WO1997044707A2

WO1997044707A2 - Liquid crystal display device with integrated solar power source and antenna

Info

Publication number: WO1997044707A2
Application number: PCT/US1997/008832
Authority: WO
Inventors: Tsutomu Takahisa; Koyo Hasegawa
Original assignee: Digital D.J. Incorporated
Priority date: 1996-05-24
Filing date: 1997-05-23
Publication date: 1997-11-27
Also published as: ID16977A; WO1997044707A3; AU3077697A

Abstract

A liquid crystal display device includes a solar power source disposed substantially underneath a liquid crystal display layer such that light incident on the liquid crystal display layer is transmitted through the liquid crystal display layer and is incident upon the solar power source. The display device further includes an antenna disposed on the liquid crystal display layer. The antenna uses conductors that do not substantially block the display or the light being transmitted through the display layer.

Description

LIQUID CRYSTAL DISPLAY DEVICE WITH INTEGRATED SOLAR POWER SOURCE AND ANTENNA

RELATED APPLICATIONS This is a continuation in part of co-pending United States patent application, serial number 08/549,655, filed October 27, 1995, which is a continuation in part of co- pending United States patent application, serial number 08/425,993, filed April 20, 1995, which is a continuation in part of United States patent application, serial number 08/045,352, filed April 8, 1993, now U.S. Patent no. 5,491,838. The contents of these applications are hereby incorporated by reference as if fully set forth herein.

BACKGROUND AND FIELD OF THE INVEN TION This invention relates generally to electronic devices, and specifically to a display device integrated with an antenna and a solar power source. Numerous modern electronic devices make use of digital displays, such as liquid crystal displays, for providing users with information. Some such displays are limited to alphanumeric readouts, while others include graphics, ranging from simple iconic representations to full-screen television video. To be of maximum usefulness to the user, these digital displays are often fairly large with respect to the remainder of the components of the electronic device.

Because liquid crystal displays require relatively little power, it has become common for electronic devices using such displays, e.g., calculators, to be powered by an array of solar cells rather than conventional batteries. Unfortunately, the current state of the art in solar cell technology generally requires use of a fairly large solar cell subsystem to power even low-drain devices such as digital clocks. Thus, the size of the device must be further increased to accommodate the solar power subsystem.

In electronic devices that transmit or receive radio-frequency signals, such as a pager or hand-held television receiver, an additional component required for operation is an antenna. Depending on the frequency of operation, conventional loop or rod antennas are included in such devices, and further increase the size of the overall device package.

Notably absent from the known prior art, however, is any device that integrates the display, antenna, and solar power subsystems so as to reduce the overall size required for the device.

It would be desirable to have an integrated display device, antenna, and solar power subsystem to permit manufacture of portable electronic devices having sizes smaller than is possible using existing components.

SUMMARY OF THE INVENTION

In accordance with the present invention, a display device includes an integrated antenna.

In another aspect of the invention, the display device includes an integrated solar power subsystem. The features and advantages described in the specification are not all-inclusive, and particularly, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims hereof.

Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an illustration of a display device (100) with integrated solar power source and antenna, in accordance with the present invention.

Figure 2 is an illustration of a different embodiment of a display device (100) with integrated solar power source and antenna, in accordance with the present invention.

Figure 3 is an illustration of still another embodiment of a display device (100) with integrated solar power source and antenna, in accordance with the present invention. Figure 4 is an illustration of yet another embodiment of a display device (100) with integrated solar power source and antenna, in accordance with the present invention.

Figure 5 is an illustration of an electronic device including a liquid crystal layer, a solar panel layer, and additional layers, in accordance with the present invention.

Figure 6 is an illustration of a circuit (600) including a semiconductor device (650) integrating a solar power portion and a MOS portion, in accordance with the present invention.

Figure 7 is a schematic diagram of the circuit illustrated in figure 6. Figure 8 is an illustration of a semiconductor device (850) integrating a solar power portion and an NPN bipolar transistor portion, in accordance with the present invention.

Figure 9 is a schematic diagram of a circuit implemented using the semiconductor device illustrated in figure 8. Figure 10 is an illustration of a semiconductor device (1050) integrating a solar power portion and a C-MOS portion, in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT The figures depict a preferred embodiment of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

Referring now to figure 1, there is shown a display device 100 in accordance with the present invention. Display device 100 is suitable for incorporation in a wide variety of electronic devices, such as portable broadcast radio and television receivers, pagers, cellular telephones, cordless telephones, and the like. Display device 100 includes a conventional liquid crystal layer 101 for provision of a digital alphanumeric or graphical display. Conventionally, such displays may be manufactured so that a good portion of the incident light 1810 falling upon liquid crystal layer 101 is transmitted through liquid crystal layer 101. Juxtaposed at the underside of liquid crystal layer 101 is a solar cell layer 102. Because liquid crystal layer 101 allows a significant amount of light to be transmitted through it, disposing solar cell layer 102 underneath liquid crystal layer 101 permits double-use of the area, or "footprint" of display device 100 — both a display function and a power source function are provided using the same footprint. It should be recognized that other types of displays could be used for liquid crystal layer 101, as long as sufficient light is able to pass through the layer and be incident upon solar cell layer 102.

Also integrated in display device 100 is a set of antenna leads, e.g., 103. In the configuration shown in figure 1, these leads are disposed on the top of liquid crystal layer 101. In one application where a loop antenna is desired, such as in reception of standard amplitude modulation broadcast signals, antenna leads similar to lead 103 are disposed on the bottom of solar cell layer 102, and the leads at the top of liquid crystal layer 101 are joined to the leads at the bottom of solar cell layer 103 by a set of antenna jumper wires, e.g., 104. In a preferred embodiment, conventional transparent conductors, such as planar epitaxial films of tin oxide (Snθ2) are used to implement antenna lead 103. In some applications, however, if display device 100 is large enough, small conventional non-transparent conductors, such as fine-gage copper wire, may also be used for antenna lead 103 without any significant degradation of either viewing ability of the display produced by liquid crystal layer 101 or the amount of light incident upon solar cell layer 102. The ends of the antenna formed by leads 103 and jumpers 104 are connected in a conventional manner to the radio frequency circuitry with which they are used.

In another embodiment of display device 100, illustrated in figure 2, magnetic material end-caps 202, 203 are disposed at the edges of device 100 to increase the efficiency of the loop antenna formed by antenna leads 103 and jumpers 104. In practice, it is found that the presence of magnetic material end-caps 202, 203 does not impact the operation of liquid crystal layer 101. It should be recognized that in one possible alternate embodiment in which display device 100 is implemented using a cathode-ray tube rather than a liquid crystal layer, conventional magnetic shielding techniques should be used to prevent the magnetic end-caps from impacting the operation of display device 100. In many modern applications such as broadcast FM and television reception, untuned wire antennas provide good results. Referring now to figure 3, yet another embodiment of display 100 includes an antenna lead 303 disposed in a serpentine fashion over the top of liquid crystal layer 101, terminating as a connector lead 304 for coupling to conventional radio frequency circuitry (not shown).

It should be noted that numerous other variations of the configurations illustrated in figures 1 - 3 could be used to implement an integrated antenna in device 100. For instance, referring now to figure 4, there is shown an embodiment of device 100 in which both antenna leads 403 and antenna jumpers 404 are disposed directly on the top and edge surfaces of liquid crystal layer 101. In this embodiment, corresponding leads to leads 403 are disposed between liquid crystal layer 101 and solar cell layer 102. Such a configuration has the advantage over that shown in figure 1 of having the loop closer to the top surface of device 100, where signal strengths may be greater, but the disadvantage of having a smaller cross-sectional loop area than the implementation shown in figure 1 and of including more conductors that may either interfere with viewing of the display produced by liquid crystal layer or transmission of light to solar cell layer 102.

It should be recognized that additional conventional circuitry, such as touch¬ screen and backlighting components, can be integrated with device 100 as well. As an example of a touch-screen implementation, a conventional touch-screen layer is placed either directly above or directly below antenna leads 103, separated from leads 103 by an isolating layer of transparent plastic or other insulating material. As an example of a backlighting implementation, a conventional backlighting component is disposed between liquid crystal layer 101 and solar cell layer 102, and is disposed in such a manner as to not block all of the incident light 1810 from solar cell layer 102. For instance, the backlighting component may be disposed only at the periphery of device 100, leaving the center portion clear for transmission of light to solar cell layer 102. Alternatively, the backlighting component may be disposed at the center portion of device 100 to leave the periphery clear for transmission of light to solar cell layer 102. In a third alternative, the backlighting component may be implemented in strips disposed across the boundary between solar cell layer 102 and liquid crystal layer 101 so that light falling between the strips can be incident upon solar cell layer 102. Still another alternative is for display 100 to be edge-lit rather than back-lit, so that illumination of the display provided by liquid crystal layer 101 is achieved without blocking any of the light incident upon solar cell layer 102.

Referring now to figure 5, there is shown a cutaway edge view of a portion of an electronic device 500. Device 500 includes a liquid crystal unit, or layer, 1801 for providing display of information as discussed herein. Underneath layer 1801, device 500 further includes a solar panel unit, or layer, 1802. Solar panel layer 1802 includes a conventional solar panel array that is used in a conventional manner to power device 500 and to recharge batteries for device 500. In typical usage, most of the display provided by liquid crystal layer 1801 remains clear rather than opaque most of the time. Thus, virtually all of any incident light 1810 falling upon liquid crystal layer 1801 also reaches solar panel layer 1802. By integrating a conventional solar panel layer 1802 with a conventional liquid crystal layer 1801, device 500 can be made physically smaller than if a solar panel unit and a liquid crystal display were disposed adjacent to one another.

In the embodiment illustrated in figure 5, a thin film transistor layer 1803 is disposed immediately below solar panel layer 1802. The remainder of the electronics comprising device 500, including LSI layer 1804 and battery layer 1805, are disposed substantially underneath the thin film transistor layer 1803. It should be recognized that variations in the arrangement of these portions of device 500 may readily be made while still obtaining the benefits of integrating a solar panel and a liquid crystal display. As an example, the thin film transistor layer 1803, as well as the LSI layer 1804 and battery layer 1805, may be located remotely from solar panel layer 1802 and liquid crystal layer 1801. Alternatively, solar panel layer 1802 may be fabricated directly on one of the components of device 500, for instance LSI layer 1804. Specifically, solar panel layer 1802 may be bonded to LSI layer 1804 or may even be constructed from the same substrate as used in LSI layer 1804, depending on requirements of maximum desired size and weight of device 500. It should be recognized that the readability of the display provided by liquid crystal layer 1801 may be affected by the color of solar panel unit 1802. Accordingly, liquid crystal layer 1801 and solar panel unit 1802 should be selected in a manner that provides reasonable contrast for typical viewing conditions.

Referring now to figure 6, there is shown an electronic circuit 600 including a cutaway edge view of a semiconductor device 650 that integrates a solar power portion 610 with a metal-oxide semiconductor (MOS) portion 620. Specifically, an N layer 612 is juxtaposed with a P layer 613 to form a conventional solar cell portion 610. The P layer 613 is also used as the top layer of a MOS portion 620. The MOS portion 620 also includes an N+ layer 624 bonded to the chassis of the equipment in which circuit 600 is disposed, and N+ layer 625, an insulator 626, and a metal layer 627 that, combined with P layer 613 implement a metal oxide semiconductor field-effect transistor. When an input source VGS 603 and resistors 601 and 602 are connected in the appropriate manner as shown, circuit 600 operates as shown in the schematic diagram of Figure 7. The solar cell portion 610 provides the source VSS 705, the MOS portion 620 implements MOS-FET 710, and the remaining components discussed above, i.e., resistors 601, 602 and VGS input source 603, are implemented conventionally. Circuit 600 is exemplary of circuitry that can be implemented by integration of a solar power source with MOS semiconductor circuitry.

Referring now to figure 8, there is shown a cutaway edge view of a semiconductor device 850 that integrates a solar power portion 810 with an NPN bipolar transistor portion 820. Specifically, an N channel semiconductor layer 812 is disposed atop a P+ layer 813, which is disposed atop a P layer 816 to implement a solar cell portion 810, with + and - terminals 814, 815, respectively.

NPN bipolar transistor portion 820 is implemented by layer 816, discussed above, as well as an epitaxial N layer 821, an embodied N- layer 822, and regions 823 - 826. P+ isolation region 823 and embodied N- layer 822 surround the other regions 824 - 826 and isolate them electrically from other circuit components implemented in other portions of epitaxial N layer 821. N+ collector region 824 implements a transistor collector, P base region 825 implements a transistor base, and N+ emitter region 826 implements a transistor emitter. Referring now to figure 9, there is shown a schematic diagram of a circuit 800 implemented in part by semiconductor 850. Specifically, solar power portion 810 provides Vcc 905; NPN bipolar transistor portion 820 provides NPN transistor 910. Resistors 901, 902 and Vbe input source 903 are implemented conventionally. Configured as shown, circuit 800 provides a common emitter amplifier and is exemplary of circuitry that can be implemented by integrating a solar power source with bipolar semiconductor circuitry. Referring now to figure 10, there is illustrated a cutaway edge view of a semiconductor 1050 that includes a solar power portion 1010 and a complementary metal-oxide semiconductor (C-MOS) portion 1020. Specifically, conventional N channel semiconductor 1012 and P+ layer 1013 implement a solar power cell that is capable of powering other circuitry via + and - terminals 1014 and 1015, respectively. Disposed underneath layers 1012 and 1013 is a conventional silicon N channel substrate 1028 on which is constructed a conventional C-MOS circuit.

The C-MOS circuit is implemented in a conventional manner, using P+ regions 1021, 1022, a P well 1023 with N+ regions 1024, 1025, and an oxide layer 1030. By the addition of conductors at the bottom of semiconductor 1050, a C-MOS with sources A and B 1026, 1027, drain 1028, and gate 1029 is provided. Configured as shown, semiconductor 1050 is exemplary of circuitry that can be implemented by integrating a solar power source with C-MOS semiconductor circuitry.

One particular advantage of integration of various components as described herein is that circuits can be formed in a manner that is more flexible and that conforms to more form factors, than would be possible by simply connecting, for instance, a discrete solar cell with a discrete amplifier circuit on a conventional circuit board.

Integration of the various circuits and devices illustrated and discussed herein may be accomplished using conventional semiconductor techniques (e.g., diffusion, ion injection). Further background on the fabrication of semiconductors as discussed herein is available through numerous texts, examples of which include Jacob Millman, MICROELECTRONICS: DIGITAL AND ANALOG CIRCUITS AND SYSTEMS (McGraw Hill, 1979); Donald L. Schilling, et al., ELECTRONIC CIRCUITS: DISCRETE AND INTEGRATED (McGraw Hill, 1979); and David Casasent, DIGITAL ELECTRONICS (Quantum Publishers, Inc., 1974). From the above description, it will be apparent that the invention disclosed herein provides a novel and advantageous display device with integrated solar power source and antenna. The foregoing discussion discloses and describes merely exemplary methods and embodiments of the present invention. As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

Claims

What is claimed is:

1. A display device, comprising: a first subsystem providing a data display, the first system being disposed so as to be subject to incident light on a top portion of the first subsystem, the first subsystem being at least partially transparent so as to allow said incident light to be transmitted through the first subsystem to a bottom portion thereof; and a second subsystem, disposed substantially underneath said bottom portion of said first subsystem so as to be subject to said incident light transmitted through the first subsystem, the second system generating electricity responsive to said incident light.

2. A display device as set forth in claim 1, further comprising an antenna subsystem disposed at least in part over said top portion of said first subsystem.

3. A display device as set forth in claim 1, further comprising a semiconductor circuit subsystem disposed substantially underneath said second subsystem.

4. A display device, comprising: a first subsystem providing a data display, the first system being disposed so as to be subject to incident light on a top portion of the first subsystem, the first subsystem being at least partially transparent so as to allow said incident light to be transmitted through the first subsystem to a bottom portion thereof; and an antenna subsystem disposed at least in part over said top portion of said first subsystem.

5. A display device as set forth in claim 4, further comprising a semiconductor circuit subsystem disposed substantially underneath said second subsystem.

6. A display device as set forth in claim 4, wherein the antenna subsystem forms a loop antenna.

7. A display device as set forth in claim 4, wherein the antenna subsystem includes a conductor that is substantially transparent.

8. A display device as set forth in claim 4, wherein the antenna subsystem includes a conductor that does not substantially interfere with transmission of light through said first subsystem.

9. A method of implementing a display device, comprising: forming a display layer for data display, the display layer being at least partially transparent; forming a solar power source layer; and disposing said solar power source layer underneath said display layer, such that light incident upon said display layer is transmitted through said display layer and is incident upon said power source layer.

10. A method as in claim 9, further comprising integrating an antenna circuit with said display device.

11. A method of implementing an electronic circuit using semiconductor material, comprising integrating a solar power source layer and a transistor circuit layer by forming a solar power source layer using a first portion of the semiconductor material and forming a transistor circuit layer using a second portion of the semiconductor material.

12. A method as in claim 11, wherein the first portion and the second portion are mutually exclusive.

13. A method as in claim 11, wherein the first portion and the second portion have in common a third portion of the semiconductor material.

14. An electronic circuit implemented using semiconductor material, comprising: a solar power source layer implemented by a first portion of the semiconductor material; and a transistor circuit layer implemented by a second portion of the semiconductor material.

15. An electronic circuit as in claim 14, wherein the first portion and the second portion are mutually exclusive.

16. An electronic circuit as in claim 14, wherein the first portion and the second portion have in common a third portion of the semiconductor material.