GB2354738A

GB2354738A - Backlit illumination of an individual button of a mobile phone keypad by interposing a lighting panel tab between the key actuator and a dome switch

Info

Publication number: GB2354738A
Application number: GB0023841A
Authority: GB
Inventors: Sang Y Oh; Nathan M Connell; Karen C Larson
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 1999-09-30
Filing date: 2000-09-28
Publication date: 2001-04-04
Anticipated expiration: 2020-09-28
Also published as: AR025932A1; GB0023841D0; DE10049219B4; FR2799329A1; KR100385664B1; KR20010050762A; GB2354738B; DE10049219A1; BR0004544A; JP2001148213A; CN1291060A; MXPA00009452A

Abstract

A keypad 148 (Fig.4) includes a button 150 illuminated by an electroluminescent (EL) lighting panel 142 located below the keypad. The panel is selectively illuminated and corresponds directly to each button of the keypad. A dome switch 136 is engagable by an actuator 158 of the button and is located below the panel to provide tactile feedback to a user. A tab 144 (Fig.5), which comprises an arc 162 formed by a void 160 in the panel, is located between the actuator and the dome switch and corresponds to the location of the button. The void allows the tab to move freely in a vertical direction as the button activates the dome switch. A circuitry layer (132,Fig.3) located directly below the dome switch comprises switch circuitry activated therefrom. The keypad may include audio circuitry to generate an audible user feedback tone of a unique sound corresponding to the particular function of a depressed dome switch.

Description

1 2354738 METHOD AND APPARATUS FOR ILLUMINATION OF A DATA ENTRY DEVICE

BACKGROUND OF TBE INVENTION

The present invention relates generally to the illumination of a data entry button in a data entry device. More particularly, the present invention relates to illumination by material that allows activation of a switch by the data entry button while providing illumination thereto.

The illumination of data entry buttons allows the user to visually identify an appropriate button located within a plurality of buttons in low or zero light conditions. An array of buttons grouped together is typically referred to as a keypad and the buttons within the keypad provide a io means for activating a switch on a printed circuit board (PCB) to provide a corresponding electrical signal thereby translating mechanical movement by a user to an electrical signal. Located on the top of the buttons, visible to the user, are unique identification markings corresponding to specific functions or numeric representations. Each button can be illuminated from the back or backlit to allow the user to identify the key in low or zero light conditions. The identification markings are generally centered on the button and are translucent to allow illumination via the backlighting.

One common method for providing backlit illumination is the use of a light emitting diode (LED) located on the PCB near at least one corresponding button on the keypad. The LED, when activated, provides colored backlit illumination to the identification markings on the button via the translucent material of the button. One LED may provide illumination to several adjacently located translucent buttons. To increase the consistency of illumination from button to button more LEDs may be used. This, however adds cost as well as manufacturing complexity to the product.

A thin panel lighting means such as an electroluminescent (EQ panel may also be used to provide back lighting to the data entry buttons. While the EL panel substantially blankets the PCB and the circuitry contained therein, it can be selectively illuminated in areas corresponding to each data entry button in the keypad. This provides an improved illumination distribution from button to button as each button retains its own illumination source and as a result improves readability and ease of use. However the introduction of the EL panel between the PCB and the data entry buttons introduces additional thickness and may require modification to the existing components which comprise the data entry asse mbly, potentially increasing the device size. Increasing the size of the unit is in direct contention with the desirable trend to reduce product size in many data entry devices such as portable electronic devices. Another issue is that the increased thickness may prevent the data entry button from extending downward sufficiently as it activates the switch to provide the user with feedback indicating the function has been successfully activated.

One method essentially eliminating the increase in thickness with the use of EL panels while allowing user feedback to be present is to provide holes in the EL panel corresponding to each data entry button which allows the actuator to directly engage the switch on the PCB. However because the EL material directly beneath the data entry button is now removed, the illumination distribution is less consistent from button to button, which in turn reduces the ease of use.

Accordingly there is a need to improve the method and apparatus for providing flexible and cost effective means for providing illumination and allow for switch activation in restricted areas such as portable hand held communications devices which continue to experience decreasing size requirements driven by the consumer.

BRIEF DESCRIPTION OF TBE DRAWINGS

FIG. I is a block diagram of circuitry for a wireless communication device incorporating the present invention.

FIG. 2 is a flowchart for the operation of a data entry device for the wireless communication device of FIG. I showing the activation of the electroluminescent lighting means in accordance with the present invention.

FIG. 3 is an exploded view of the data entry portion of the wireless communication device of FIG. I in accordance with the present invention.

FIG. 4 is a cross section view of the data entry portion of FIG. 3 including the PCB, the dome switch layer, the electroluminescent layer, the keypad, and the housing in accordance with the present invention.

FIG. 5 is a top view of the electroluminescent layer of FIG. 4 showing the tab in accordance with the present invention, DESCRIPTION OF THE PREFERRED EMBODIIffiNT

The present invention provides a novel method and apparatus for illuminating a button on a data entry device so that the button may be easily identified in a plurality of buttons in minimal or complete absence of ambient light while providing tactile feedback to the user. In the preferred embodiment, the tactile feedback works in conjunction with a unique audible tone simultaneously sounded as long as a button is depressed. The unique tone may be similar to that of tones typically heard when dialing a touch tone phone associating a different tone with each button. The 2 combination of these two elements alerts the user that the button has been sufficiently depressed and the desired function has been completed. The present invention significantly improves the illumination of the button via back lighting without altering the feedback characteristics. Both the tactile feedback and the unique audible tone provide the user with complete verification that the desired outcome has been achieved.

Turning now to FIG. 1, a block diagram of a wireless communication device such as a cellular radiotelephone incorporating the present invention is shown. In the preferred embodiment, a frame generator ASIC 101, such as a CMOS ASIC available from Motorola, Inc. and a microprocessor 103, such as a 68HC1 I microprocessor also available from Motorola, Inc., combine lo to generate the necessary communication protocol for operating in a cellular system.

Microprocessor 103 uses memory 104 comprising RAM 105, EEPROM 107, and ROM 109, preferably consolidated in one package 111, to execute the steps necessary to generate the protocol and to perform other functions for the wireless communication device, such as writing to a display 113, accepting information from a keypad 115, activating illumination for the keypad and display with an electroluminescent thin layer lighting means (EL panel) 116 according to the present invention, or controlling a frequency synthesizer 125. ASIC 101 processes audio transformed by audio circuitry 119 from a microphone 1.17 and to a speaker 121.

A transceiver processes the radio frequency signals. In particular, a transmitter 123 transmits through an antenna 129 using carrier frequencies produced by a frequency synthesizer 125.

Information received by the communication device's antenna 129 enters the receiver 127 that demodulates the symbols using the carrier frequencies from frequency synthesizer 125. The communication device may optionally include a message receiver and storage device 130 including digital signal processing means. The message receiver and storage device could be, for example, a digital answering machine or a paging receiver.

In the present embodiment the microprocessor 103 is used to control the user interface. In general the user interface of the communication device comprises a data entry portion and a display 113 for providing information to the user. The data entry portion of the wireless communication device 100 comprises the keypad 115, and the EL panel 116. The microprocessor 103 controls the EL panel 116, a thin layered panel lighting means such as EL panels available from the Durel 'Corporation, Chandler Arizona. The EL panel 116 provides improved illumination to both the keypad 115 and the display 113 when called upon by the microprocessor, typically in at least the 3 following situations: when the wireless communication device is turned on, when an illumination switch is activated, when a button from the keypad is depressed, or when an incoming call is first initiated.

The incorporation of the present invention into the EL panel allows the improved backlightina and retention of the tactile feedback to be realized without making changes to the existing design.

The EL panel can be as thin as 0.25mm including the adhesive layer. This thin layer characteristic allows the technology to be easily integrated into hand held and wearable portable electronic devices such as in the present invention. The capability to incorporate voids and form unique patterns in the EL material in conjunction with the ability to selectively light appropriate portions and more io specifically to light portions directly beneath the translucent button advantageously reduces the variation in illumination intensity from button to button. At the same time, selectively placing voids to form tabs in the EL material such that they accommodate the keypad buttons allows for the tactile feedback to be present.

The preferred embodiment also comprises an audible tone activated by the dome switch 136 having a unique sound corresponding to a particular function processed by the microprocessor 103.

A user may request a particular function by depressing the button 150 in the keypad 148. Depressing the button 150 activates the dome switch 136, providing tactile feedback and sending a signal to the microprocessor 103 by activating switch circuitry 132. Microprocessor 103 activates the unique audible tone corresponding to the depressed button 150. This audible tone provides additional feedback to the user in conjunction with the tactile feedback, both of which are provided when the dome switch 136 is depressed.

FIG 2 shows a flowchart of the operation of a data entry device, such as a portable communications device, incorporating the present invention. The EL panel 142 is activated under several conditions but not limited to when the device is turned on 168, when an illumination switch is depressed 172, when a button from the keypad is depressed 174, or when an incoming call is first initiated 170. From any one of these events occurring, it is then determined whether the EL panel is already illuminated. 176, 180. If the EL panel is not illuminated then the panel is activated, 178, 182. In the case of the keypad button being activated 174, the EL panel 142 is illuminated and the audible tone is activated both of which provide user feedback to acknowledge sufficient depression 30 of the button 105 to activate dome switch 136.

4 FIG. 3 illustrates an exploded view of the data entry portion of the wireless communication device 100 in accordance with the prefer-red embodiment of the present invention. The PCB 130 contains circuitry some of which is specific to the keypad 115 and the display 113. In the preferred embodiment the display is affixed to the PCB 130 by a preformed plastic bracket 140. Located directly on top of the PCB 130 is a dome switch layer 134 such as those available from Lucas Control Systems, Loveland Colorado. The dome switch layer 134 is constructed of mylarprid attached by adhesive means to the PCB 130. A plurality of dome switches, arranged in an array, correspond exactly to the button locations on the keypad layer 148. Each dome switch 136 has a conductive material on the side facing the PCB and aligns with switch circuitry 132 on the PCB 130 io such that when the dome switch 136 is depressed downward it makes contact with the switch circuitry 132, closing the switch and making an electrical connection.

The keypad layer 148 of the preferred embodiment comprises a plurality of buttons conformed into an integral, malleable keypad, each button raised and hollowed wherein the hollowed portion comprises a translucent pill 152 and a protruding member 158 formed therefrom, The translucent pill transmits the light from the EL Panel tab 144 to unique marking on the user side of the button. The protruding memberl.58 of the pill 152 extends toward the EL panel tab 144 and the dome switch 136 such that the pill 152 provides an actuator means thereto. The user side of the button comprises opaque and translucent portions, the combination thereof forming the unique markings of each button.

FIG. 4 shows a cross section of the data entry device of the preferred embodiment comprising the PCB, the dome switch layer 134, the EL panel 142, the keypad arTay148, and the housing 154.

Button 150 comprises a translucent pill 152, a member 158 protruding therefrom, and unique markings located on top of each button. The pill 152, including the protruding member 158 forms an actuator portion located adjacent to the EL panel tab 144. As the button 150 is depressed downward the EL panel tab 144 is also forced downward. The size of the EL panel tab and a void in the EL panel 142 forming the EL panel tab 144 are large enough so that the button 150 will not be hindered by the main portion of the EL panel 142 as it is urged toward the PCB 130. With the EL panel tab located directly beneath the pill 152 with the protruded member 158, backlighting of the button 150 is direct, significantly improving illumination consistency from button to button. The size of the EL panel tab 144 is dependent upon the size of the button 150. The surface area of the EL panel tab 144 should be large enough to provide ample lighting to the button 150 yet remain within the diameter of the button 150. The EL panel tab 144 is comprised of an arc 162 formed by the void 160 in the EL panel 142. The void physically forms the tab giving it mobility in the vertical direction. FIG. 5 shows the EL panel 142 of the preferred embodiment with the EL panel tab 144 formed therein such that the tab remains affixed to the EL panel 142 by a minimum distance, preferably no less than one half the diameter of the EL panel tab. The EL panel tab 144 remains attached to the EL panel 142 through the minimum distance at tab attachment point 164. The EL panel tab 144 is physically formed by the void 160 in the EL panel 142. The void 160 is formed by arc 162 such that the outer portion of arc 162 surrounds dome switch 136 and is greater than the diameter of the io button 150. The size of the arc is shown by arc measurement 166. The EL panel tab 144 substantially covers the dome switch 136. This portion of the EL panel 142 is a light producing portion providing direct lighting means to the translucent button 150 located directly above the EL panel tab 144. In order to allow the button to move unhindered as it is depressed, the outer diameter of arc 162 must be greater than button 150. This allows for button 150 to recede below the plane of the EL panel 142 and provide the tactile user feedback.

The present method and apparatus finds particular application in illundnating user data entry buttons with a thin layered illumination material which is formable to the user's needs. Current uses of thin panel lighting means improves the capacity to provide the user with tactile feedback but light distribution is not improved to it fullest potential. The current invention improves the light distribution further while maintaining the presence of tactile feedback. The formation of the tab in the thin panel lighting means allows for unrestricted movement of the button in the activation of the dome switch.

A cost effective means to provide the desired outcome is provided by the present invention where the translucent button is directly backlit while maintaining user feedback of the button. The present invention significantly improves conventional means in the field as the modifications do not require any design changes to the existing product.

While the particular embodiment of the present invention have been disclosed herein, it should be understood that the invention is not limited thereto since modification may be made by those skilled in the art. There are numerous applications where illumination of data entry buttons is necessary within unlimited number of electronic devices hand held or not.

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Claims

WE CLAIM

1. A portable electronic comi-nunication device having a data entry portion comprising:

a) at least one button for receiving user input; b) an actuator coupled to said button; c) a dome switch located adjacent to said button and coupled to said actuator for converting the user input to an electrical signal in response to movement of said actuator; and d) a thin layered panel lighting means having a tab formed therein, wherein said tab is located between said actuator and said dome switch.

2. The portable electronic communication device of claim 1 wherein said panel lighting means includes a void to form said tab.

3. The portable electronic communication device of claim 2 wherein said void is formed by an arc.

4. The portable electronic communication device of claim 3 wherein said arc defines the shape of the tab such that the tab covers said dome switch but for a connecting portion at 20 least one half the width of the tab, said portion affixing the tab to the lighting panel means.

5. The portable electronic communication device of claim I wherein said tab is affixed to the panel lighting means by a portion having a distance of at least one half the width of the tab. 25

6. The portable electronic communication device of claim 1 wherein said tab size is substantially the same geometry as said button. 7. The portable electronic communication device of claim I wherein said panel lighting 30- means is made of electroluminescent material.

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8. The portable electronic communication device of claim I having audio circuitry for generating an audible user feedback tone upon activation of the data entry button.

9. The portable electronic communication device of claim I wherein said dome switch provides tactile user feedback to the user when said button is depressed.

10. The portable electronic communication device of claim 1 wherein said actuator transmits light, emitted by said tab, to said button for illuminating an indicia thereon.

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