Patent Publication Number: US-2011075056-A1

Title: Projection Display Apparatus

Description:
This application claims priority under 35 U.S.C. Section 119 of Japanese Patent Application No. 2009-225597 filed Sep. 29, 2009, entitled “PROJECTION DISPLAY DEVICE”. The disclosure of the above applications is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to projection display devices that modulate light from alight source and project the same onto a projection plane. 
     2. Disclosure of Related Art 
     Conventionally, projection display devices connectable to networks (hereinafter, referred to as “projectors”) have been developed. For example, the projectors can be configured to receive image signals from external devices (such as personal computers and the like) via networks and project images in accordance with the image signals. In this case, the projectors need to include a circuit section for extracting digital data corresponding to image signals from received communication signals and processing the same. Such a circuit section is comparatively expensive and therefore may lead to cost increase of the entire projector. 
     In another possible configuration of projectors, the projectors are connected to networks for the purpose of remote control of the projectors. In this case, the projectors only need to be capable of receiving control signals from the networks and transmitting signals indicative of projector status and the like to the network. This configuration does not require a circuit section for extracting digital data corresponding to image signals from communication signals and processing the same, whereby it is possible to suppress cost increase of the entire projector as compared to the foregoing mode. 
     Which of the foregoing two configurations is desired depends on a user. Accordingly, it is desired that projectors are adaptively configured to respond smoothly to the user&#39;s needs while suppressing cost increase as much as possible. 
     SUMMARY OF THE INVENTION 
     A principal aspect of the present invention relates to a projection display device that modulates light from a light source and projects the same onto a projection plane. A projection display device in this aspect includes a first communication processing section for performing communications over a network; an interface that is connected to a communication device having a second communication processing section with more advanced processing capability than that of the first communication processing section; and a selecting section that selects the first communication processing section or the second communication processing section disposed in the communication device, for use in communications with the network. 
     According to the projection display device in the principal aspect of the present invention, a user can select as appropriate between a communication mode with the first communication processing section and a communication mode with the second communication processing section. In addition, the second communication processing section is disposed in the communication device which is an external communication device, not in the projection display device, thereby allowing the projection display device to circumvent cost increase due to the second communication processing section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects and novel features of the present invention will be more fully understood from the following description of the preferred embodiments when reference is made to the accompanying drawings. 
         FIG. 1  is a diagram showing a configuration of a projector in an embodiment of the present invention; 
         FIG. 2  is a diagram showing a configuration of an optical engine in the embodiment; 
         FIG. 3  is a circuit block diagram showing a configuration of main components of the projector in the embodiment which relate to communications with an external device over a LAN; 
         FIG. 4  is a circuit block diagram showing a configuration of a functionality expansion unit in the embodiment; 
         FIG. 5  is a flowchart of a power supply controlling process on a LAN signal processing circuit section and the functionality expansion unit in the embodiment; 
         FIGS. 6A and 6B  are diagrams for describing a communication function setting process in modification example 1; 
         FIGS. 7A and 7B  are diagrams showing examples of a communication function setting window in modification example 1; 
         FIG. 8  is a flowchart of a power supply control process on the LAN signal processing circuit section and the functionality expansion unit in modification example 1; 
         FIG. 9  is a flowchart of a communication function setting process in modification example 2; 
         FIG. 10  is a flowchart of a power supply control process on the LAN signal processing circuit section and the functionality expansion unit in modification example 2; 
         FIG. 11  is a flowchart of a communication function setting process in modification example 3; and 
         FIG. 12  is a flowchart of a power supply control process on the LAN signal processing circuit section and the functionality expansion unit in modification example 4. 
     
    
    
     However, the drawings are only for purpose of description, and do not limit the scope of the present invention. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described below with reference to the drawings. 
     In this embodiment, a functionality expansion unit  50  is equivalent to a “communication device” recited in the claims; a LAN connector  401  is equivalent to a “first communication processing section” recited in the claims; a LAN signal processing circuit section  402  is equivalent to the “first communication processing section” recited in the claims; a linkage connector  403  is equivalent to an “interface” recited in the claims; a control section  407  is equivalent to a “selecting section”, a “setting section” and an “accepting section” recited in the claims; a power source section  408  is equivalent to a “power supply section” recited in the claims; an input section  409  is equivalent to the “accepting section” and the “setting section” recited in the claims; a LAN connector  501  is equivalent to a “second communication processing section” recited in the claims; a LAN signal processing circuit  502  is equivalent to the “second communication processing section” recited in the claims; and a digital communication signal processing circuit section  503  is equivalent to the “second communication processing section” recited in the claims. However, the foregoing correspondences between the claims and this embodiment are listed merely as examples, and the claims are not limited by this embodiment. 
       FIG. 1  is a perspective external view of a configuration of a projector. Referring to  FIG. 1 , the projector includes a cabinet  10  in the shape of a horizontally long, approximate rectangular parallelepiped. The cabinet  10  has a projection window  101  on a left side of a front surface thereof, and exhaust openings  102  and  103  for discharging air from an interior of the cabinet  10  on a right side of the front surface and a right surface thereof. In addition, the cabinet  10  has on a top surface thereof an operating section  104  with a plurality of operation buttons. 
     The cabinet  10  has therewithin an optical engine  20  and a projection lens  30 . The optical engine  20  generates image light modulated by an image signal. The projection lens  30  is attached to the optical engine  20 , and a front end of the projection lens  30  is exposed forward at the projection window  101 . The projection lens  30  enlarges and projects the image light generated by the optical engine  20  onto a screen plane arranged in front of the projector. 
       FIG. 2  is a diagram showing a configuration of the optical engine  20 . 
     As shown in  FIG. 2 , the optical engine  20  includes a light source  201 , a light-guiding optical system  202 , three transmissive liquid crystal panels  203 ,  204 , and  205 , and a dichroic prism  206 . In addition, polarizers (not shown) are disposed at incident sides and output sides of the liquid crystal panels  203 ,  204 , and  205 . 
     The light-guiding optical system  202  separates white light emitted from the light source  201  into a red-waveband light (hereinafter, referred to as “R light”), a green-waveband light (hereinafter, referred to as “G light”), and a blue-waveband light (hereinafter, referred to as “B light”), and then radiates the separated lights to the liquid crystal panels  203 ,  204 , and  205 . The liquid crystal panels  203 ,  204 , and  205  modulate the R, G, and B lights, and then the dichroic prism  206  combines the modulated lights and emits the same as image light. 
     As imagers constituting the optical engine  20 , there may be used reflective liquid crystal panels or MEMS devices, instead of the transmissive liquid crystal panels  203 ,  204 , and  205 . In addition, the optical engine  20  may be not a three-plate optical system with three imagers as described above but a single-plate optical system using one imager and a color wheel, for example. 
     The projector of this embodiment is capable of communication with an external device such as a personal computer or the like over a local area network (LAN), and is equipped with arrangements for that purpose. 
       FIG. 3  is a circuit block diagram showing a configuration of main components of the projector which relate to communications with an external device over the LAN. 
     The projector includes a LAN connector  401 , a LAN signal processing circuit section  402 , a linkage connector  403 , a digital communication signal processing circuit section  404 , an image signal processing section  405 , a panel driving control section  406 , a control section  407 , a power source section  408 , an input section  409 , and a memory  410 . 
     If the LAN signal processing circuit section  402  is to be used, the LAN connector  401  is connected with a LAN cable for LAN communications. 
     A communication signal from the LAN is input into the LAN signal processing circuit section  402  via the LAN connector  401 . This communication signal from the LAN contains a control signal from the external device for remote control of the projector. The LAN signal processing circuit section  402  subjects the communication signal from the LAN to a decoding process and the like for conversion into a digital communication signal capable of being processed by the projector. The LAN signal processing circuit section  402  then outputs the converted signal to the control section  407 . 
     The linkage connector  403  is connected to a functionality expansion unit  50 . The functionality expansion unit  50  is configured as a device separated from the projector. 
       FIG. 4  is a circuit block diagram showing a configuration of the functionality expansion unit  50 . 
     The functionality expansion unit  50  includes a LAN connector  501 , a LAN signal processing circuit section  502 , a digital communication signal processing circuit section  503 , a control section  504 , and a linkage connector  505 . 
     If the functionality expansion unit  50  is to be used, the LAN connector  501  is connected with a LAN cable for LAN communications. 
     A communication signal from the LAN is input into the LAN signal processing circuit section  502  via the LAN connector  501 . This communication signal from the LAN contains a control signal from the external device for remote control of the projector. Further, the communication signal also contains an image signal from the external device and a control signal from the external device used for image display. The LAN signal processing circuit section  502  subjects the communication signal from the LAN to a decoding process and the like for conversion into a digital communication signal capable of being processed by the digital communication signal processing circuit section  503 . The LAN signal processing circuit section  502  then outputs the converted signal to the digital communication signal processing circuit section  503 . 
     The digital communication signal processing circuit section  503  extracts an image signal from the input digital communication signal. The digital communication signal processing circuit section  503  then converts the extracted image signal into an image signal in a transmission mode suitable for communications with the digital communication signal processing circuit section  404  on the projector side, for example, in a low voltage differential signaling (LVDS) mode, and outputs the same to the linkage connector  505 . 
     In addition, the digital communication signal processing circuit section  503  also extracts a control signal from the input digital communication signal, and outputs the same to the control section  504 . 
     The control section  504  controls the LAN signal processing circuit section  502  and the digital communication signal processing circuit section  503  for proper execution of signal processing. The control section  504  also outputs the control signal from the digital communication signal processing circuit  503  to the linkage connector  505 . 
     The linkage connector  505  is connected to the linkage connector  403  on the projector side via a dedicated cable or the like, and transmits the input image signal and control signal to the linkage connector  403 . 
     Returning to  FIG. 3 , the image signal from the functionality expansion unit  50  is input into the digital communication signal processing circuit section  404  via the linkage connector  403 . The digital communication signal processing circuit section  404  converts the input image signal into digital image signals corresponding to RGB lights, and outputs the same to the image signal processing section  405 . 
     The image signal processing section  405  generates drive signals from the input image signals to drive the liquid crystal panels  203 ,  204 , and  205  for RGB lights, and outputs the same to the panel driving control section  406 . The panel driving control section  406  drives the liquid crystal panels  203 ,  204 , and  205 , in accordance with the respective drive signals. 
     A control signal from the functionality expansion unit  50  is input into the control section  407  via the linkage connector  403 . 
     When a control signal for remote control is input from the LAN signal processing circuit section  402  or the functionality expansion unit  50 , the control section  407  executes various kinds of control in accordance with the control signal. For example, if the control signal is a signal for an instruction to start operation, the control section  407  starts operation of the projector in a standby status, and if the control signal is a signal for an instruction to stop operation, the control section  407  stops the projector in an operational status. 
     In addition, when a control signal for use in image display is input from the functionality expansion unit  50 , the control section  407  executes a process for synchronizing the digital communication signal processing circuit section  404 , the image signal processing section  405 , and the panel driving control section  406  or the like, in accordance with the control signal. 
     Further, when a control signal for an instruction to acquire information on projector status, for example, an operational status of the projector (whether in operation or on standby), information on light source output (whether the light source turns on in a normal mode or a power-saving mode), and information on light source temperature or the like is input, the control section  407  acquires these kinds of information. 
     If the LAN signal processing circuit section  402  is in operation, the control section  407  outputs an information signal indicating the acquired projector status to the LAN signal processing circuit section  402 . The LAN signal processing circuit section  402  subjects the input information signal to a coding process and the like for conversion into a communication signal capable of being transmitted over the LAN, and outputs the same to the LAN via the LAN connector  401 . 
     Meanwhile, if the functionality expansion unit  50  is in operation, the control section  407  outputs the foregoing information signal to the digital communication signal processing circuit section  404 . 
     The digital communication signal processing circuit section  404  converts the input information signal into an information signal in a transmission mode suitable for communications with the digital communication signal processing circuit section  503  on the functionality expansion unit  50  side, for example, an information signal in a serial mode, and sends the same to the digital communication signal processing circuit section  503  via the two linkage connectors  403  and  505 . 
     The digital communication signal processing circuit section  503  converts the input information signal into an information signal capable of being processed by the LAN signal processing circuit section  502 , and sends the same to the LAN signal processing circuit section  502  via the control section  504 . The LAN signal processing circuit section  502  subjects the input information signal to a coding process and the like for conversion into a communication signal capable of being transmitted over the LAN, and outputs the same to the LAN via the LAN connector  501 . 
     Accordingly, the information signal indicating a projector status is transmitted to the external device over the LAN. 
     The power source section  408  supplies power to the LAN signal processing circuit section  402 . The power source section  408  also supplies power to the functionality expansion unit  50  via the linkage connector  403 . Further, the power source section  408  supplies power to each components such as the control section  407  and the light source  201 . For convenience&#39; sake,  FIG. 3  shows only a power line to the LAN signal processing circuit section  402  and the functionality expansion unit  50  by arrows. 
     When the functionality expansion unit  50  is connected to the linkage connector  403 , the functionality expansion unit  50  outputs a connection signal indicating this connection state to the control section  407  via the linkage connector  403 . Depending on the presence or absence of a connection signal, the control section  407  determines whether the functionality expansion unit  50  is connected. 
     The input section  409  outputs a control signal in accordance with a key operation on the operation section  104  or a control signal in accordance with a key operation on a remote control (not shown) to the control section  407 . A user can perform a key operation with the operation section  104  or the remote control to select whether to provide the projector with a communication function (hereinafter, referred to as “presence or absence of a communication function”). When any setting is made on the presence or absence of a communication function, the control section  407  stores the setting in the memory  410 . 
     The control section  407  controls the power source section  408 , depending on the setting of presence or absence of a communication function and the presence or absence of connection of the functionality expansion unit  50 . The control of the power source section  408  will be described later with reference to  FIG. 5 . 
     The control section  407  is connected to the memory  410 . The memory  410  stores a control program for providing the control section  407  with a control function. The control section  407  has a CPU to control components in accordance with the control program. In addition, the memory  410  stores various kinds of information on setting made by the user through the input section  409 . 
       FIG. 5  is a flowchart of a power supply control process on the LAN signal processing circuit section  402  and the functionality expansion unit  50 . 
     The control section  407  first makes a determination on the presence or absence of a communication function (S 101 ). When communication is performed with an external device over the LAN, a user makes a setting of “With a communication function” through a key operation. Meanwhile, if not performing communications with an external device, the user makes a setting of “Without a communication function” through a key operation. 
     If the setting is “Without a communication function” (S 101 : NO), the control section  407  controls the power source section  408  so as not to supply power to both the LAN signal processing circuit section  402  and the functionality expansion unit  50  (S 102 ). 
     Meanwhile, if the setting is “With a communication function” (S 101 : YES), the control section  407  then determines whether the functionality expansion unit  50  is connected (S 103 ). 
     If the projector is connected to the external device over the LAN only for the purpose of remote control or status monitoring of the projector, the functionality expansion unit  50  is generally not connected because communications can be performed only with the LAN signal processing circuit section  402  built into the projector. 
     If determining at step S 103  that the functionality expansion unit  50  is not connected (S 103 : NO), the control section  407  controls the power source section  408  so as to supply power to the LAN signal processing circuit section  402 . At the same time, the control section  407  controls the power source section  408  so as not to supply power to the functionality expansion unit  50  via the linkage connector  403  (S 104 ). 
     Accordingly, the LAN signal processing circuit section  402  is activated so that a control signal for remote control and an information signal indicating a projector status are transmitted and received through the LAN signal processing circuit section  402 , as described above. 
     Meanwhile, if the projector is connected to the external device over the LAN for the purpose of allowing the projector to project an image from the external device, in addition to remote control or status monitoring of the projector, the user connects the functionality expansion unit  50 , because an image signal cannot be communicated only with the LAN signal processing circuit section  402  built into the projector. 
     If determining at step S 103  that the functionality expansion unit  50  is connected (S 103 : YES), the control section  407  controls the power source section  408  so as to supply power to the functionality expansion unit  50  via the linkage connector  403  and so as not to supply power to the LAN signal processing circuit section  402  (S 105 ). 
     Accordingly, the functionality expansion unit  50  is activated so that an image signal, a control signal for remote control, and an information signal indicating a projector status are transmitted and received through the functionality expansion unit  50 , as described above. 
     These steps S 101  to S 105  are repeatedly carried out while the projector is powered and the control section  407  is in operation. 
     In this embodiment, as described above, the user can make a selection on whether to use the LAN signal processing circuit section  402  built into the projector or use the functionality expansion unit  50 , depending on the kind of a signal received over the LAN. 
     Therefore, if communications can be performed only with the LAN signal processing circuit section  402 , there is no need to use the functionality expansion unit  50 . This saves the user from having to connect the functionality expansion unit  50  or purchase the functionality expansion unit  50  at a store or the like. In addition, the LAN signal processing circuit section  402  requires a smaller amount of power consumption than that required for the functionality expansion unit  50 , thereby reducing power consumption of the projector. 
     Further, the projector mainly includes the LAN signal processing circuit section  402 , which achieves reduction in cost for the projector as compared to the case where the function of the functionality expansion unit  50  is implemented within the projector. 
     According to this embodiment, as described above, it is possible to provide a projector that allows adaptive selection of a network communication mode while suppressing cost increase. 
     Modification Example 1 
     In the foregoing embodiment, whether to use the LAN signal processing circuit section  402  or the functionality expansion unit  50  is selected depending on the presence or absence of connection of the functionality expansion unit  50  to the projector. In this modification example, alternatively, the user selects whether to use the LAN signal processing circuit section  402  or the functionality expansion unit  50 , through an input operation with the operation section  104  or the remote control. 
       FIG. 6A  is a flowchart of a communication function setting process in modification example 1.  FIG. 6B  is a diagram showing setting data corresponding to setting options in modification example 1.  FIGS. 7A and 7B  show display examples of a communication function setting window in modification example 1. 
     When the user performs a key operation for displaying a communication function setting window, the control section  407  displays the communication function setting window on a screen (S 211 ). At that time, if the functionality expansion unit  50  is not connected, the window offers two options “Without communication function” and “LAN signal processing circuit section” as shown in  FIG. 7A . Meanwhile, if the functionality expansion unit  50  is connected, the window offers three options “Without communication function”, “LAN signal processing circuit section”, and “Function expansion unit”, as shown in  FIG. 7B . The user selects a desired one of the options in the communication function setting window. For example, the user highlights a desired option and confirms the selection, as shown in the screens of  FIGS. 7A and 7B . 
     If the option “Without a communication function” is selected (S 212 : YES), the control section  407  makes a setting of not using a communication function (S 214 ). In this case, setting data “0” is stored in a predetermined storage area of the memory  410 , as shown in  FIG. 6B . If the option “LAN signal processing circuit section” is selected (S 213 : NO), the control section  407  makes a setting of using the LAN signal processing circuit section  402  (S 215 ). In this case, setting data “1” is stored in the predetermined storage area of the memory  410 , as shown in  FIG. 6B . If the option “Functional expansion unit” is selected (S 213 : YES), the control section  407  makes a setting of using the functionality expansion unit  50  (S 216 ). In this case, setting data “2” is stored in the predetermined storage area of the memory  410 , as shown in  FIG. 6B . 
       FIG. 8  is a flowchart of a power supply control process on the LAN signal processing circuit section  402  and the functionality expansion unit  50  in modification example 1. 
     The control section  407  first checks the setting data stored in the memory  410  (S 111 ). Then, the control section  407  determines which of the setting data is stored (S 112 ). In the case of the setting data “0”, that is, the setting of not using a communication function, the control section  407  controls the power source section  408  so as not to supply power to both the LAN signal processing circuit  402  and the functionality expansion unit  50  (S 113 ). In the case of the setting data “1”, that is, the setting of using the LAN signal processing circuit section  402 , the control section  407  controls the power source section  408  so as to supply power to the LAN signal processing section  402  and so as not to supply power to the functionality expansion unit  50  (S 114 ). In the case of the setting data “2”, that is, the setting of using the functionality expansion unit  50 , the control section  407  controls the power source section  408  so as to supply power to the functionality expansion unit  50  and so as not to supply power to the LAN signal processing circuit  402  (S 115 ). 
     While the control section  407  is in operation, the foregoing steps S 111  to S 115  are repeated. 
     In this manner, the configuration of modification example 1 can produce the same advantage as that of the foregoing embodiment. In addition, modification example 1 allows a user to select arbitrarily the communication processing section to be used, which results in increased convenience of a user. 
     Modification Example 2 
     When the projector is powered, the control section  407  and other necessary circuit sections are activated to bring the projector into a standby status. After that, when the user presses a power switch on the operation section  104  or the remote control to start operation, the lamp and the liquid crystal panels are driven to start projection of an image. 
     In modification example 1 described above, it is not possible to set a communication function separately for a standby status and an operational status. 
     In some cases, however, different kinds of signals may be communicated between when the projector is on standby and when the projector is in operation. For example, in the configuration where an image signal is to be transmitted to the projector over the LAN, the image signal, a control signal for remote control, and an information signal indicating a projector status may be communicated while the projector is in operation, whereas no image signal is communicated while the projector is on standby. 
     Accordingly, modification example 2 is configured to allow separate settings of a communication function for a standby status and an operational status of the projector. 
       FIG. 9  is a flowchart of a communication function setting process in modification example 2. 
     When the user performs a key operation for displaying a communication function setting window, the control section  407  determines whether a setting for a standby status is made (S 221 ). If the setting for a standby status is not made (S 221 : NO), the control section  407  first displays a communication function setting window for making a setting for a standby state on the screen (S 222 ). At that time, the communication function setting window is the same as that shown in  FIGS. 7A and 7B , and may include an additional indication of the setting for a standby status as appropriate. The user selects a desired option for the setting for a standby status. 
     If the option “Without a communication function” is selected in this window (S 223 : YES), the control section  407  makes a setting of not using a communication function (S 225 ). If the option “LAN signal processing circuit section” is selected (S 224 : NO), the control section  407  makes a setting of using the LAN signal processing circuit section  402  (S 226 ). If the option “Functionality expansion unit” is selected (S 224 : YES), the control section  407  makes a setting of using the functionality expansion unit  50  (S 227 ). 
     The setting data corresponding to the setting options are the same as those in modification example 1, as shown in  FIG. 6B . If the user selects any option, the setting data corresponding to the option (“0”, “1”, or “2”) is stored in a storage area for a standby status of the memory  410 . 
     Accordingly, upon completion of the setting for a standby status (S 228 : NO→S 221 : YES), the control section  407  then displays a communication function setting window for making a setting for an operational status (S 229 ). This communication function setting window is also the same as those shown in  FIGS. 7A and 7B , and may include an additional indication of the setting for an operational status as appropriate. 
     When the setting is made in the same manner as that for a standby status (S 223  to S 227 ), the setting data corresponding to the selected option (“0”, “1”, or “2”) is stored in a storage area for an operational status of the memory  410 . Accordingly, the settings of the communication processing sections for a standby status and an operational status are completed. 
       FIG. 10  is a flowchart of a power supply control processing on the LAN signal processing circuit section  402  and the functionality expansion unit  50  in modification example 2. 
     The control section  407  first determines whether the projector is in a standby status or in an operational status (S 121 ). Then, if the projector is in a standby status (S 121 : standby status), the control section  407  checks the setting data for a standby status (S 122 ), and controls the power source section  408  based on the setting data in the same manner as the case of modification example 1 (S 124  to S 127 ). 
     Meanwhile, if the projector is in an operational status (S 121 : Operational status), the control section  407  checks the setting data for an operational status (S 123 ), and controls the power source section  408  based on the setting data (S 124  to S 127 ). 
     In this manner, the configuration of modification example 2 allows the user to make a more detailed selection on whether to use the LAN signal processing circuit section  402  built into the projector or use the functionality expansion unit  50 , depending on the kind of a signal received over the LAN. 
     For example, even if the functionality expansion unit  50  is connected to support reception of an image signal as described above, there is a low possibility that the projector receives an image signal while the projector is on standby. In addition, the LAN signal processing circuit section  402  requires a smaller amount of power consumption than that required by the functionality expansion unit  50 . 
     Therefore, in this case, the user can make a setting such that the LAN signal processing circuit section  402  is used while the projector is on standby, and the functionality expansion unit  50  is used while the projector is in operation. If such a setting is made, the LAN signal processing circuit section  402  is powered and activated while the projector is on standby. In contrast, the functionality expansion unit  50  is powered and activated while the projector is in operation. 
     In this manner, it is possible to reduce power consumption of the projector as compared to the case where the functionality expansion unit  50  is constantly powered. 
     Modification Example 3 
       FIG. 11  is a flowchart of a communication function setting process in modification example 3. 
     In modification examples 1 and 2 described above, the setting of a communication function is made only through an input operation. In this modification example, firstly, a setting is made depending on the presence or absence of connection of the functionality expansion unit  50 . After that, the setting can be changed through an input operation. 
     Specifically, the control section  407  first determines whether the functionality expansion unit  50  is connected (S 231 ). If the functionality expansion unit  50  is not connected (S 231 : NO), the control section  407  makes a setting of using the LAN signal processing circuit section  402 (S 232 ). In contrast, if the functionality expansion unit  50  is connected (S 231 : YES), the control section  407  makes a setting of using the functionality expansion unit  50 (S 233 ). 
     If wishing to make a change to the previous setting, a user performs a key operation for displaying a communication function setting window (S 234 : YES). 
     Accordingly, if determining that the foregoing key operation is performed, the control section  407  executes a communication function setting process (S 211  to S 216 ) through an input operation, as shown in  FIGS. 6A and 6B  (S 235 ). 
     In this manner, in the configuration of modification 3, an automatic setting is first made on the basis of the presence or absence of connection of the functionality expansion unit  50 , and therefore the user only needs to perform an input operation in the case of making a change to the setting. This allows the user to make a setting by easy operation. 
     At step S 235 , the setting process shown in  FIG. 9  may be performed in place of the setting process shown in  FIGS. 6A and 6B . In this case, the control section  407  makes a setting of using the LAN signal processing circuit section  402  (“1”) in both of a standby status and an operational status at step S 232 , and the control section  407  makes a setting of using the functionality expansion unit  50  (“2”) in both of a standby status and an operational status at step S 233 . 
     Modification Example 4 
       FIG. 12  is a flowchart of a power supply control process on the LAN signal processing circuit section  402  and the functionality expansion unit  50  in modification example 4. 
     In this modification example, the user can select which of modes to be enabled, that is, a mode in which the LAN signal processing circuit section  402  or the functionality expansion unit  50  is automatically selected depending on the presence or absence of connection of the functionality expansion unit  50 , as in the foregoing embodiment, and a mode in which the LAN signal processing circuit section  402  or the functionality expansion unit  50  is selected according to the setting made by a user&#39;s an input operation, as in modification examples 1 and 2. 
     In the configuration of modification example 4, a user selects in advance whether an automatic setting of a communication function is to be on or off. 
     If the automatic setting is on (S 301 : YES), the control section  407  executes the power supply control shown in  FIG. 5  as in the foregoing embodiment (S 302 ). Meanwhile, if the automatic setting is off (S 301 : NO), the control section  407  executes the power supply control shown in  FIG. 8  as in modification example 1 (S 303 ). Otherwise, if the automatic setting is off (S 301 : NO), the control section  407  executes the power supply control shown in  FIG. 11  as in modification example (S 303 ). 
     In this manner, the configuration of modification 4 allows the user to be select one of the two modes described above for selecting the LAN signal processing circuit section  402  or the functionality expansion unit  50 . 
     Others 
     The embodiment of the present invention can further be modified in various manners besides the foregoing ones. 
     For example, in the foregoing embodiment, the external device and the projector are connected over a wired LAN. However, the present invention is not limited by this configuration, and the external device and the projector may be connected over a wireless LAN or any other network. 
     In addition, a combination of the first communication processing section and the second communication processing section in the present invention is not limited by the example of the foregoing embodiment. For example, any signal processing circuit section supporting wired LANs may be disposed as first communication processing section in the projector, and any signal processing circuit section supporting wireless LANs may be disposed as second communication processing section in the functionality expansion unit  50 . Since wireless LANs require the function of transmitting signals in a wireless manner, the signal processing circuit section supporting wireless LANs has more advanced capability than that of the LAN signal processing circuit section. 
     Alternatively, as second communication processing section, any signal processing circuit section supporting optical communications may be disposed in the functionality expansion unit  50 . Since optical communications require the function of converting an electrical signal into an optical signal, the signal processing circuit section supporting optical communications has more advanced capability than that of the LAN signal processing circuit section. 
     Besides, the embodiment of the present invention can be appropriately modified in various manners, within the scope of technical ideas recited in the claims.