PEANA DANIEL (US)
CANTAVE HERVE JOSEPH (US)
WASKO KENNETH M (US)
| US4104627A | 1978-08-01 | |||
| US4876537A | 1989-10-24 |
| 1. | A method comprising the steps of. polarizing ambient light to provide a polarized light; rotating the plane of polarization of selected portions of the polarized light to provide rotated portions and unrotated portions of the polarized light; substantially absorbing the rotated portions; and generating an electrical signal in response to the unrotated portions, wherein at least some of the illumination of the unrotated portions is reflected so that the contrast between the rotated portions and the unrotated portions provides a message. |
| 2. | The method according to claim 1 wherein the rotating step comprises the step of generating an electrical field in the selected portions of the polarized light. |
| 3. | The method according to claim 1 wherein the absorbing step comprises the step of polarizing the rotated portions and unrotated portions. |
| 4. | The method according to claim 1 wherein the generating step comprises the step of sensing the magnitude of the ambient light. |
| 5. | The method according to claim 1 wherein the generating step comprises the step of providing an energy source for driving said rotating step. |
| 6. | The method according to claim 1 wherein the rotating step and the generating step occur in a sequentially pulsating first and second state, respectively. |
| 7. | An information display apparatus comprising: first means for providing information by the contrast of absorbed and unabsorbed ambient light; and second means for generating an electrical signal in response to the unabsorbed ambient light passing through said first means. |
| 8. | The apparatus according to claim 7 wherein said first means is a liquid crystal display. |
| 9. | The apparatus according to claim 8 wherein said second means is a solar cell. |
| 10. | The apparatus according to claim 7 wherein said second means is a solar cell. |
| 11. | The apparatus according to claim 7 wherein said second means is a solar cell contiguous to the first means so that the electrical signal is generated by the ambient light after it passes through the first means. |
| 12. | The method according to claim 7 wherein said second means comprises third means for sensing the magnitude of the ambient light. |
| 13. | The method according to claim 7 wherein said second means comprises second means for providing an energy source for driving an electronic device. |
| 14. | A selective call receiver for displaying a message, comprising: first means for receiving said message; second means for polarizing ambient light to provide a first polarized light; third means for rotating the plane of polarization of selected portions of the first polarized light in response to said first means to provide a second polarized light; fourth means for polarizing the second polarized light to provide a third polarized light, wherein the rotated selected portions of the first polarized light are substantially absorbed; and fifth means for generating an electrical signal in response to the third polarized li ir wherein the third polarized light is at least partially reflected so as to provide said message. |
| 15. | The apparatus according to claim 14 wherein said fifth means is a solar cell. |
| 16. | The apparatus according to claim 14 wherein said fifth means is a solar cell contiguous to the fourth means so that the electrical signal is generated by the third polarized light after it passes through the third means. |
| 17. | The apparatus according to claim 14 wherein said fifth means comprises sixth means for sensing the magnitude of the ambient light. |
| 18. | The apparatus according to claim 14 wherein said fifth means comprises sixth means for providing an energy source for driving said selective call receiver. |
| 19. | The apparatus according to claim 18 wherein said fifth means is a solar cell. |
| 20. | The apparatus according to claim 14 wherein said third means pulsates in a first and second state, said third means rotating said selected portions during said first state, and said fifth means generating said electrical signal during said second state. |
Field of the Invention
This invention relates in general to electronic devices having a display for providing information and a solar cell as an energy source, and more particularly, to an electronic device wherein the display and solar cell occupy substantially the same surface area in a "piggyback" fashion.
Background of the Invention
Visual displays utilizing ambient light for providing information have been used in various types of electronic devices such as calculators, watches, and selective call receivers, including pagers. The visual display may, for example, be a liquid crystal display (LCD). Likewise, solar cells have been used on these various types of electronic devices for providing voltage to the electronic components thereof from ambient light.
Typically, both the LCD and solar cell are relative large, thereby consuming a large portion of the surface area of the electronic device. This space limitation is increasingly undesirable as the electronic devices decrease in size in order to satisfy consumer desires.
Thus, what is needed is an electronic device wherein the display and solar cell occupy substantially the same surface area.
Summary of the Invention
Accordingly, it is an object of the present invention to provide a combined display and solar cell. In carrying out the above and other objects of the invention in one form, there is provided an apparatus including a display providing a message by the contrast of absorbed and unabsorbed ambient light and a light sensitive device generating an electrical signal in response to th.2 unabsorbed ambient light passing through the display. The above and other objects, features, and advantages of the present invention will be better understood from the following detailed description taken in conjunction with the accompanying drawings.
Brief Description of the Drawing
FIG. 1 is a top view of a selective call receiver having the present invention incorporated therein.
FIG.2 is a cross sectional view of a preferred embodiment of the present invention.
FIG.3 is a cross sectional view of a second embodiment of the present invention. FIG 4 is a cross sectional view of a third embodiment of the present invention.
Detailed Description of the Invention
Referring to FIG. 1, the selective call receiver in accordance with the preferred embodiment comprises a housing 11 including control buttons 12 protruding through the slots 13 in front plate 14. A display device 15, such as an LCD screen, protrudes through a slot 16 in the front plate 14. The display device 15 overlies a solar cell which is visiable through the display device 15 as may be more readily seen by referring to FIG 2.
Referring to FIG.2 taken along the lines 10-10 of FIG.l, electrodes 17 and 18 are substantially parallel and spaced apart by spacer 19. Liquid crystal molecules occupy the chamber 21 bounded by electrodes 17 and 18 and spacer 19. Polarizers 22 and 23 are contigious to electrodes 17 and 18, respectively. These elements comprise a liquid crystal display (LCD) in a manner well known to those skilled in the art.
In accordance with the present invention, a substrate 24, typically manufactured of glass or plastic, underlies the polarizer 23 and overlies a layer 25 of tin dioxide (Sn02). A "p" type layer 26 of silicon oxide (SiO) is formed over T and "n" layers 27 and 28, respectively, of silicon (Si). The layers 27 and 28 are preferrably formed of amorphous structure for increasing the reflection of the incident light, thereby improving the contrast of the LCD. A contact layer 29 is contigious to layer 28.
In operation, ambient light enters and passes through the polarizer 22 creating a polarized light. This polarized light passes through the substrate 17 and selected portions are rotated by selected liquid crystal molecules in chamber 21. Both the rotated and unrotated polarized light
pass through the substrate 18 to the polarizer 23, wherein the rotated portions are absorbed.
The unrotated polarized light passes through substrate 24 and layer 25 to the "p-i-n" layers 26, 27, and 28. The "p" type layer 26 is doped with atoms that contain one less valence electron than silicon. The "n" type layer 28 is doped with atoms having one more electron than the silicon atoms. The "i" type layer is undĪped. Excess electrons on the "n" side will move across the junction to fill vacant sites on the "p" side, which gives the "p" region a net negative charge. Excess (positive) holes move in the opposite direction, making the "n" side positively charged. The resulting charge imbalance creates an electric potential across the device. When electrons in the "i" layer intercept incoming light and become mobile, they move toward the "n" side. The electrical contact 29 draws off these electrons as a signal representive of the ambient light. The unrotated polarized light that is not absorbed by the "p-i-n" layers 26, 27, and 28 is reflected back through the display device 15 in the opposite direction, creating areas of reflected light and unreflected (absorbed) light that provides information in the form of characters or figures in accordance with the selected liquid crystal molecules. Referring to FIGs.3 and 4, second and third embodiments, respectively, comprise backlighting diffusers 31 and 32, respectively, placed between the polarizer 23 and the substrate 24. Additionally, backlighting optionally may be applied directly to the substrate 24 as shown in FIG. 1. The backlighting provides additional contrast for viewing the liquid crystal display 15. The backlighting, for an LED for example, may be pulsed "on" in a first state and "off in a second state. The solar cell would be pulsed "on" to receive the unrotated polarized light during the second state. This pulsating between first and second states would occur at a rate that in unperceivable by the human eye. By now it should be appreciated that there has been provided an apparatus including a display providing a message by the contrast of absorbed and unabsorbed ambient light and a light sensitive device generating an electrical signal in response to the unabsorbed ambient light passing through the display.