Patent Application
20100103332
The present invention is related generally to projectors of optical images, and, more particularly, to optical-image projectors subject to space or power-consumption limitations.
A trend in personal portable devices (such as cell phones and personal digital assistants) is to add new features while keeping the devices small. Many of these new features display information visually. For example, a high-resolution, easy-to-read display screen is provided to support photograph sharing and video downloading. Many devices also include a separate, smaller or lower-resolution display screen on the outside of the device for status messages.
In addition to these display screens on the device itself, some devices may soon incorporate a “microprojector.” Here, an image, either still or moving, is projected from the device onto a convenient surface (e.g., a projection screen or an office wall). The maximum size of the image is then effectively constrained only by the amount of available wall space rather than by the size of the device itself. Using a microprojector-equipped device, several people can simultaneously view a photograph, for example, or review a full page of text, neither of which can be readily done with even the largest displays on current personal portable devices.
Useful as these multiple display screens are, they raise new challenges when engineers attempt to support all of them in one personal portable device. The packaging problems are exacerbated by the trend toward smaller and thinner devices.
Power use is another challenge. It takes a significant amount of electrical power to simultaneously support a number of display screens, especially if one of the screens is a large display area outside the device. Designers of battery-based personal portable devices are already concerned about their power budgets and look askance at any new feature that threatens to reduce the utility of the device by reducing how long the device can operate between charges.
The above considerations, and others, are addressed by the present invention, which can be understood by referring to the specification, drawings, and claims. According to aspects of the present invention, a personal portable device includes a microprojector that creates an image for display. The image is sent to a “beam-switching element” that shunts the image toward a selected display screen (e.g., a display screen on the device or an off-device projection surface). The image is then displayed on the selected screen. By commanding the beam-switching element to change its configuration, different screens can be driven by the same microprojector.
The combination of a single microprojector driving multiple display screens gives the personal portable device the flexibility of multiple displays while preserving space within the device and, in some embodiments, lowering power consumption. For example, a device can be designed that is very thin but still incorporates multiple display screens.
In some embodiments, the microprojector simultaneously drives more than one display screen. The driven display screens may display the same or different images, and the images displayed may be of the same or of different resolutions.
Power consumption is lowered in some embodiments by varying the amount of power consumed by the microprojector based on the display screen (or screens) in use at any one time. For example, less power could be consumed when off-device projection is not in use.
To enhance packaging flexibility, in some embodiments one or more light guides carry images from the beam-switching element to one or more display screens.
While the appended claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which:
a,
1
b, and 1c are block diagrams of a personal portable device with three display screens;
a is a simplified schematic view of a device directing an image to a display screen on the device, according to one aspect of the present invention;
b is a simplified schematic of the device of
c is a simplified schematic of the device of
Turning to the drawings, wherein like reference numerals refer to like elements, the invention is illustrated as being implemented in a suitable environment. The following description is based on embodiments of the invention and should not be taken as limiting the invention with regard to alternative embodiments that are not explicitly described herein.
a,
1
b, and 1c show a personal portable device 100 (e.g., a cellphone, personal digital assistant, or personal computer) that incorporates an embodiment of the present invention in order to support multiple display screens. This particular device 100 has three display screens. First,
When the device 100 is closed, as in
c illustrates a third display screen. In the figure, a user 106 is projecting an image 108 from her personal portable device 100. The image 108 could be, for example, a photograph, a video, or a computerized display from a word processor or an Internet browser. The image 108 may be projected onto a screen or even onto a wall or ceiling. By projecting the large, high resolution image 108 rather than presenting it on a (necessarily small) display screen 102 or 104 of her personal portable device 100, the user 106 can invite others to share the image 108 with her.
Prior to the present invention, the personal portable device 100 would have to incorporate within it three sets of display electronics, one set for each of the three display screens 102, 104, and 108. These three sets of display electronics increase the cost of the device 100 and consume significant amounts of its limited volume.
According to aspects of the present invention,
The projected light beam, modulated to incorporate the image information, is directed to a “beam-switching element” 204 (step 302 of
b shows the same personal portable device 100 of
Several technologies can be used for the microprojector 202. Depending upon economic and engineering factors, the microprojector 202 can incorporate an imager (either reflective or transmissive) or a laser or can be a hybrid.
There are also a number of ways of building the beam-switching element 204. A physically movable mirror can be used where the mirror moves between a first position when the display screen 206 is in use to a second position when the projection display is used. Semi-transparent and electrically configurable mirrors are also usable.
c shows an embodiment of the personal portable device 100 where the beam-switching element 204 is able to simultaneously send images to two different display screens 206 and 208. In one case, the beam-switching element 204 is electrically configurable, and in the scenario of
In another case, the beam-switching element 204 and the microprojector 202 are configured to simultaneously display a first image on the display screen 206 and a different image on the display 208. The microprojector 202 creates both images, possibly on different portions of its display area, and the beam-switching element 204 is directed to separate the images and to send them to the appropriate displays screens 206 and 208.
When different images are displayed simultaneously, they may be of the same or of different resolutions. For example, the image on the projection display 208 may be of high resolution, while a low-resolution status message is shown on the local display screen 206. The images, different or the same, and their resolutions, different or the same, are under the control of the control logic 200. The control logic 200 can direct the microprojector 202 so that some of its pixels are allocated to the projection display 208, while others are allocated to the local display screen 206. In some embodiments, the microprojector 202 has VGA resolution, that is, 640×480 pixels. Embodiments of the present invention are compatible with other image resolutions.
In some embodiments, the control logic 200 also varies the amount of power used by the microprojector 202 depending upon which, and how many, displays are in use at any one time. Because a projected image 108 is usually rather large and is often shown on a less-than-ideal surface, it often requires more light than is necessary to show an image on a local display screen 206. Thus, the control logic 200 may decrease the power used by the microprojector 202 whenever the projection display 208 is not in use. This feature gives the personal portable device 100 the ability to project images without incurring the cost of always driving the microprojector 202 at full power.
The embodiment in
Light guides can be used in conjunction with other embodiments (such as those of
In view of the many possible embodiments to which the principles of the present invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the invention. For example, the light paths in the figures are only meant to illustrate the functions of the various components and are not meant to be definitive. Other arrangements of the optical components shown in the figures and the addition of other known optical components are possible and may be called for in various environments. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof.
