Patent Publication Number: US-2023156166-A1

Title: Projector controlling method and projection system

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-186237, filed Nov. 16, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a projector controlling method and a projection system. 
     2. Related Art 
     There is a known related-art technology that allows a projector to be attachable to and detachable from a pedestal. For example, in the projection system disclosed in JP-A-2006-208832, the pedestal apparatus includes a tuner that sends image and audio signals, and a coupler that electrically couples the projector and the tuner to each other, and sends the image and audio signals to the projector. 
     As described in JP-A-2006-208832, the projector, which can be detached from the pedestal and carried around, needs to have the settings thereof changed in accordance with the location where the projector is installed, and the setting operation imposes a burden on the user. 
     SUMMARY 
     An aspect of the present disclosure relates to a projector controlling method including causing a projector to project a projection image by using first setting values with the projector attached to a base apparatus that specifies a direction in which the projector projects projection light, and a position where the projector is installed, changing settings of the projector from the first setting values to second setting values when the projector is detached from the base apparatus, and changing the settings of the projector from the second setting values to the first setting values when the projector detects that the projector is attached to the base apparatus, and the set of first setting values and the set of second setting values each include a parameter relating to geometric correction of the projection image. 
     Another aspect at the present disclosure relates to a projection system including a projector including a projection apparatus that projects a projection image and a controller, and a base apparatus that specifies, when the projector is attached thereto, a direction in which the projector projects projection light and a position where the projector is installed. The controller causes the projection apparatus to project the projection image by using first setting values with the projector attached to the base apparatus, changes settings of the projector from the first setting values to second setting values when the projector is detached from the base apparatus, and changes the settings of the projector from the second setting values to the first setting values when the projector detects that the projector is attached to the base apparatus. The set of first setting values and the set of second setting values each include a parameter relating to geometric correction of the projection image. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exterior view of a projection system. 
         FIG.  2    is a block diagram showing an example of the configuration of a control system of the projection system. 
         FIG.  3    is a diagrammatic view showing an example of the configuration of data stored in a memory. 
         FIG.  4    describes an aspect in which the projection system is used. 
         FIG.  5    is a sequence diagram showing the action of the projection system according to the first embodiment. 
         FIG.  6    is a flowchart showing the action of the projector according to the first embodiment. 
         FIG.  7    is a sequence diagram showing the action of the projection system according to a second embodiment. 
         FIG.  8    is a sequence diagram showing the action of the projection system according to a third embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     1. First Embodiment 
     1-1. Configuration of Projection System 
       FIG.  1    is an exterior view of a projection system  100  according to a first embodiment and is also a perspective view of a projector  1  and a base apparatus  2  that form the projection system  100 . The projector  1  is attached to the base apparatus  2 , and the resultant structure forms the projection system  100 . 
     The projector  1  projects image light PL toward a projection target to form an image on the projection target. The projection of the image light PL performed by the projector  1  corresponds to displaying an image on the projection target. This action is called displaying in the following description. In the following description, the image includes video and still images. The image light PL is not limited to light that forms an image, and may, for example, be illumination light with which the space where the projector  1  is installed is illuminated. Specifically, the image light PL may be monochromatic light. 
     The projector  1  is attachable to and detachable from the base apparatus  2 . The base apparatus  2  is installed at the location where the projection system  100  is used. The base apparatus  2  is installed at a specific location where the projection system  100  is used with the base apparatus  2  oriented in a specific direction and located in a specific position. For example, the base apparatus  2  may be fixed in an immobile manner with the aid of screws, glue, or any other means. The base apparatus  2  may instead be fixed with the aid of a detachable component or a component that holds the base apparatus  2  so as not to allow the base apparatus  2  to readily move. 
     With the projector  1  attached to the base apparatus  2 , the projector  1  is placed at an upper surface  21  of the base apparatus  2 . The upper surface  21  is provided with a protrusion  22 . Coupling terminals  23  are disposed at the protrusion  22 . 
     A recess  45  is formed in the bottom surface of the projector  1 . The protrusion  22  fits into the recess  45  with the projector  1  placed at the upper surface  21 . The protrusion  22  having a rectangular columnar shape shown in  FIG.  1    is presented by way of example, and the shape and size of the protrusion  22  is arbitrarily changeable. The shape and size of the recess  45  only need to allow formation of a space capable of accommodating the protrusion  22 . 
     Coupling terminals  46  are disposed at the recess  45 . The coupling terminals  46  are in contact with the coupling terminals  23  with the projector  1  installed at the upper surface  21 . The coupling terminals  23  and  46  are electrical contacts made of metal or any other conductor. The coupling terminals  23  and  46 , when being in contact with each other, electrically couple the projector  1  to the base apparatus  2 . The projector  1  and the base apparatus  2  transmit an image signal via the coupling terminals  23  and  46 , as will be described later. 
     A switch  25  is disposed at the protrusion  22 . The switch  25  is a switch turned on when the switch  25  is pressed.  FIG.  1    shows an example in which the switch  25  is disposed at a side surface of the protrusion  22 , but there is no restriction on the position of the switch  25 . For example, the switch  25  may be disposed at the upper end of the protrusion  22 . When the protrusion  22  fits into the recess  45 , the switch  25  comes into contact with the inner surface of the recess  45 , so that the switch  25  is pressed and turned on. That is, the switch  25  functions as a sensor that detects that the projector  1  has been attached to the base apparatus  2 . The switch  25  corresponds to an example of a detecting section. 
     The switch  25  is an example of a sensor that detects that the projector  1  has been attached to the base apparatus  2 . For example, the switch  25  may be replaced with an optical or magnetic sensor that detects the proximity of the protrusion  22  to the projector  1 . 
     An image source  3  is coupled to the base apparatus  2 . The image source  3  is an apparatus that outputs an image signal. The image source  3  may be an image output device, for example, a media player and a digital camera. Examples of the image source  3  may include a personal computer, a smartphone, a tablet terminal, and other information processing terminals. 
     The base apparatus  2  includes a connector  24 . A connector  5  formed at the front end of a cable  4 , which electrically couples the base apparatus  2  to the image source  3 , can be coupled to the connector  24 . 
     The connectors  24  and  5  are connectors compliant with a standard for image signal transmission. Examples of the standard for image signal transmission may include HDMI (high-definition multimedia interface), USB-typeC (universal serial bus type C), DisplayPort, HDBaseT, and DVI (digital visual interface), and any other standard may also be used. HDMI, DisplayPort, and HDBaseT are registered trademarks. 
     The connectors  24  and  5  may each be an RCA terminal, a VGA terminal, an S terminal, a D terminal, or any other terminal via which an analog image signal is inputted and outputted. The base apparatus  2  may include a plurality of connectors  24 . In this case, the plurality of connectors  24  may differ from one another in terms of type and standard. 
     The base apparatus  2 , the image source  3 , and the cable  4  may be capable of transmission and reception of control signals between the base apparatus  2  and the image source  3 . The control signals are, for example, signals from the base apparatus  2  to the image source  3  that instruct the image source  3  to pause and resume image output. The present embodiment will be described with reference to a case where the cable  4  is an HDMI cable, and the connectors  24  and  5  comply with the HDMI standard. In the configuration described above, the base apparatus  2  and the image source  3  can transmit and receive the control signals via a CEC (consumer electronics control) link. 
     The projector  1  can display an image with the projector  1  attached to the base apparatus  2  or the projector  1  separated from the base apparatus  2 . The projector  1  includes a shifter  14 , which changes the direction in which the image light PL is projected. The shifter  14  shifts the image light PL by shifting a projection lens or any other component provided in the projector  1 . 
     In  FIGS.  1  and  4   , the latter of which will be described later, the projection direction of the projector  1  is indicated by a reference character LD. The projection direction LD is, for example, the direction of the optical axis of the image light PL that corresponds to the center axis thereof. The action of the shifter  14  can shift the projection direction LD, in which the image light PL is projected, in the upward direction indicated by a reference character UP, the downward direction indicated by a reference character DN, the leftward direction indicated by a reference character L, and the rightward direction indicated by a reference character R. 
     Shifting the image light PL with the aid of the shifter  14  in accordance with the relative positional relationship between the projection target and the projector  1  allows projection of a high quality image. For example, when the projection target is located in front of the projector  1 , the shifter  14  does not need to shift the image light PL. For example, when the projection target is located above the position where the projector  1  is installed, the shifter  14  can shift the image light PL in the direction UP to eliminate the need for geometric correction, or reduce the amount of deformation of the projected image due to geometric correction, whereby a higher quality image can be projected. 
     1-2. Configuration of Control System of Projection System 
       FIG.  2    is a block diagram showing an example of the configuration of a control system of the projection system  100 . The projection system  100  includes the projector  1  and the base apparatus  2 , as described above.  FIG.  2    shows a screen SC as the projection target, on which the projector  1  performs projection, but there is no restriction on the direction in which the projector  1  projects the image light PL or the projection target. 
     The projector  1  includes a projection apparatus  10 , which projects the image light PL, and a drive circuit  15 , which drives the projection apparatus  10 . The projection apparatus  10  includes a light source section  11 , a light modulator  12 , and a projection system  13 . The drive circuit  15  includes a light source drive circuit  16 , a light modulator drive circuit  17 , and an optical system drive circuit  18 . 
     The light source  11  is a lamp light source, such as a halogen lamp, a xenon lamp, and an ultrahigh-pressure mercury lamp, or a solid-state light source, such as an LED (light emitting diode) and a laser light source. The light source drive circuit  16  turns on and off the light source  11  under the control of a controller  50 . The light source drive circuit  16  adjusts the luminance of the light from the light source  11  under the control of the controller  50 . 
     The light modulator  12  includes light modulation devices that are not shown. The light modulation devices provided in the light modulator  12  include, for example, transmissive liquid crystal panels. The light modulation devices provided in the light modulator  12  may instead be reflective liquid crystal panels or digital micromirror devices (DMDs). 
     The light emitted by the light source  11  is separated by optical elements that are not shown but are disposed in the optical path between the light source  11  and the light modulator  12  into three kinds of color light, red light, green light, and blue light, which enter the light modulator  12 . The light modulation devices of the light modulator  12  modulate the three kinds of light to generate three kinds of image light PL. The three kinds of image light PL are combined with one another by a light combining system, such as a cross dichroic prism, and the combined image light PL exits toward the projection system  13 . 
     The light modulator drive circuit  17  is coupled to an image processing section  43 . The light modulator drive circuit  17  drives the light modulator  12  based on image signals generated by the image processing section  43  to draw images on a frame basis at the light modulation devices of the light modulator  12 . 
     The projection system  13  includes a lens, a mirror, and other components that bring the image light PL into focus on the screen SC. The image light PL is projected onto the screen SC via the projection system  13  and forms a projected image on the screen SC. The screen SC corresponds to an example of a projection surface. The projection system  13  includes a zooming mechanism and a focusing mechanism that adjusts the focusing, none of which is shown. 
     The optical system drive circuit  18  is coupled to the projection system  13 . The optical system drive circuit  18  operates the zooming mechanism and the focusing mechanism of the projection system  13 , and the shifter  14  under the control of the controller  50 . 
     The projector  1  includes an operation section  31 , a remote control light receiver  32 , an input interface  33 , a signal processing section  35 , a microphone  36  a loudspeaker  37 , a coupler  41 , a wireless communication section  42 , the image processing section  43 , and the controller  50 . The input interface  33 , the signal processing section  35 , the coupler  41 , the wireless communication section  42 , the image processing section  43 , and the controller  50  are coupled to each other via a bus  39  in a data communicable manner. 
     The operation section  31  includes a variety of buttons and switches provided at the surface of an enclosure of the projector  1 . For example, the operation section  31  includes a switch that instructs start of an audio recognition function. The operation section  31  generates an operation signal corresponding to the operation performed on any of the buttons and switches and outputs the operation signal to the input interface  33 . The input interface  33  includes a circuit that outputs the operation signal inputted from the operation section  31  to the controller  50 . 
     The remote control light receiver  32  includes a light receiving device that receives infrared light and receives an infrared signal transmitted from a remote control  7 . The remote control  7  transmits an infrared signal representing operation when a switch that is not shown but is provided at the remote control  7  is operated. The remote control light receiver  32  decodes the received infrared signal to generate an operation signal. The remote control light receiver  32  outputs the generated operation signal to the input interface  33 . The input interface  33  includes a circuit that outputs the operation signal inputted from the remote control light receiver  32  to the controller  50 . 
     An aspect in which a signal is transmitted from the remote control  7  and received by the remote control light receiver  32  is not limited to a specific aspect. The configuration in which the remote control  7  transmits the infrared signal to the remote control light receiver  32  is presented by way of example. For example, the remote control  7  and the remote control light receiver  32  may be configured to transmit and receive a signal by performing short-range wireless communication such as Bluetooth. In this case, the remote control light receiver  32  may be replaced with a communication processing circuit that performs short-range wireless communication such as Bluetooth. Bluetooth is a registered trademark. 
     The signal processing section  35  is coupled to the microphone  36  and the loudspeaker  37 . The microphone  36  collects sound from the space outside the enclosure of the projector  1 . The signal processing section  35  converts the audio collected by the microphone  36  into digital audio data and outputs the data to the controller  50 . The signal processing section  35  drives the loudspeaker  37  based on the digital audio data inputted from the controller  50  to cause the loudspeaker  37  to output audio. 
     The signal processing section  35  may include a digital-to-analog conversion circuit that converts the digital audio data into an analog audio signal. The signal processing section  35  may include an amplifier that amplifies the analog audio signal. 
     The coupler  41  is an interface apparatus including the coupling terminals  46  and an interface circuit that transmits and receives image signals via the coupling terminals  46 . The coupler  41  receives signals outputted by the base apparatus  2  with the coupling terminals  23  and  46  electrically continuous with each other. The signals outputted by the base apparatus  2  include image signals and control signals. The image signals outputted by the base apparatus  2  may be signals accompanied by or including audio signals. The coupler  41  further transmits control signals to the base apparatus  2  under the control of the controller  50 . 
     The wireless communication section  42  is a communication apparatus that performs wireless communication. The wireless communication section  42  includes, for example, an antenna, an RF (radio frequency) circuit, and a baseband circuit. The wireless communication section  42  transmits and receives image signals, audio signals, other control signals, and the like via the wireless communication. The wireless communication section  42  performs, for example, WirelessHD, MIracast, Wi-Fi, Bluetooth, and other types of communication. WirelessHD, MIracast, and Wi-Fi are registered trademarks. 
     The wireless communication section  42  performs the wireless communication, for example, with a wireless instrument  8 . There are no restrictions on the type of the wireless instrument  8 . For example, the wireless instrument  8  may be a loudspeaker that receives an audio signal from the projector  1  over Bluetooth communication. The wireless instrument  8  may instead be an image supplier that wirelessly transmits an image signal to the projector  1 . 
     The image processing section  43  selects an image source under the control of the controller  50 . Examples of the source available to the projector  1  may include image signals received by the coupler  41 , image signals received by the wireless communication section  42 , and image data stored in a memory  53 . 
     The image processing section  43  acquires image data from the selected source and performs image processing on the image data. The image processing performed by the image processing section  43  includes, for example, resolution conversion, geometric correction, digital zooming, and image correction for adjustment of the hue and brightness of an image. As an example, the image processing section  43  in the present embodiment performs at least geometric correction. The image processing section  43  performs geometric correction on an image to be projected by the projection apparatus  10  in accordance with a correction parameter inputted from the controller  50 . 
     The image processing section  43  generates an image signal based on the image data having undergone the image processing and outputs the image signal to the light modulator drive circuit  17 . A frame memory that is not shown may be coupled to the image processing section  43 . The frame memory is formed, for example, of an SDRAM (synchronous dynamic random access memory). In this case, the image processing section  43  loads image data acquired from the source in the frame memory. The image processing section  43  performs the image processing on the image data loaded in the frame memory. 
     The image processing section  43  can be formed, for example, of an integrated circuit. The integrated circuit is based, for example, on LSI (large scale integration). More specifically, the image processing section  43  is formed, for example, of an ASIC (application specific integrated circuit) or a PLC (programmable logic device). The PLD includes, for example, an FPGA (field-programmable gate array). An analog circuit may form part of the configuration of the integrated circuit, or the combination of a processor and an integrated circuit may be used. The combination of a processor and an integrated circuit is called, for example, a microcontroller (MCU), a SoC (System-on-a-chip), a system LSI, and a chipset. 
     The projector  1  includes a battery  49 . The battery  49  has a built-in secondary battery, such as a lithium ion battery or a metal hydride battery, and supplies each portion of the projector  1  with electric power from the secondary battery. The projector  1  includes a charging connector that is not shown and charges the battery  49  with electric power externally inputted via the charging connector. The projector  1  can use the electric power from the battery  49  to operate the portions of the projector  1  including the projection apparatus  10 , the drive circuit  15 , the wireless communication section  42 , the image processing unit  43 , and the controller  50 . Specifically, the projector  1  can project the image light PL by using the electric power charged in the battery  49 . 
     The battery  49  is coupled to the coupler  41 . With the base apparatus  2  coupled to the coupler  41 , the coupler  41  receives electric power supplied from the base apparatus  2  and supplies the battery  49  with the electric power for charging. Specifically, some of the terminals of the coupler  41  are power feeding terminals that supply the projector  1  with the electric power from the base apparatus  2 , and the coupler  41  charges the battery  49  with the electric power supplied via those of the coupling terminals  46 . 
     The controller  50  includes a processor  51  and the memory  53 . The memory  53  is a storage apparatus that stores in a nonvolatile manner a program executed by the processor  51  and data processed by the processor  51 . The memory  53  is formed of a magnetic storage apparatus, a semiconductor storage element such as a flash ROM (read only memory), or any other type of nonvolatile storage apparatus. The memory  53  may include a RAM (random access memory) that forms a work area for the processor  51 . The memory  53  stores data to be processed by the controller  50  and a control program  55  executed by the processor  51 . 
     The processor  51  is formed, for example, of a CPU (central processing unit) or an MPU (micro-processing unit). The processor  51  may be formed of a single processor, or a plurality of processors may function as the processor  51 . The processor  51  may be formed of an SoC integrated with part or entirety of the memory  53  and/or another circuit. The processor  51  may instead be formed of the combination of a CPU that executes a program and a DSP (digital signal processor) that performs predetermined arithmetic processing, as described above. The entire functions of the processor  51  may be implemented in hardware or may be achieved by using a programmable device. The processor  51  may also provide the function of the image processing section  43 . That is, the function of the image processing section  43  may be performed by the processor  51 . 
     The processor  51  controls the portions of the projector  1  by executing the control program  55  stored in the memory  53 . 
     The processor  51  causes the image processing section  43  to select a source, and causes the image processing section  43  to acquire image data from the selected source. The processor  51  controls the drive circuit  15  to cause the projection apparatus  10  to project the image light PL to display an image based on the image signal outputted by the image processing section  43 . 
     The memory  53  stores, for example, image data. When the image processing section  43  selects the image data in the memory  53  as the source, an image based on the image data stored in the memory  53  is projected by the projection apparatus  10 . 
     The memory  53  stores first setting values  56  and second setting values  57 . The first setting values  56  include a variety of setting values used with the base apparatus  2  coupled to the coupler  41 . The second setting values  57  include a variety of setting values used with the projector  1  separated from the base apparatus  2 . The memory  53  corresponds to an example of a first storage section. 
     When the coupling terminals  23  of the base apparatus  2  are electrically coupled to the coupler  41 , the processor  51  causes the coupler  41  to receive an image signal via wired communication. 
     The processor  51  monitors whether or not the base apparatus  2  is coupled to the coupler  41  from the state in which the base apparatus  2  is not coupled to the coupler  41 , that is, with the projector  1  is not attached to the base apparatus  2 . When the processor  51  detects that the base apparatus  2  has been coupled to the coupler  41 , the processor  51  sets a variety of settings, including the projection apparatus  10 , of the projector  1  by using the setting values in the first setting values  56 . 
     The processor  51  monitors whether or not the base apparatus  2  is separated from the coupler  41  from the state in which the base apparatus  2  is coupled to the coupler  41 , that is, with the projector  1  is attached to the base apparatus  2 . When the processor  51  detects that the base apparatus  2  has been separated from the coupler  41 , the processor  51  sets the variety of settings, including the projection apparatus  10 , of the projector  1  by using the setting values in the second setting values  57 . 
       FIG.  3    is a diagrammatic view showing an example of the configuration of the data stored in the memory  53 . 
     The first setting values  56  include a base ID  560 , a lens shift setting value  561 , a zooming setting value  562 , a focusing setting value  563 , a geometric correction parameter  564 , a volume setting value  565 , a brightness setting value  566 , and a wireless connection setting  567 . The base ID  560  is identification information that identifies the base apparatus  2  and is assigned to each individual base apparatus  2  in advance. 
     The second setting values  57  include a lens shift setting value  571 , a zooming setting value  572 , a focusing setting value  573 , a geometric correction parameter  574 , a volume setting value  575 , a brightness setting value  576 , and a wireless connection setting  577 . The lens shift setting values  561  and  571  include setting values of the same type. The setting value included in the lens shift setting value  561  and the setting value included in the lens shift setting value  571  may be the same or different from each other. The same holds true for the zooming setting values  562  and  572 , the focusing setting values  563  and  573 , and the geometric correction parameters  564  and  574 . The same also holds true for the volume setting values  565  and  575 . The same further holds true for the brightness setting values  566  and  576  and the wireless connection settings  567  and  577 . 
     The lens shift setting values  561  and  571  are setting values that specify the position to which the projection direction LD is shifted by the shifter  14 . The processor  51  causes the shifter  14  to act by controlling the optical system drive circuit  18  based on the lens shift setting value  561  or  571 . The shifter  14  thus shifts the projection direction LD in the direction specified by the lens shift setting value  561  or  571  by the amount specified by the lens shift setting value  561  or  571 . 
     The zooming setting values  562  and  572  are setting values that specify the state of the zooming mechanism of the projection system  13 . The processor  51  causes the zooming mechanism to act by controlling the optical system drive circuit  18  based on the zooming setting value  562  or  572 . The zooming mechanism thus enlarges or reduces the image light PL at the magnification specified by the zooming setting value  562  or  572 . 
     The focusing setting values  563  and  573  are setting values that specify the state of the focusing mechanism of the projection system  13 . The processor  51  causes the focusing mechanism to act by controlling the optical system drive circuit  18  based on the focusing setting value  563  or  573 . The focusing mechanism thus adjusts the focus of the image light PL in accordance with the focusing setting value  563  or  573 . 
     The geometric correction parameters  564  and  574  each include a parameter of the geometric correction performed by the image processing section  43 . The processor  51  sets the geometric correction parameter  564  or  574  in the image processing section  43 . The image processing section  43  performs the geometric correction in accordance with the geometric correction parameter  564  or  574  set by the processor  51 . 
     The first setting values  56  include one or more of the lens shift setting value  561 , the zooming setting value  562 , the focusing setting value  563 , and the geometric correction parameter  564 . The second setting values  57  include one or more of the lens shift setting value  571 , the zooming setting value  572 , the focusing setting value  573 , and ole geometric correction parameter  574 . 
     The first setting values  56  may or may not include the volume setting value  565 , the brightness setting value  566 , or the wireless connection setting  567 . In this case, the second setting values  57  may or may not include the volume setting value  575 , the brightness setting value  576 , or the wireless connection setting  577 . 
     The volume setting values  565  and  575  are setting values that specify the volume of the audio outputted by the projector  1 . The volume setting values  565  and  575  are used when the projector  1  outputs audio via the loudspeaker  37  or when the wireless instrument  8  wirelessly connected to the wireless communication section  42  is a loudspeaker and the wireless instrument  8  outputs audio. The processor  51  controls the signal processing section  35  based on the volume setting value  565  or  575  to set the output volume of the loudspeaker  37  at the volume specified by the volume setting value  565  or  575 . When the wireless instrument  8  wirelessly connected to the wireless communication section  42  is a loudspeaker, the processor  51  transmits a control signal from the wireless communication section  42  to the wireless instrument  8  based on the volume setting value  565  or  575 , and causes the wireless instrument  8  to output audio at the volume specified by the volume setting value  565  or  575 . 
     The brightness setting values  566  and  576  are setting values that specify the brightness of an image projected by the projection apparatus  10 . The processor  51  controls the light source drive circuit  16  based on the brightness setting value  566  or  576  to adjust the amount of the image light PL in such a way that the projected image has the brightness specified by the brightness setting value  566  or  576 . 
     The wireless connection settings  567  and  577  include setting values relating to the function of connecting the wireless communication section  42  to the wireless instrument  8  via wireless communication. The wireless connection setting  567  sets the action of the wireless communication section  42  in the state in which the projector  1  is coupled to the base apparatus  2 . The wireless connection setting  577  sets the action of the wireless communication section  42  in the state in which the projector  1  is not coupled to the base apparatus  2 . For example, the wireless connection settings  567  and  577  specify whether or not the wireless communication section  42  is allowed to be connected to the wireless instruments  8 , identification information that identifies the wireless instrument  8  to which the wireless communication section  42  is allowed to be connected, and the type of the wireless instrument  8  to which the wireless communication section  42  is allowed to be connected. The wireless connection settings  567  and  577  further include, for example, the number of wireless instruments  8  to which the wireless communication section  42  is connected. 
     The identification information that identifies the wireless instrument  8  contained in the wireless connection settings  567  and  577  may be information that allows identification of an individual wireless instrument  8 . Examples of the identification information that identifies the wireless instrument  8  may include a Bluetooth ID and a device ID. 
     The set of first setting values  56  is associated with the base ID  560 . The memory  53  may be configured to store a plurality of sets of first setting values  56 . In this case, the plurality of sets of first setting values  56  each include a unique base ID  560  different from the others. When the processor  51  detects that the base apparatus  2  has been coupled to the coupler  41 , the processor  51  acquires the base ID of the base apparatus  2  and selects the set of first setting values  56  including the acquired base ID. The processor  51  sets the portions, including the projection apparatus  10 , of the projector  1  based on the selected set of first setting values  56 . 
     The plurality of sets of first setting values  56  stored by the memory  53  include setting values of the same type. The setting values included in the plurality sets of first setting values  56  may be the same value or different values, with the exception of the base ID  560 . 
     In the state in which the base apparatus  2  is coupled to the projector  1 , the processor  51  sets the first setting values  56  in the portions of the projector  1  and causes the projection apparatus  10  to project an image. In the state in which the base apparatus  2  is not coupled to the projector  1 , the processor  51  sets the second setting values  57  stored by the memory  53  in the portions of the projector  1  and causes the projection apparatus  10  to project an image. 
       FIG.  4    describes an aspect in which the projection system  100  is used and shows an example of an installation room  400 , where the projection system  100  is used. 
       FIG.  4    shows two specific examples of the installation room  400 : an installation room  400 A, where a base apparatus  2 A is installed; and an installation room  400 B, where a base apparatus  2 B is installed. The base apparatuses  2 A and  2 B are examples of the base apparatus  2 . 
     A screen SC 1  is installed at one wall surface of the installation room  400 A. In the installation room  400 A, a desk  411  is installed in a position where the desk  411  directly faces the screen SC 1 , and the base apparatus  1 A is fixed to the upper surface of the desk  411 . The base apparatus  2 A may be fixed to the desk  411  in an immobile manner or may be placed on the desk  411 . 
     A screen SC 2  is installed at one wall surface of the installation room  400 B. In the installation room  400 B, a cabinet  412  is installed in a position where the cabinet  412  directly faces the screen SC 2 , and the base apparatus  2 B is fixed to the upper surface of the cabinet  412 . The base apparatus  2 B may be fixed to the cabinet  412  in an immobile manner or may be placed on the cabinet  412 . 
     The base apparatus  2  specifies the direction in which the projector  1  projects the image light PL and the position where the projector  1  is installed, as shown in  FIG.  1   . 
     Now, a case where the projector  1  is installed in the installation room  400 A and the projector  1  projects the image light PL onto the screen SC 1  is compared with a case where the projector  1  is installed in the installation room  400 B and the projector  1  projects the image light PL onto the screen SC 2 . The distance between the screen SC 1  and the desk  411  is longer than the distance between the screen SC 2  and the cabinet  412 . The height of the desk  411  differs from the height of the cabinet  412 . 
     When the projector  1  is installed at the base apparatus  2 A, the projection apparatus  10  is preferably set in accordance with the distance between the base apparatus  2 A and the screen SC 1  in the installation room  400 A, the relative height relationship between the base apparatus  2 A and the screen SC 1 , the size of the installation room  400 A, and other factors. Specifically, a high quality image can be projected onto screen SC 1  by appropriately setting the setting value of the shifter  14 , and the zooming setting, the focusing setting, the geometric correction parameter, and the brightness of the image light PL in the projection apparatus  10 . The same holds true for the installation room  400 B. 
     In the projector  1  according to the present embodiment, the first setting values  56  suitable for the installation room  400 A and the first setting values  56  suitable for the installation room  400 B are stored in the memory  53 . The first setting values  56  suitable for the installation room  400 A include setting values adapted to the position where the base apparatus  2 A is installed in correspondence with the base ID  560  of the base apparatus  2 A. The setting values specifically include the lens shift setting value  561 , the zooming setting value  562 , the focusing setting value  563 , the geometric correction parameter  564 , and the brightness setting value  566 . The first setting values  56  suitable for the installation room  400 B include the variety of setting values in association with the base ID  560  of the base apparatus  2 B. 
     When the projector  1  is coupled to the base apparatus  2 A, the processor  51  sets the setting values in the first setting values  56  associated with the base ID  560  of the base apparatus  2 A in the projector  1 . The projector  1  can thus operate the projection apparatus  10  at the settings suitable for the relative positional relationship between the projector  1  and the screen SC 1  in the installation room  400 A to project a high quality image. The same holds true for the case where the projector  1  is coupled to the base apparatus  2 B. 
     A loudspeaker  81  is installed in the installation room  400 A. A loudspeaker  82  is installed in the installation room  400 B. The loudspeakers  81  and  82  are examples of the wireless instrument  8 . The wireless connection setting  567  associated with the base apparatus  2 A contains information that allows the wireless communication section  42  to couple the projector  1  to the loudspeaker  81 . The wireless connection setting  567  associated with the base apparatus  2 B contains information that allows the wireless communication section  42  to couple the projector  1  to the loudspeaker  82 . 
     When the projector  1  is coupled to the base apparatus  2 A, the processor  51  couples the wireless communication section  42  to the loudspeaker  81  based on the wireless connection setting  567  associated with the base ID  560  of the base apparatus  2 A. The projector  1  can thus be wirelessly connected to the loudspeaker  81  via the wireless communication section  42  and output audio from the loudspeaker  81  by transmitting audio data to the loudspeaker  81 . The volume of the audio outputted by the loudspeaker  81  is set based on the volume setting value  565 . The projector  1  can therefore output audio at a predetermined volume from the loudspeaker  81  by causing the processor  51  to set the wireless communication section  42  based on the volume setting value  565  and the wireless connection setting  567 . When the projector  1  is coupled to the base apparatus  2 B, the processor  51  couples the wireless communication section  42  to the loudspeaker  82  by using the volume setting value  565  and the wireless connection setting  567  associated with the base ID  560  of the base apparatus  2 B. 
     Returning back to  FIG.  2   , the base apparatus  2  includes a first transmitter  201 , a signal input section  203 , a power source circuit  205 , and a transmission control section  210 . 
     The first transmitter  201  is an interface apparatus including the coupling terminals  23  and an interface circuit that transmits and receives image signals via the coupling terminals  23 . The first transmitter section  201  transmits an image signal to the projector  1  with the coupling terminals  23  and  46  electrically continuous with each other. 
     The first transmitter  201  is coupled to the power source circuit  205 . The power source circuit  205  is coupled to a power source  6  external to the base apparatus  2 . The power source circuit  205  outputs a DC current having a predetermined voltage to the first transmitter  201  based on the electric power supplied from the power source  6 . The first transmitter  201  outputs the current inputted from the power source circuit  205  to the coupler  41  via the coupling terminals  23  under the control of the transmission control section  210 . 
     The power source  6  is, for example, a commercial AC power source. In this case, the power source circuit  205  may be configured to include a conversion circuit or a voltage conversion circuit that converts an AC current to a DC current having a predetermined voltage. The power source  6  may instead be an AC adapter that converts commercial AC electric power into a DC current having a predetermined voltage and outputs the converted DC current. In this case, the power source circuit  205  may be configured to include no conversion circuit that converts an AC current into a DC current having a predetermined voltage. 
     The signal input section  203  is an interface apparatus including the connector  24  and an interface circuit that receives an image signal via the connector  24 . The signal input section  203  receives the image signal outputted by the image source  3  through the cable  4  via the connector  24 . The image signal transmitted by the image source  3  does not necessarily have a specific signal format, may have a signal format compliant with any of the variety of standards described above or a non-standardized signal format. The image signal transmitted by the image source  3  may include an audio signal. 
     The transmission control section  210  is coupled to the first transmitter  201  and the signal input section  203 . 
     The transmission control section  210  includes a processor  211  and a memory  213 . The memory  213  is a storage apparatus that stores in a nonvolatile manner a program executed by the processor  211  and data processed by the processor  211 . The memory  213  is formed of a magnetic storage apparatus, a semiconductor storage element, such as a flash ROM, or any other nonvolatile storage apparatus. The memory  213  may include a RAM that forms a work area used by the processor  211 . The memory  213  stores data to be processed by the transmission control section  210  and a control program  215  executed by the processor  211 . 
     The processor  211  is formed, for example, of a CPU, an MPU, or a microcomputer. The processor  211  may be formed of a single processor, or a plurality of processors may function as the processor  211 . The processor  211  may be formed of an SoC integrated with part or entirety of the memory  213  and/or another circuit. Furthermore, the entire functions of the processor  211  may be implemented in hardware or may be achieved by using a programmable device. 
     The processor  211  controls each portion of the base apparatus  2  by executing the control program  215  stored in the memory  213 . 
     The processor  211  receives the image signal from the signal input section  203  and generates an image signal to be transmitted to the projector  1  based on the received image signal. The image signal transmitted by the base apparatus  2  to the projector  1  may be the same as the image signal received from the image source  3 . The processor  211  may generate the image signal to be transmitted to the projector  1  by converting the frame frequency, the resolution, and the transmission rate of the image signal received from the image source  3 . 
     When the coupling terminals  23  are wired to the coupling terminals  46 , the processor  211  controls the first transmitter  201  to couple the coupler  41  of the projector  1  to the first transmitter  201 . The processor  211  controls the first transmitter  201  to cause the first transmitter  201  to output the image signal to the projector  1 . 
     The switch  25  is coupled to the transmission control section  210 . The switch  25  is turned on when the projector  1  is coupled to the base apparatus  2  and turned off when the projector  1  is separated from the base apparatus  2 . The processor  211  detects that the projector  1  has been coupled to the base apparatus  2  and that the projector  1  has been separated from the base apparatus  2  based on the state of the switch  25 . 
     At least one of the projector  1  and the base apparatus  2  can sense that the projector  1  and the base apparatus  2  have been coupled to each other and that the projector  1  and the base apparatus  2  have been separated from each other. 
     Specific aspects in which the projector  1  detects that the projector  1  and the base apparatus  2  have been coupled to each other and that the projector  1  and the base apparatus  2  have been separated from each other may include Specific Examples 1 to 4. 
     Specific Example 1: When an image signal, a control signal, or any other signal is inputted to the coupler  41 , the processor  51  detects that the base apparatus  2  has been coupled to the coupler  41 . When the signal being inputted to the coupler  41  is disrupted, the processor  51  detects that the coupler  41  and the base apparatus  2  has been decoupled from each other, that is, the projector  1  is separated from the base apparatus  2 . In detail, when the electric signal being inputted to the coupling terminals  46  of the coupler  41  stops and the period for which the electric signal stops becomes longer than a predetermined period or a timeout occurs, the processor  51  detects that the wired coupling has been decoupled. In this case, when the electric signal being inputted to the coupling terminals  46  of the coupler  41  stops and the period for which the electric signal stops becomes longer than the predetermined period or a timeout occurs, the processor  51  detects that the wired coupling has been decoupled. 
     Specific Example 2: The processor  51  monitors the electrical continuity between the coupling terminals  23  and  46 . When the coupling terminals  23  and  46  are electrically coupled to each other, the processor  51  detects that the base apparatus  2  has been coupled to the coupler  41 . When the processor  51  detects that the electrical continuity between the coupler  41  and the coupling terminals  23  has been disrupted, the processor  51  detects that the projector  1  has been separated from the base apparatus  2 . Employing the approach described above and further employing, for example, a configuration in which the coupling terminals  23  and  46  are provided with contacts for checking electrical continuity allows the processor  51  to sense the disruption of the wired coupling more readily. 
     Specific Example 3: When the electric power supplying to the coupler  41  starts, the processor  51  detects that the base apparatus  2  has been coupled to the coupler  41 . When the electric power supplying to the coupler  41  is disrupted, the processor  51  detects that the projector  1  has been separated from the base apparatus  2 . 
     Specific Example 4: The projector  1  is configured to sense physical separation of the protrusion  22  of the base apparatus  2  from the recess  45  of the projector  1 . Specifically, a sensor that detects engagement with the protrusion  22  is provided in the recess  45 . The sensor is, for example, a switch-type sensor similar to the switch  25 , or an optical or magnetic sensor that detects the proximity of the protrusion  22  to the projector  1 . The processor  51  detects that the projector  1  has been coupled to the base apparatus  2  and that the projector  1  has been separated from the base apparatus  2  based on the value detected by the sensor. 
     Instead of the above, for example, a user may operate the operation section  31  or the remote control  7  to inform the projector  1  that the projector  1  has been attached to the base apparatus  2 . In this case, the projector  1  accepts the operation via the operation section  31  or the remote control  7  and can therefore quickly sense that the projector  1  has been attached to the base apparatus  2 . In this case, at least one of the operation section  31  and the remote control  7  corresponds to an example of an operation section. 
     Specific aspects in which the base apparatus  2  detects that the projector  1  and the base apparatus  2  have been coupled to each other and that the projector  1  and the base apparatus  2  have been separated from each other may include Specific Examples 5 to 8. 
     Specific Example 5: The processor  211  detects that the projector  1  has been separated from the base apparatus  2  based on whether or not there is a response to the transmission of an image signal from the first transmitter  201 . For example, when the first transmitter  201  transmits an image signal, the projector  1  transmits a response to the first transmitter  201  in a frame cycle or a packet cycle, or at any other timing. When the electrical signal being inputted from the projector  1  to the coupling terminals  23  stops and the period for which the electrical signal stops becomes longer than a predetermined period or a timeout occurs, the processor  211  detects that the projector  1  has been separated from the base apparatus  2 . 
     Specific Example 6: The processor  211  monitors the electrical continuity between the coupling terminals  23  and  46 . When the coupling terminals  23  and  46  are electrically coupled to each other, the processor  211  detects that the base apparatus  2  has been coupled to the coupler  41 . When the processor  211  detects that the electrical continuity between the coupler  41  and the coupling terminals  23  has been disrupted, the processor  211  detects that the projector  1  has been separated from the base apparatus  2 . Employing the approach described above and further employing, for example, the configuration in which the coupling terminals  23  and  46  are provided with contacts for checking electrical continuity allows the processor  211  to sense the disruption of the wired coupling more readily. 
     Specific Example 7: The processor  211  detects that the projector  1  has been coupled to the base apparatus  2  and the projector  1  has been separated from the base apparatus  2  based on the state of a load coupled to a terminal, out of the coupling terminals  23 , to which electric power is supplied from the first transmitter  201 . 
     Specific Example 8: The processor  211  detects that the projector  1  has been coupled to the base apparatus  2  and the projector  1  has been separated from the base apparatus  2  based on the state of the switch  25 . 
     The memory  213  provided an the base apparatus  2  stores a base ID  216 . The base ID  216  is an identification information that allows identification of an individual base apparatus  2 . When the projector  1  is coupled to the base apparatus  2 , the processor  211  transmits the base ID  216  to the projector  1  via the first transmitter  201 . 
     In the first embodiment and a second embodiment, the latter of which will be described later, the base apparatus  2  detects that the projector  1  has been coupled to the base apparatus  2 . The case where the base apparatus  2  performs the action in Specific Example 8 described above will be described by way of example, but any of the methods in Specific Examples 5 to 7 is also applicable. In a third embodiment, which will be described later, the projector  1  detects that the projector  1  has been coupled to the base apparatus  2 . The specific configuration in this case may be any of the configurations in Specific Examples 1 to 4 described above. In the first to third embodiments, the projector  1  and the base apparatus  2  mutually sense that the projector  1  has been separated from the base apparatus  2 . The specific configuration in this case may be any of the configurations in Specific Examples 1 to 8 described above. 
     1-3. Action of Projection System 
       FIG.  5    is a sequence diagram showing the action of the projection system  100 .  FIG.  6    is a flowchart showing the action of the projector  1 . The action of the projection system  100  will be described with reference to  FIGS.  5  and  6   . The action shown in  FIG.  5    is the action performed when the projector  1  is not attached to the base apparatus  2  and the projector  1  is then attached to the base apparatus  2 . In  FIG.  5   , the controller  50  carries out the processes in steps SA 11  to SA 21 , and the transmission control section  210  carries out the processes in steps SB 11  to SB 13 . 
     In step SB 11 , the base apparatus  2  detects that the projector  1  is coupled thereto. A specific detecting method in step SB 11  can be any of those in Specific Examples 5 to 8 described above. In step SB 12 , the base apparatus  2  transmits a control signal containing the base ID  216  to the projector  1  from the first transmitter  201 . 
     In step SA 11 , the projector  1  receives the control signal transmitted by the base apparatus  2  to sense that the projector  1  has been coupled to the base apparatus  2 . In step SA 12 , the projector  1  acquires the base ID contained in the control signal transmitted by the base apparatus  2 . In step SA 11 , the projector  1  may sense that the projector  1  has been coupled to the base apparatus  2  by executing any of the methods in Specific Examples 1 to 4 described above. 
     In step SA 13 , the projector  1  acquires from the memory  53  the first setting values  56  including the base ID acquired in step SA 12 . That is, the projector  1  acquires the setting values associated with the base ID acquired in step SA 12 . 
     In step SA 14 , the projector  1  changes the settings of the portions thereof including the projection apparatus  10  based on the first setting values  56  acquired in step SA 13 . 
     In step SA 15 , the projector  1  is coupled to the wireless instrument  8  via the wireless communication section  42  in accordance with the wireless connection setting  567  included in the first setting values  56  acquired in step SA 13 . 
     In step SB 13 , the base apparatus  2  starts transmitting an image signal to the projector  1  via the coupler  41 . The image signal transmitted by the base apparatus  2  may be a signal containing or accompanied by an audio signal. 
     In step SA 16 , the projector  1  starts receiving the image signal transmitted by the base apparatus  2 . In step SA 17 , the projector  1  starts displaying based on the image signal received from the base apparatus  2 . In a case where the projector  1  receives an audio signal from the base apparatus  2 , the projector  1  starts outputting audio in step SA 17 . 
     In step SA 18 , the projector  1  evaluates whether or not the operation of instructing a change in the settings relating to the action of the projector  1  has been performed, for example, via the operation section  31  or the remote control  7 . When the operation of instructing a change in the settings is performed (YES in step SA 18 ), the projector  1  transitions to step SA 19  to update the first setting values  56  in accordance with the operation. The projector  1  then transitions to step SA 20  to evaluate whether or not the operation section  31 , the remote control  7 , or any other component has been operated to instruct termination of the displaying. When no instruction of termination of the displaying has been issued (NO in step SA 20 ), the projector  1  returns to step SA 18 . When the instruction of termination of the displaying has been issued (YES in step SA 20 ), the projector  1  transitions to step SA 21  to terminate the displaying and end the present procedure. In the case where the projector  1  has started outputting audio in step SA 17 , the projector  1  stops outputting the audio in step SA 21 . When the projector determines in step SA 18  that no operation of instructing a change in the settings has been performed (NO in step SA 18 ), the projector  1  does not execute step SA 19  but transitions to step SA 20 . 
     The action shown in  FIG.  6    is the action of the projector  1  performed when the projector  1  is attached to the base apparatus  2  and the projector  1  is then separated from the base apparatus  2 . The processes in steps SA 31  to SA 41  in  FIG.  6    are carried out by the controller  50 . 
     In step SA 31 , the projector  1  detects that the projector  1  has been separated from the base apparatus  2 . How the projector  1  specifically detects its separation from the base apparatus  2  can be any of the methods described in Specific Examples 1 to 4 described above. 
     The projector  1  transitions to step SA 32  to stop the displaying performed by the projection apparatus  10 . In step SA 33 , the projector  1  acquires the second setting values  57  stored by the memory  53  and transitions to step SA 34  to change the settings of the portions of the projector  1  based on the second setting values  57 . The process in step SA 34  changes the settings of the projection apparatus  10  and the image processing section  43  to the settings according to the second setting values  57 . 
     In step SA 35 , the projector  1  disconnects the connection to the wireless instrument  8  connected based on the wireless connection setting  567 . 
     The projector then evaluates in step SA 36  whether or not the operation section  31  or the remote control  7  has been operated to instruct start of the displaying. When the start of the displaying is instructed (YES in step SA 36 ), the projector  1  transitions to step SA 37  to start the displaying performed by the projection apparatus  10  and transitions to step SA 38 . In step SA 37 , the projector  1  displays an image based, for example, on the image data stored in the memory  53 . In step SA 37 , the projector  1  may start outputting audio while starting the displaying. 
     When the start of the displaying has not been instructed (NO in step SA 36 ), the projector  1  transitions to step SA 38 . 
     In step SA 38 , the projector  1  evaluates whether or not the operation of instructing a change in the settings relating to the action of the projector  1  has been performed, for example, via the operation section  31  or the remote control  7 . When the operation of instructing a change in the settings has been performed (YES in step SA 38 ), the projector  1  transitions to step SA 39  to update the second setting values  57  in accordance with the operation. The projector  1  then transitions to step SA 40  to evaluate whether the operation section  31 , the remote control  7 , or any other component has been operated to instruct termination of the displaying. When termination of the displaying has not been instructed (NO in step SA 40 ), the projector  1  returns to step SA 38 . When termination of the displaying has been in (YES in step SA 40 ), the projector  1  transitions to step SA 41  to terminate the displaying and end present procedure. In the case where the projector  1  has started outputting audio in step SA 37 , the projector  1  stops outputting the audio in step SA 41 . When the projector determines in step SA 38  that no operation of instructing a change in the settings has been performed (NO in step SA 36 ) , the projector  1  does not execute step SA 39  but transitions to step SA 40 . 
     1-4. Effects of Embodiment 
     As described above, the method for controlling the projector  1  described in the first embodiment includes causing the projector  1  to project a projection image by using the first setting values  56  with the projector  1  attached to the base apparatus  2 , which specifies the direction in which the projector  1  projects the image light PL and the position where the projector  1  is installed. The method includes changing the settings of the projector  1  from the first setting values  56  to the second setting values  57  when the projector  1  is detached from the base apparatus  2 . The method includes changing the settings of the projector  1  from the second setting values  57  to the first setting values  56  when the projector  1  detects that the projector  1  has been attached to the base apparatus  2 . The set of first setting values  56  and the set of second setting values  57  each include a parameter relating to the geometric correction of the projected image. 
     Therefore, when the projector  1  is attached to the base apparatus  2 , the settings of the projector  1  are made based on the first setting values  56  including the parameter relating to geometric correction in correspondence with the direction in which the projector  1  projects the image light PL and the position where the projector  1  is installed. When the projector  1  is detached from the base apparatus  2 , the settings of the projector  1  are made based on the second setting values  57 . The frequency of the operation of changing the settings of the projection apparatus  10  including the geometric correction parameter in accordance with the location where the projector  1  is used can thus be reduced. The settings of the projector  1 , which can be detached from the base apparatus  2  and carried around, can therefore be readily changed in accordance with the location where the projector  1  is installed. 
     The method for controlling the projector  1  may include detecting that the projector  1  has been attached to the base apparatus  2  when the projector  1  receives a control signal outputted by the base apparatus  2  in response to the attachment of the projector  1  to the base apparatus  2  sensed by the switch  25  provided in the base apparatus  2 . In this case, the base apparatus  2  detects that the projector  1  has been attached to the base apparatus  2 , and the base apparatus  2  transmits a control signal to the projector  1 , so that the projector  1  can sense that the projector  1  has been attached to the base apparatus  2 . The base apparatus  2  therefore performs operation of outputting the control signal to allow the projector  1  to quickly sense that the projector  1  has been attached to the base apparatus  2 . 
     The method for controlling the projector  1  may include detecting that the projector  1  has been attached to the base apparatus  2  when the projector detects that electric power is supplied to the projector  1  from the base apparatus  2 . In this case, the projector  1  can quickly sense that the projector  1  has been attached to the base apparatus  2 . 
     The method for controlling the projector  1  may include causing the projector  1  to sense that the projector  1  has been attached to the base apparatus  2  when the projector  1  detects that an image signal is inputted to the projector  1  from the base apparatus  2 . In this case, the base apparatus  2  performs operation of outputting the image signal to allow the projector  1  to quickly sense that the projector  1  has been attached to the base apparatus  2 . 
     The method for controlling the projector  1  may include detecting that the projector  1  has been attached to the base apparatus  2  when the projector  1  detects operation performed on the operation section  31  or the remote control  7  provided in the projector  1 . Specifically, the user attaches the projector  1  to the base apparatus  2 , and then operates the operation section  31  or the remote control  7  to perform operation of indicating that the projector  1  has been attached to the base apparatus  2 . The projector  1  can therefore make settings corresponding to the fact that the projector  1  has been attached to the base apparatus  2  based on the user&#39;s operation. 
     The method for controlling the projector  1  may include storing the first setting values  56  in the memory  53  provided in the projector  1  and updating the first setting values  56  stored by the first storage section when the projector  1  accepts the operation of changing the first setting values  56 . In this case, in the state in which the first setting values  56  are set, the projector  1  updates the first setting values  56  based on the operation performed on the operation section  31  or the remote control  7 . The user can therefore readily change the first setting values  56 . 
     The projection system  100  includes the projection  1  including the projection apparatus  10 , which projects a projection image, and the controller  50 , and the base apparatus  2 , which specifies the direction in which the projector  1  projects the image light PL and the position where the projector  1  is installed when the projector  1  is attached to the base apparatus  2 . The controller  50  causes the projection apparatus  10  to project a projection image based on the first setting values  56  with the projector  1  attached to the base apparatus  2 . The controller  50  changes the settings of the projector  1  from the first setting values  56  to the to the second setting values  57  when the projector  1  is detached from the base apparatus  2 . The controller  50  changes the settings of the projector  1  from the second setting values  57  to the to the first setting values  56  when the controller  50  detects that the projector  1  has been attached to the base apparatus  2 . The set of first setting values  56  and the set of second setting values  57  each include a parameter relating to the geometric correction of the projected image. 
     According to the thus configured projection system  100 , when the projector  1  is attached to the base apparatus  2 , the settings of the projector  1  are made based on the first setting values  56  including the parameter relating to the geometric correction in correspondence with the direction in which the projector  1  projects the image light PL and the position where the projector  1  is installed. When the projector  1  is detached from the base apparatus  2 , the settings of the projector  1  are made based on the second setting values  57 . The frequency of the operation of changing the settings of the projection apparatus  10  including the geometric correction parameter in accordance with the location where the projector  1  is used can thus be reduced. The settings of the projector  1 , which can be detached from the base apparatus  2  and carried around, can therefore be readily changed in accordance with the location where the projector  1  is installed. 
     2. Second Embodiment 
       FIG.  7    is a sequence diagram showing the action of the projection system  100  according to a second embodiment. In the second embodiment, the configuration of the projection system  100  is the same as that in the first embodiment, and no illustration or description of the configuration of the projection system  100  will be made. 
     In the second embodiment, the memory  213  stores the first setting values  56 . The base apparatus  2  is fixed or installed at the location where the projector  1  is used so as to specify the projection direction LD and the installation position of the projector  1 , as shown in  FIG.  4   . The base apparatus  2  stores in the memory  213  appropriate first setting values  56  corresponding, for example, to the relative positional relationship between the location where the base apparatus  2  is installed and the screen SC. For example, the first setting values  56  stored by the base apparatus  2 A include setting values suitable for the case where the projector  1  is operated at the location where the base apparatus  2 A is installed. The first setting values  56  stored by the base apparatus  2 B include setting values suitable for the case where the projector  1  is operated at the location where the base apparatus  2 B is installed. In this case, the first setting values  56  stored by the base apparatus  2  may not include the base ID  560 . The memory  213  corresponds to an example of a second storage section. 
     The action shown in  FIG.  7    is the action performed when the projector  1  is not attached to the base apparatus  2  and the projector  1  is then attached to the base apparatus  2  and performed in place of the action in  FIG.  5    in the first embodiment. In  FIG.  7   , the controller  50  carries out the processes in steps SA 15  to SA 18 , SA 20 , SA 21 , SA 51 , SA 52 , and SA 53 , and the transmission control section  210  carries out the processes in steps SB 11 , SB 13 , SB 51 , and SB 52 . In  FIG.  7   , processes common to those in  FIG.  5    have the same step numbers and will not be described. 
     The base apparatus  2  detects in step SB 11  that the projector  1  has been coupled to the base apparatus  2  and then transitions to step SB 51 . In step SB 51 , the base apparatus  2  transmits a control signal containing the first setting values  56  to the projector  1 . 
     The projector  1  receives the control signal transmitted by the base apparatus  2  an step SA 51  to sense that the projector  1  has been coupled to the base apparatus  2 . The projector  1  transitions to step SA 52 , where the projector  1  acquires the first setting values  56  contained in the control signal transmitted by the base apparatus  2  and changes the settings of the portions of the projector  1  including the projection apparatus  10  based on the acquired first setting values  56 . The projector  1  then transitions to step SA 15 . 
     In step SA 18 , the projector  1  evaluates whether or not the operation of instructing a change in the settings relating to the action of the projector  1  has been performed, for example, via the operation section  31  or the remote control  7 . When the operation of instructing a change in the settings is performed (YES in step SA 18 ), the projector  1  transitions to step SA 53  to instruct the base apparatus  2  to update the first setting values  56 . 
     The base apparatus  2  updates in step SB 52  the first setting values  56  stored by the memory  213  in accordance with the instruction transmitted by the projector  1 . 
     The projection system  100  described in the second embodiment can provide the same effects as those provided by the first embodiment. 
     The method for controlling the projector  1  described in the second embodiment further includes transmitting the first setting values  56  stored in the memory  213  provided in the base apparatus  2  to the projector  1  from the base apparatus  2  when the projector  1  detects that the projector  1  has been attached to the base apparatus  2 . Thereafter, when the projector  1  accepts the operation of changing the settings thereof to the first setting values  56 , the projector  1  updates the first setting values  56  stored by the memory  213 . 
     The settings including the optical system of the projector  1  can thus be appropriately set in accordance with the environment in which the projector  1  is used. The configuration in which the base apparatus  2  stores as the first setting values  56  the setting values of the projector  1  in the environment in which the base apparatus  2  to which the projector  1  can be attached is installed allows the projector  1  to be appropriately set in accordance with the environment in which the projector  1  is used even when the projector  1  does not store the first setting values  56  in advance. The projector  1  can therefore be appropriately and readily set even when the projector  1  is used in an unknown environment. 
     3. Third Embodiment 
       FIG.  8    is a sequence diagram showing the action of the projection system  100  according to a third embodiment. In the third embodiment, the configuration of the projection system  100  is the same as that in the first embodiment, and no illustration or description of the configuration of the projection system  100  will be made. 
     In the third embodiment, the projector  1  detects that the projector  1  has been attached to the base apparatus  2  and notifies the base apparatus  2  of the attachment. In the configuration described above, the base apparatus  2  does not need to sense that the projector  1  has been attached to the base apparatus  2  with the aid, for example, of the switch  25 . 
     The action shown in  FIG.  8    is the action performed when the projector  1  is not attached to the base apparatus  2  and the projector  1  is then attached to the base apparatus  2  and performed in place of the action in  FIG.  5    in the first embodiment. In  FIG.  8   , the controller  50  carries out the processes in steps SA 13  to SA 21  and SA 61  to SA 63 , and the transmission control section  210  carries out the processes in steps SB 13 , SB 61 , and SB 62 . In  FIG.  8   , processes common to those in  FIG.  5    have the same step numbers and will not be described. 
     In step SA 61 , the projector  1  detects that the projector  1  has been coupled to the base apparatus  2 . In step SA 61 , the method for detecting that the projector  1  has been coupled to the base apparatus  2  can be any of the methods in Specific Examples 1 to 4 described above. 
     The projector  1  transitions to the step SA 62 , where the projector  1  inquires of the base apparatus  2  the base ID. 
     The base apparatus  2  accepts in step SB 61  the inquiry made by the projector  1 . The base apparatus  2  transitions to step SB 62 , where the base apparatus  2  transmits a control signal containing the base ID  216  stored by the memory  213  to the projector  1 . 
     In step SA 63 , the projector  1  receives the control signal transmitted by the base apparatus  2  and acquires the base ID contained in the received control signal. The following actions of the projector  1  and the base apparatus  2  are the same as those in step SA 13  and the following steps described in the first embodiment. 
     The projection system  100  described in the third embodiment can provide the same effects as those provided by the first embodiment. 
     The method for controlling the projector  1  described in the third embodiment further includes causing the projector  1  to sense that the projector  1  has been attached to the base apparatus  2  and causing the projector  1  to inquire of the base apparatus  2  the base ID. The base apparatus  2  therefore does not need to sense that the projector  1  has been attached to the base apparatus  2 . The configuration of the base apparatus  2  can thus be simplified. 
     4. Other Embodiments 
     The embodiments described above are preferable embodiments of the present disclosure. The present disclosure is, however, not limited to the embodiments described above, and a variety of variations are conceivable to the extent that the variations do not depart from the substance of the present disclosure. 
     In the first and third embodiments described above, the projector may store first setting values  56  independent of a specific base apparatus  2 . That is, the projector  1  may store general-purpose first setting values  56  that are not associated with a specific base ID  560 . For example, the projector  1  acquires the general-purpose first setting values  56  when no base ID is transmitted from the base apparatus  2  or when no first setting values  56  associated with the base ID transmitted from the base apparatus  2  are stored in the memory  53 . The projector  1  can thus project an image even when the projector  1  is attached to the base apparatus  2  but cannot acquire an effective base ID from the base apparatus  2 . In this case, in response to the setting value changing instruction issued from the operation section  31  or the remote control  7 , the projector  1  may generate new first setting values  56  including a new base ID and store the generated first setting values  56  in the memory  53 . 
     For example, a relay apparatus that amplifies or distributes an image signal may be interposed between the projector  1  and the base apparatus  2 . In this case, the projector  1  and the base apparatus  2  are electrically coupled to each other via the relay apparatus. Specifically, the projector  1  is electrically coupled to the relay apparatus via a cable and terminals, and the base apparatus  2  is electrically coupled to the relay apparatus via a cable and terminals. In this case, the coupling between the projector  1  and the base apparatus  2  via the relay apparatus is sensed by at least one of the projector  1  and the base apparatus  2 , so that any of the actions shown in the embodiments described above can be applied. 
     The embodiments described above have been described with reference to the case where the projector  1  projects the image light PL forward, but the aspect of the projection performed by the projector  1  not limited to a specific aspect. For example, the projector  1  may be a rear-projection projector  1 . Furthermore, the image light PL may be projected onto a horizontal surface, such as the upper surface of the desk  411  or a three-dimensional object, such as a wall surface of a building. 
     The configurations of the projector  1  and the base apparatus  2  shown in  FIG.  2    each represent a functional configuration and are each not necessarily implemented in a specific form. That is, hardware corresponding to each of the functional portions is not necessarily implemented, and a single processor that executes a program can, of course, achieve the functions of the plurality of functional portions. Furthermore, in the embodiments and variations described above, part of the functions achieved by software may be achieved by hardware, or part of the functions achieved by hardware may be achieved by software. 
     The process units in the sequence diagrams shown in  FIGS.  5 ,  7 , and  8    are process units divided in accordance with the contents of primary processes for easy understanding of the processes carried out by the processors  51  and  211 . How to produce the divided process units or the names of the process units do not limit the present disclosure. The processes carried out by the processors  51  and  211  can each be further divided into a larger number of process units, or can each be so divided that one process unit includes a larger number of processes in accordance with the content of the process. Furthermore, the order in which the processes are carried out in the flowchart of  FIG.  6    is not limited to that shown in  FIG.  6   . 
     The control program  55  executed by the processor  51  can instead be recorded, for example, on a recording medium readable by the projector  1 . The recording medium can be a magnetic or optical recording medium or a semiconductor memory device. Specific examples of the recording medium may include a flexible disk, a CD-ROM (compact disk read only memory), a DVD, a Blu-ray Disc, a magneto-optical disk, a flash memory, and a portable or immobile recording medium, such as a card-shaped recording medium. The programs can be stored, for example, in a server apparatus, and the projector  1  can download the programs from the server apparatus to achieve the display control method described above. The same holds true for the control program  215  executed by the processor  211 . Blu-ray is a registered trademark.