Stereographic display device

[0002] This invention relates to stereographic display devices and more particularly to such devices as an integral part of an item of apparel such as a pair of glasses or a helmet.

[0003] In current technology for head mounted display (HMD) devices a single display device is used for each eye of the viewer. This is costly because it requires not only a second display device but also additional drive electonics. One solution is to use a single display device and liquid crystal optical shutters to route the images to the appropriate eye. This however is limited by the relatively slow shutter speeds of from about 10 msec to 50 msec which can be further slowed at low temperatures, causing flicker.

[0004] A stereographic display system comprises a signal processing unit receptive of stereo images originating from stereo image sources at a prescribed frame rate. The stereographic display system is operative to generate a multiplexed image stream and a series of synchronization pulses. An image display device is receptive of the multiplexed image stream and operative to display the multiplexed image stream as multiplexed stereo images. A phase-locked loop is receptive of the series of synchronization pulses from the signal processing unit. An optical signal filter system is coupled to the phase-locked loop and receptive of the multiplexed stereo images. The optical signal filter system includes rotating polarization filters that alternately pass or block the passage of a first and second image of the multiplexed stereo images.

[0005] The stereographic display system may be made, in whole or in part, an integral part of an item of apparel such as a pair of glasses or a helmet or headdress.

[0006] FIG. 1 is a schematic block diagram of a stereographic display system receptive of stereographic images.

[0007] FIG. 2 is a schematic block diagram of a phase locked loop in the stereographic display system of FIG. 1.

[0008] FIG. 3 is a first schematic diagram of the arrangement of polarizing filters in the stereographic display device of FIG. 1 passing a first beam of polarized light.

[0009] FIG. 4 is a second schematic diagram of the arrangement of polarizing filters in the stereographic device of FIG. 1 passing a second beam of polarized light.

[0010] FIG. 5 is a second schematic diagram of the stereographic display device of FIG. 2 passing the first beam of light.

[0011] FIG. 6 is a second schematic diagram of the stereographic display device of FIG. 3 passing the second beam of light.

[0012] FIG. 7 is a schematic diagram of the stereographic display system of FIG. 1 in communication with remote stereographic display devices via a communications or computer network.

[0013] FIG. 8 is a view of the stereographic display system of FIG. 1 integrally mounted on an article of apparel such as viewing glasses.

[0014] FIG. 9 is a view of the a segment of the stereographic display system of FIG. 1 integrally mounted in an article of apparel such as viewing glasses.

[0015] FIG. 10 is a view of the stereographic display system of FIG. 1 integrally mounted in an article of apparel such as a helmet or headdress.

[0016] FIG. 11 is a view of the a segment of the stereographic display system of FIG. 1 integrally mounted in an article of apparel such as viewing glasses.

[0017] FIG. 12 is a third schematic diagram of the arrangement of polarizing filters in the stereographic display device of FIG. 1 passing a first beam of polarized light.

[0018] FIG. 13 is a fourth schematic diagram of the arrangement of polarizing filters in the stereographic display device of FIG. 1 passing a first beam of polarized light.

[0019] In FIG. 1, a stereographic display system is shown generally at 100. The stereographic display system 100 is receptive of stereographic images or data 122 at a frame rate, f_roriginating from stereographic image or data sources 120 such as personal computers, video cameras, game consoles, video discs or other stereographic devices which can act as a source of stereographic images or data. A signal or data processing unit, such as a video processor 124, which includes a synchronization extractor or calculator, receives the stereographic images or data 122 and generates thereby a set of output signals 118R, 118L, 126. As best understood, the term stereographic is synonymous with the term stereoscopic. A first video processor output signal 118R, 118L comprises an electronic signal in the nature of a multiplexed image or data stream. The multiplexed image or data stream 118R, 118L may be for example left and right images which are directed to an image or data display device 102 such as a cathode ray tube display (CRT). The image or data display device 102 provides as output an optical signal 112R, 112L in the nature of a set of left and right stereographic images or data. The left and right stereographic images 112R, 112L are directed to a multiplexing optical filter system 150. The multiplexing optical filter system 150 comprises a set of rotatable filters 104, 106, 108 which, in combination, alternately pass and block the stereographic images or data 112R, 112L. A second video processor output signal 126 comprises a series of synchronization pulses for synchronizing the rotational velocities, ω_C, ω_R, ω_Lof the set of filters 104, 106, 108 rotated by a motor 136 (not shown in FIG. 1, but to be explained more fully below). The synchronization pulse rate, f_p, is an integer multiple of the frame rate, e.g., f_p=nf_r. A phase-locked loop (PLL) 146 is receptive of the second video processor output signal 126 and operative thereby to rotate 138 the set of filters 104, 106, 108 at the aforesaid rotational velocities ω_C, ω_R, ω_L. Since the filters 104, 106, 108 are coupled to the motor 136, the rotational velocities, ω_C, ω_R, ω_L, thereof are directly related to the motor rotational velocity, ω_M.

[0020] FIG. 2 shows a schematic block diagram of the phase-locked loop 146 of FIG. 1. The phase-locked loop 146 comprises a digital signal processing (DSP) unit or microprocessor 128 receptive of the synchronization pulses of the second video processor output signal 126 and calculates a desired motor rotational velocity, ω_M, and motor (or filter) phase, φ_M, for any given frame rate, f_r. The digital signal processing unit or microprocessor 128 provides as output a motor speed command signal 130. A controller 132 is receptive of the motor speed command signal 130 and provides as output a motor drive signal 134 which is directed to the motor 136. The motor 136 thereby rotates 138 the set of filters 104, 106, 108 which are receptive of stereographic images or data 112R, 112L from the image or data display device 102. The motor 136 includes a sensor 142 for sensing the motor rotational velocity, ω_M. The sensed motor rotational velocity, ω_S, is fed back to the controller 132 and to the digital signal processing unit or microprocessor 128 as a set of pulses 140 for synchronization with the synchronization pulses of the second video processor output signal 126.

[0021] Reference is now made to FIGS. 3, 4, 5, 6, 12 and 13 which should be viewed in conjunction with one another. In FIGS. 3 and 5 the image or data display device 102 and the filters 104, 106, 108 are shown positioned with respect to one another receiving the stereographic images or data 112R, 112L and also with respect to an axis 110. The filters 104, 106, 108 are polarization filters, each having a transmission axis 104a, 106a, 108asuch that light, polarized parallel to the transmission axis passes therethrough, and light polarized perpendicular to the transmission axis is blocked from passing therethrough. As such, in FIG. 5, the stereographic images or data 112R, 112L, polarized parallel to the transmission axis 104aof the first filter 104, pass through the first filter 104 and further pass through the second filter 106 when the transmission axis 106aof the second filter 106 is parallel to the transmission axis 104aof the first 104. However, the stereographic images or data 112R, 112L will not pass through the third filter 108 when the transmission axis 108aof the third filter 108 is perpendicular to the transmission axis 104aof the first filter 104. Thus, the viewer 152 perceives the stereographic images or data 112R in his/her right eye at 114 but does not perceive the stereographic images or data 112R in his/her left eye at 116.

[0022] Conversely, in FIGS. 4 and 6 the image or data display device 102 and the filters 104, 106, 108 are again shown positioned with respect to one another receiving the stereographic images or data 112R, 112L and also with respect to the axis 110. As such, in FIG. 6, the stereographic images or data 112R, 112L, polarized parallel to the transmission axis 104aof the first filter 104, pass through the first filter 104 and further pass through the third filter 108 when the transmission axis 108aof the third filter 108 is parallel to the transmission axis 104aof the first filter 104. However, the stereographic images or data 112R, 112L will not pass through the second filter 106 when the transmission axis 106aof the second filter 106 is perpendicular to the transmission axis 104aof the first filter 104. Thus, the viewer 152 perceives the stereographic images or data 112L in his/her left eye at 116 but does not perceive the stereographic images or data 112L in his/her right eye at 114.

[0023] In FIGS. 5 and 6 it is seen that the second filter 106 and third filter 108 rotate either in a clockwise or a counterclockwise direction at an angular velocity of ω_Rand ω_Lrespectively (e.g., approximately 120π radians per sec or greater.). It is also seen that the transmission axes 106a, 108aof the second and third filters 106, 108 are at right angles with respect to one another (i.e., 90 degrees out of phase). Thus, as the second and third filters 106, 108 rotate at ω_Rand ω_L, the viewer 152 alternately perceives aright stereographic image or data 112R and left stereographic image or data 112L version of the stereographic images or data stream 118R and 118L through the multiplexing filters 104, 106, 108 at 114 and 116 at the frame rate f_r; or at one half of the frame rate for each eye. The second and third filters 106, 108 may rotate in the same direction or in opposite directions and are synchronized to be rotated by the same motor 136. The first filter 104 may be stationary or alternatively may also rotate either clockwise or counterclockwise at ω_C. When the first filter 104 is rotated, the rotation rates of the second and third filters, ω_Rand ω_L, 106, 108 are adjusted so as to maintain the alternate perception of the stereographic images or data 112R, 112L by the viewer 152 at the aforesaid frame rates. Thus, when the first filter 104 is rotated, ω_C=2nω_Ror 2nω_L, where n is an integer. It will thus be understood that FIGS. 5 and 6 represent a “snapshot” of the stereographic display system 100 as the second and third filters 106, 108 rotate.

[0024] It will also be understood from FIGS. 3, 4, 5, 6, 12 and 13 that the order in which the filters 104, 106, 108 are positioned with respect to the reception of the stereographic images or data 112R, 112L is immaterial. In other words, filters 106, 108 can be positioned, either in combination or separately, so as to receive the stereographic images or data 112R, 112L prior to the reception thereof by filter 104 (FIGS. 12 and 13).

[0025] Referring to FIG. 7, the stereographic display system 100 is shown connected to a communications network 200, such as a local area network (LAN) or a wide area network (WAN) or the internet. The communications network 200 includes a plurality of stereographic images or data sources 120 such as personal computers, video cameras, game consoles video discs or other stereographic video devices connected thereto from remote geographical locations by wired or wireless connections, by radio based communications, by telephony based communications, or by other network-based communications. The stereographic display system 100 may also be connected directly to other like stereographic display systems 100 for displaying the image or data source 120. The communications network 200 may be similarly connected to other networks and includes network devices configured to execute program software, that allows them to send, receive, store, record and process images either separately or in combination, between and amongst themselves via the network 200. Such processing includes, for example, computer generated holography, image compression and decompression, filtering, contrast enhancement, image sharpening, noise removal and correlation for image classification.

[0026] Referring to FIGS. 8, 9, 10 and 11, it will be seen that the stereographic display system 100 of FIG. 1 may be made, in whole or in part, an integral part of an item of apparel such as a pair of glasses 300 or a helmet or headdress 400. In FIG. 8 the stereographic display system 100 is mounted on the pair of glasses 300, viewable therefrom and receptive of the stereographic images or data 122. In FIG. 9, the motor, sensor combination 136, 142, the image display device 102 and the multiplexing optical filter system 150 are made an integral part of the pair of glasses 300 and receive the multiplexed image or data stream 118R, 118L, the motor drive signal 134 and provide the set of feedback pulses 140. In FIG. 10 a helmet or headdress 400 contains the stereographic display system 100 and is worn by a viewer about the head and viewable therefrom. In FIG. 11, the motor, sensor combination 136, 142 and the multiplexing optical filter system 150 are made an integral part of the pair of glasses 300 and receive the stereographic images or data 112R, 112L, the motor drive signal 134 and provide the set of feedback pulses 140.