Abstract:
A system includes a shutter which selectively allows access to an infrared detector, when accessed directly by a processor-based system, such as a set-top computer system. In this way, infrared commands may be blasted from a set-top computer system to an appliance, e.g., a television receiver, without interference from other remote control units. When the controlling device is not sending signals to the television receiver, the shutter may allow other remote control units to control the appliance. The shutter may be a voltage controlled liquid crystal shutter, whose transmissivity is a function of the applied voltage.

Description:
BACKGROUND 
     This invention relates generally to devices which may be controlled by infrared signals. 
     A variety of electronic devices are controlled by infrared signals. For example, television receivers may be controlled by a remote control which generates unidirectional infrared signals to control the settings of the television receiver. In addition, a number of processor-based systems, such as set-top computer systems, may be controlled using infrared remote control units. For example, a television receiver may be controlled by infrared transmissions, which may be communicated from a remote control unit or a set-top computer system situated on the television receiver. 
     The set-top personal computer system may be used to access Internet information that is viewed on a television receiver. In one embodiment, the set-top computer system may access an Internet site containing information about currently available television programs. The set-top computer may then convey-control signals via an infrared transmitter and cable to an infrared detector on the television receiver to control the timing of the television receiver based on inputs received from the user. Thus, as the user inputs commands to select a particular program displayed on the television receiver by the set-top personal computer system, the television tuner may be operated to select the desired program. 
     In many cases, the set-top computer provides an electronic signal to the television receiver, which may be conveyed through a cable. On its end remote from the computer system, the cable may include a transducer which converts electrical signals into infrared signals. These infrared signals are then blasted into the infrared detector on the television receiver. Commonly, the transducer is secured to the infrared detector cover using adhesive attachment. Thus, the commands from the set-top computer can be blasted directly into the television&#39;s infrared detector. 
     While infrared signals are being blasted directly from the set-top computer into the infrared detector on the television, the user may also operate a remote control-unit which similarly sends infrared signals that are received by the same infrared detector. These signals from the remote control unit interfere with the commands being transmitted by the computer system. 
     To overcome this problem, it is known to cover the television&#39;s infrared detector and common infrared transmitter with tape so only those signals transmitted from the set-top computer over a cable are received by the detector. Although this solves the interference problem, it creates another problem. In many cases, when the set-top personal computer is not sending commands to the television receiver, it is desirable to control the television receiver using the television remote control unit. While many of the same operations may be done using a remote control unit provided with the set-top personal computer system, some users may prefer to directly control the television receiver, without using the computer system. When the detector is taped over, this is not possible. 
     Thus, there is a need for a way to allow remote control units to be utilized in conjunction with set-top personal computer systems to control television receivers and other consumer electronic devices. 
     SUMMARY 
     In accordance with one embodiment, a shutter for an infrared detector includes a cover arranged to be mounted over the detector. An infrared port is formed in the cover. The infrared transmissivity of the port is selectively, electrically alterable. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of one embodiment of the present invention; 
     FIG. 2 is an enlarged cross-sectional view taken generally along the line  2 — 2  in FIG. 1; 
     FIG. 3 is an enlarged cross-sectional view taken generally along the line  3 — 3  in FIG. 2; 
     FIG. 4 is a flow chart showing one embodiment of software which may be used to implement the embodiment shown in FIG. 1; and 
     FIG. 5 is a block diagram of one embodiment for implementing the system shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     A video receiver  12 , which may be a television receiver, is coupled to a processor-based system  14 , such as a set-top computer system as shown in FIG.  1 . The system  14  may be controlled by a remote control unit (RCU)  16 , which may provide infrared signals to control either the computer system via an infrared detector  24  or the receiver  12  itself, via an infrared detector  22 . 
     The receiver  12  may include a display  18  and a window  20 , which may include a channel display indicator and the infrared detector  22 . The infrared detector  22  communicates with the system  14  via a cable  26 . 
     Control signals generated by the system  14  may be, conveyed through the cable  26 . As indicated in FIG. 2, the cable  26 , which may be called an “IR blaster”, communicates with an infrared emitter  34 , which converts electrical signals transmitted over the cable into infrared signals. These infrared signals may be directly “blasted” into an infrared detector  22  mounted in the video receiver  12 . The detected infrared signals may be converted into electrical signals and conveyed over a cable  28  for control of the video receiver  12 . For example, in one embodiment of the present invention, the cable  28  may couple a television tuner (not shown). 
     Associated with the transducer  34  is a cover  30 , which may be secured over the infrared detector  22 . For example, in one embodiment of the present invention, adhesive tabs  33  may be used to secure the cover  30 , so as to completely occlude the infrared detector  22 . The cable  26  may penetrate through the cover  30  to provide a cable wire  36 , which communicates with the emitter  34 , and a cable  38  which provides control signals to the cover  30 . The cover  30  may include a shutter  39 , which is selectively, electrically alterable to change its transmissivity to infrared radiation. 
     In one embodiment of the present invention, the shutter  39  is a liquid crystal shutter. By applying a potential over the cable  38  to the shutter, the shutter&#39;s transmissivity of infrared radiation may be selectively altered. In one embodiment of the present invention, the shutter  39  may be selectively switched in one mode, to allow infrared radiation to freely pass, and in another mode, to completely block incident infrared radiation from reaching the infrared detector  22 . 
     The cable  26 , as shown in FIG. 3, may include a sheath  41  which covers a pair of ground wires  40  and the wires  36  and  38 , described previously. Thus, control signals to control the shutter may be transmitted in the same cable that also transmits signals which control the emitter  34 . 
     Turning now to FIG. 4, the software  42  for controlling the shutter  39  may be stored in the processor-based system  14 , as will be described hereinafter. Initially, a check at diamond  44  determines whether a blaster signal is being transmitted by the system  14  over the cable  36  to the video receiver  12 . If so, the signal is provided over the cable  26  through the transducer  34 , and fed into the infrared detector  22  (block  46 ). At the same time, a signal is provided over the cable  38  to change the transmissivity of the shutter  39 . Namely, the shutter  39  is made opaque to block infrared radiation, as indicated in block  48 , using well known liquid crystal shutters. If there is no ongoing transmission over the cable  26 , the shutter  39  can be caused to become transparent, as indicated in block  50 , and the flow ends. 
     Liquid crystal shutters are electrically controllable to control the transmissivity of a liquid crystal material. Namely, by applying an appropriate potential, the polarization of the liquid crystal element may be controlled. Conventionally, liquid crystal shutters may include a neutral linear polarizer. Neutral linear polarizers are commercially available from a variety of companies, including Polaroid Corporation of Cambridge, Mass. Behind the polarizer may be a liquid crystal. The liquid crystal may include a pair of glass substrates, which may, for example, be made of borosilicate glass. A liquid crystal material contained between the glass substrates may pass light in only one polarization. Thus, by controlling the polarization of the neutral linear polarizer, the ability of the device to pass light may be selectively, electrically controlled. 
     Referring now to FIG. 5, an example of a system for providing the capabilities described previously may involve either a computer, television receiver, set-top computer system, or another appliance. The illustrated system  14  includes a processor  100  coupled to an accelerated graphics port (AGP) chipset  102 . AGP is described in detailed in the  Accelerated Graphics Port Interface Specification , Revision 2.0, published in 1998 by Intel Corporation of Santa Clara, Calif. The AGP chipset  102  may, in turn, be coupled to system memory  104  and a graphics accelerator  106 . The graphics accelerator  106  may be coupled to a video receiver  12 . 
     The chipset  102  may also be coupled to a bus  108 , which may in turn be coupled to a television tuner/capture card  110 . The tuner/capture card  110  may be coupled to a television input signal  112 . The television input signal  112  may, for example, be a conventional television antenna, satellite antenna, cable connection, or other television input. The tuner/capture card  110  may receive television signals in one video format and convert them into a format used by the system  14 . 
     The bus  108  may also be coupled to another bridge  114 , which in turn, couples a hard-disk drive  116 . The hard-disk drive  116  may store the software  42 . 
     The bridge  114  may be coupled to a bus  115 , coupled to a serial input/output (SIO) device  122 , a network  120 , and a basic input/output system (BIOS)  124 . The SIO device  122  may interface to a keyboard  128 , an infrared emitter  34 , and a liquid crystal shutter  139 . In addition, the SIO device  122  may also be coupled to the RCU  16  through an IR receiver  24  to enable the system to receive inputs from a wireless remote control. The network  120  may, for example, be a connection to a telephone network, local area network or cable connection. 
     The infrared emitter  34  may, for example, be in accordance with the Infrared Data Association protocols, e.g., the Serial Infrared Visible Layer Link Specification, Version 1.2, dated Nov. 30, 1997. Alternatively, the infrared emitter  34  may be a legacy infrared device. The remote control unit  16  may be include a keypad  132 , coupled to an infrared transmitter  134 , which transmits the infrared signal received by the infrared emitter  34 . A controller  136  may control the transmitter  134  and receive information from the keypad  132 . The controller  136  may have associated with it memory  138 , which in one illustrated embodiment, may be nonvolatile random access memory (NVRAM). 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations, as fall within the true spirit and scope of the present invention.