 that underlies not just the display aperture 34, but also a set of small apertures 84, each associated and adjacent to a button 36. The small apertures are not intended for touch screen access, but serve as windows to display changeable legends or nomenclature for each button. The legends may change in a given device depending on operations, such as a consumer electronics remote control that displays different functions depending on which device is being controlled. The changes may also be made between different products, so that a common chassis may be used for different applications, with only software changes needed to make the device adaptable to a new use.

[0017] While the above is discussed in terms of preferred and alternative embodiments, the claims are not intended to be so limited. The button activated touch pad may be operated by other switches that contact a touch pad under pressure. For instance, a toggle switch having two rear protrusions may apply pressure to the touch panel at different locations depending which way the switch is toggled. A joystick having a ring of at least three protrusions may indicate the direction of pressure. A rotary knob having at least one protrusion constantly biased against the pad may indicate dial position by the location of the pressure along a path it sweeps. Other switches may indicate different degrees of pressure, such as by a protrusion that compresses to a different diameter contact spot under greater pressure, so that the pad may register the size of the pressure spot.

Claims

1. An electronic interface panel (10) comprising:

a bezel (14) defining a first aperture (32);

a button (36) at least in part occupying the first aperture;

a touch panel (20), at least a portion of which is overlaid by the bezel;

a first portion of the touch panel abutting the button; and

a second portion of the touch panel revealed by the bezel.

2. A panel according to claim 1 wherein the bezel defines a second aperture (34), and wherein the second aperture is registered with the second portion of the touch panel.

3. A panel according to claim 1 or claim 2 wherein the second portion of the touch panel is a cursor control device.

4. A panel according to any one of claims 1 to 3 including a display device (22) coextensive with at least a portion of the second portion of the touch panel.

5. A panel according to any one of claims 1 to 4 including a plurality of buttons (36), each occupying a separate aperture, and each contacting a portion of the touch panel.

6. An electronic instrument (10) comprising:

a housing (12) having an interface panel (14);

the interface panel including a touch panel (20);

a plurality of button elements (36) positioned over a first portion of the touch panel;

each button having a first button surface (50) adjacent to the touch panel, and a second exposed surface, such that the exposed surface may be pressed to bias the first button surface against the touch panel; and

the touch panel having an exposed second portion.

7. An instrument according to claim 6 including a bezel (14) overlaying the touch panel and having apertures receiving the buttons.

8. An instrument according to claim 6 or claim 7 including a display device (22) coextensive with at least a portion of the second portion of the touch panel.

9. An instrument according to any one of claims 6 to 8 including a display device (22) associated with the second portion of the touch panel.

10. An instrument according to any one of claims 6 to 9 wherein the touch panel (20) is trans-visible.

11. An input device comprising a touch pad having a first area which is exposed to permit a user to input information by touching various locations within the area, and a second area underlying contact means operable by the user to contact the second area at a predetermined location therein to input other information.

Drawing