PROJECTOR AND CONTROL METHOD
Technical Field
[0001] The present invention relates to a projector and a control method.
Background Art
[0002] There is a known interactive system including a projector that projects an image and
a light emitting pen that is operated by a user on the projected image (see PTL 1, for
example). The light emitting pen emits infrared light through the nib thereof, and the
projector detects the infrared light emitted from the light emitting pen and recognizes
what user's operation is. In a proposed interactive system of this type, the projector also
includes a light emitting device that emits infrared light for synchronized commu
nication between the projector and the light emitting pen. In this system, the light
emitting pens emits light in response to the infrared light emitted from the projector.
Citation List
Patent Literature
[0003] PTL 1: JP-A-2012- 173447
Summary of Invention
Technical Problem
[0004] When the interactive system described above is disposed at a plurality of locations
close to each other, one of the light emitting pens undesirably receives infrared light
fluxes transmitted from a plurality of the projectors in some cases. In such cases, the
light emitting pen attempts to respond to the infrared light fluxes, undesirably resulting
in unsuccessful synchronization between the light emitting pen and the corresponding
projector. To address the problem, configuring each of the projectors in such a way
that the projector, when it receives infrared light from any of the other projectors, emits
infrared light at the same timing in response thereto prevents the light emitting pen a s
sociated with the projector from receiving infrared light fluxes from a plurality of the
projectors at different timings. The projectors thus correctly operate. One of the
projectors, however, cannot always receive infrared light from any of the other
projectors in a stable manner depending on the distance between the two projectors and
the arrangement thereof, which means that the projector may undesirably emit infrared
light at an unstable timing.
Solution to Problem
[0005] An advantage of some aspects of the invention is to provide a projector and a control
method that allow a plurality of projectors to be used and to operate in a stable manner.
[0006] (1) An aspect of the invention is directed to a projector including a plurality of
transmitters each of which transmits a signal, a receiver that receives signals
transmitted from another projector, and a control unit that achieves synchronization of
the signals between the projector and the another projector based on the signals
transmitted from the another projector and received by the receiver, and the control
unit includes a state judgment portion that judges whether or not the synchronization
with the another projector is stable and a number determination portion that determines
the number of transmitters to be used among the plurality of transmitters based on the
judgment result made by the state judgment portion.
[0007] The thus configured projector monitors the signals received from the another
projector and determines the number of transmitters to be used among the plurality of
transmitters in accordance with the synchronization state representing whether or not
the synchronization between the projector and the another projector is stable based on
the signals received from the another projector to achieve stable synchronization with
the another projector or suppress interference from the another projector, whereby a
plurality of projectors can be used and allowed to operate in a stable manner.
[0008] (2) Another aspect of the invention is directed to the projector described above,
wherein the control unit further includes a synchronization judgment portion that
judges whether or not the projector is synchronized with the another projector and a
timing determination portion that determines a timing at which each of the transmitters
transmits the signal based on the judgment result made by the synchronization
judgment portion.
[0009] The thus configured projector can control the synchronization among a plurality of
projectors by judging whether or not the projectors are synchronized with each other
and changing the timing at which each of the transmitters transmits the signal based on
the judgment having been made.
[0010] (3) Still another aspect of the invention is directed to the projector described above,
wherein the control unit further includes a mode determination portion that determines
a mode of the projector to be one of the following modes based on the judgment result
made by the state judgment portion: a primary mode in which the another projector is
synchronized with the projector; and a secondary mode in which the projector is syn
chronized with the another projector.
[001 1] The thus configured projector can track the state of synchronization among a
plurality of projectors by judging the state of synchronization and allowing the mode
determination portion to determine the mode of the projector to be the primary mode or
the secondary mode in accordance with the judged state of synchronization.
[0012] (4) Yet another aspect of the invention is directed to the projector described above,
wherein when the synchronization between the projector and the another projector is
not stable, the state judgment portion judges that the projector is in an unstable state,
and when the state judgment portion judges that the projector is in the unstable state,
the number determination portion determines to increase or decrease the number of
transmitters to be used among the plurality of transmitters.
[0013] The thus configured projector can change the magnitude of the transmitted signals by
judging the state of synchronization and increasing or decreasing the number of
transmitters that transmit the signals to the another projector based on the judged state
of synchronization, whereby the synchronization between the projector and the another
projector can be controlled.
[0014] (5) Still yet another aspect of the invention is directed to a method for controlling a
projector including a first process of causing a plurality of transmitters to each transmit
a signal, a second process of receiving signals transmitted from another projector, a
third process of achieving synchronization of the signals between the projector and the
another projector based on the signals received from the another projector in the
second process, a fourth process of judging whether or not the synchronization with the
another projector is stable, and a fifth process of determining the number of
transmitters to be used among the plurality of transmitters based on the judgment result
made in the fourth process.
[0015] In the thus configured control method, the projector monitors the signals received
from the another projector and determines the number of transmitters to be used among
the plurality of transmitters in accordance with the synchronization state representing
whether or not the synchronization between the projector and the another projector is
stable based on the signals received from the another projector to achieve stable syn
chronization with the another projector or suppress interference from the another
projector, whereby a plurality of projectors can be used and allowed to operate in a
stable manner.
[0016] According to the aspects of the invention, a plurality of projectors can be used and
allowed to operate in a stable manner.
Brief Description of Drawings
[0017] [fig.l]Fig. 1 is a schematic view for describing a situation in which interactive systems
according to an embodiment of the invention are used.
[fig.2]Fig. 2 is a schematic block diagram showing an example of the configuration of
a projector according to the present embodiment.
[fig.3]Fig. 3 is a flowchart showing an example of detailed synchronization control
performed by a control unit according to the present embodiment.
Description of Embodiment
[0018] Embodiment
An embodiment of the invention will be described below in detail with reference to
the drawings.
[0019] Fig. 1 is a schematic view for describing a situation in which interactive systems SI
and S2 according to the embodiment of the invention are used.
The interactive system SI includes a projector 1-1 and a light emitting pen 2-1.
[0020] The projector 1-1 projects an image Gl on a projection surface SC. A user can point
part of the image Gl projected on the projection surface SC (hereinafter referred to as
projected image) and draw a figure, a character, and other objects on the image Gl by
using the light emitting pen 2-1. At this point, the projector 1-1 and the light emitting
pen 2-1 are synchronized with each other based on infrared light communication. That
is, the projector 1-1 emits (transmits) infrared light PT1 in a predetermined light
emission pattern, and the light emitting pen 2-1 receives the infrared light PT1 from
the projector 1-1 and then emits (transmits) infrared light PR1 in response to the
reception of the infrared light PT1. The projector 1-1 then receives the infrared light
PR1 and recognizes, for example, the position where the light emitting pen 2-1 has
emitted light.
[0021] The projector 1-1 thus produces an image according to user's operation of the light
emitting pen 2-1, which is called an operation image, and projects a new projected
image Gl, which is the previous projected image Gl on which the produced operation
image is superimposed, on the projection surface SC.
[0022] The interactive system S2 includes a projector 1-2 and a light emitting pen 2-2.
[0023] The projector 1-2 projects an image G2 on the projection surface SC. A user can
point part of the image G2 projected on the projection surface SC and draw a figure, a
character, and other objects on the image G2 by using the light emitting pen 2-2. At
this point, the projector 1-2 and the light emitting pen 2-2 are synchronized with each
other based on infrared light communication. That is, the projector 1-2 emits infrared
light PT2 in a predetermined light emission pattern, and the light emitting pen 2-2
receives the infrared light PT2 from the projector 1-2 and then emits infrared light PR2
in response to the reception of the infrared light PT2. The projector 1-2 then receives
the infrared light PR2 and recognizes, for example, the light emission position.
[0024] The projector 1-2 thus produces an image according to user's operation of the light
emitting pen 2-2, which is called an operation image, and projects a new projected
image G2, which is the previous projected image G2 on which the produced operation
image is superimposed, on the projection surface SC.
[0025] When the interactive systems SI and S2 are installed at locations relatively close to
each other, the infrared light PT1 emitted from the projector 1-1, for example, may be
undesirably received by the light emitting pen 2-2 in some cases. In such cases, the
light emitting pen 2-2 attempts to emit light in response to both the infrared light PT1
from the projector 1-1 and the infrared light PT2 from the projector 1-2, resulting in
unsuccessful synchronization between the projector 1-2 and the light emitting pen 2-2.
[0026] To address the problem, synchronizing the projectors 1-1 and 1-2 with each other to
cause them to emit the infrared light PT1 and the infrared light PT2 at the same timing
prevents the light emitting pen 2-2 that receives both the infrared light PT1 and the
infrared light PT2 from responding to both the projectors 1-1 and 1-2 but allows the
light emitting pen 2-2 to be successfully synchronized with the projector 1-2.
[0027] It is assumed in the present embodiment that the infrared light PT1 for synchronizing
the projector 1-1 with the light emitting pen 2-1 and the infrared light PT2 for syn
chronizing the projector 1-2 with the light emitting pen 2-2 are used as they are to syn
chronize the projectors 1-1 and 1-2 with each other. That is, the infrared light PT1 and
the infrared light PT2 are sync signals not only for synchronizing the projector 1-1
with the light emitting pen 2-1 and the projector 1-2 with the light emitting pen 2-2 re
spectively but also for synchronizing the projectors 1-1 and 1-2 with each other.
[0028] In the following description, the projectors 1-1 and 1-2 are collectively called a
projector 1 unless otherwise stated because the configuration of the projector 1-1 is the
same as the configuration of the projector 1-2. Similarly, the light emitting pens 2-1
and 2-2 are collectively called a light emitting pen 2.
[0029] Fig. 2 is a schematic block diagram showing an example of the configuration of the
projector 1 according to the present embodiment.
[0030] The projector 1 includes a light reception unit 11, a control unit 12, and a light
emission unit 13. The light reception unit 11 includes an imager 111 and a receiver
112. The control unit 12 includes a detection section 121, a judgment section 122, a de
termination section 123, and a light emission controller 124. The judgment section 122
includes a synchronization judgment portion 1221 and a state judgment portion 1222.
The determination section 123 includes a mode determination portion 1231, a timing
determination portion 1232, and a number determination portion 1233. The projector 1
has other functions of a typical projector (image projection function, for example), but
the other functions will not be illustrated or described.
[0031] The imager 111 focuses light (infrared light, for example) emitted from an imaging
target object on an imaging device. Specifically, the imager 111 includes a CCD
(charge coupled device) sensor, a CMOS (complementary metal oxide semiconductor)
sensor, or any other imaging device (not shown) and an imaging lens (not shown). The
imager 111 is, for example, disposed in the vicinity of a projection lens (not shown) of
the projector 1 and captures images of a projected-image-containing area of the
projection surface SC at a predetermined frame rate. The imager 111 produces image
information representing images captured with the imaging device (hereinafter referred
to as captured images) and outputs the produced image information to the detection
section 121.
[0032] The receiver 112 receives the infrared light emitted from the light emitting pen 2, the
other projector 1, or any other object and outputs a reception result (received in
formation) to the detection section 121.
[0033] The detection section 121 includes a CPU (central processing unit), a RAM (random
access memory) used, for example, to temporarily store a variety of data, a mask ROM
(read only memory), a flash memory, an FeRAM (ferroelectric random access
memory), or any other nonvolatile memory, and an image analysis processor (none of
the above components is shown). The detection section 121, in which the CPU
operates in accordance with a control program stored in the nonvolatile memory,
controls the action of the light reception unit 11.
[0034] The detection section 121 analyzes the image information inputted from the imager
111 to detect the coordinates of the position on the captured image where the light
emitting pen 2 has emitted light. The detection section 121 converts the detected co
ordinates of the position of the light emitting pen 2 on the captured image into the co
ordinates of the on-image position in the input image signal to produce information on
the position of the light emitting pen 2. In the control unit 12, an image processor (not
shown) reflects the positional information produced by the detection section 121 in the
projected image by superimposing a predetermined mark or any other object in a
position based on the positional information.
[0035] The detection section 121 further analyzes the received information inputted from the
receiver 112 to detect the infrared light emitted from the other projector 1. When the
infrared light emitted from the other projector 1 is detected, the detection section 121
outputs detection timing information representing the timing at which the infrared light
has been emitted to the judgment section 122 and the determination section 123. When
no infrared light emitted from the other projector 1 is detected, the detection section
121 outputs non-detection information representing that no infrared light has been
detected to the determination section 123.
[0036] The synchronization judgment portion 1221 judges whether or not the projectors 1
are synchronized with each other (whether or not projector 1-1 and projector 1-2 are
synchronized with each other, for example) based on the detection timing information
inputted from the detection section 121 and setting timing information set in the light
emission controller 124, which will be described later, (information on timing at which
light emission unit 13 actually emits light). Specifically, the synchronization judgment
portion 1221 compares the timing represented by the detection timing information with
the timing represented by the setting timing information. When the two timings
coincide with each other, the synchronization judgment portion 1221 judges that the
projector in which the synchronization judgment portion 1221 is included (projector 1,
hereinafter sometimes referred to as own projector) is synchronized with the other
projector 1. On the other hand, when the timing represented by the detection timing in
formation differs from the timing represented by the setting timing information, the
synchronization judgment portion 1221 judges that the own projector is not syn
chronized with the other projector 1. The synchronization judgment portion 1221
outputs the judgment result to the state judgment portion 1222.
[0037] The state judgment portion 1222 judges the state of synchronization between the own
projector and the other projector 1 based on the judgment result inputted from the syn
chronization judgment portion 1221. Specifically, when a judgment result representing
that the synchronization is achieved is not inputted from the synchronization judgment
portion 1221 within a predetermined period, the state judgment portion 1222 judges
that the own projector and the other projector 1 are not synchronized with each other or
are in an asynchronous state. On the other hand, when the judgment result representing
that the synchronization is achieved is inputted from the synchronization judgment
portion 1221 within the predetermined period at a frequency higher than or equal to a
predetermined value, the state judgment portion 1222 judges that the own projector
and the other projector 1 are synchronized with each other in a stable manner or are in
a stable state. Further, when the judgment result representing that the synchronization
is achieved is inputted from the synchronization judgment portion 1221 within the pre
determined period at a frequency lower than the predetermined value, the state
judgment portion 1222 judges that the own projector and the other projector 1 are syn
chronized with each other in an unstable manner or are in an unstable state. The state
judgment portion 1222 outputs state information representing the judgment result to
the determination section 123.
[0038] The mode determination portion 1231 determines an action mode of the projector 1
based on the non-detection information inputted from the detection section 121, the
state information inputted from the state judgment portion 1222, and other types of in
formation. Specifically, the mode determination portion 1231 determines the action
mode to be a primary mode in which the other projector 1 is synchronized with the
own projector (hereinafter sometimes referred to as master) or a secondary mode in
which the own projector is synchronized with the other projector (hereinafter
sometimes referred to as slave). For example, the mode determination portion 1231 de
termines the action mode to be the primary mode when the non-detection information
is inputted from the detection section 121, whereas determining the action mode to be
the secondary mode when state information representing the asynchronous state is
inputted from the state judgment portion 1222. The mode determination portion 1231
outputs mode information representing the determined mode to the timing deter
mination portion 1232.
[0039] The timing determination portion 1232 determines the timing at which the limit
emission unit 13 emits light based on the detection timing information inputted from
the detection section 121 and the mode information inputted from the mode deter
mination portion 1231. Specifically, when the mode information shows the secondary
mode, the timing determination portion 1232 outputs the inputted detection timing in
formation as the setting timing information to the light emission controller 124 so that
the light emission unit 13 emits light at the timing represented by the detection timing
information.
[0040] The number determination portion 1233 determines the number of light emitting
devices driven to emit light among a plurality of light emitting devices provided in the
light emission unit 13 based, for example, on the state information inputted from the
state judgment portion 1222 and outputs the determined number as number in
formation to the light emission controller 124.
[0041] The light emission controller 124 controls the light emission of the light emission
unit 13 based on the setting timing information inputted from the timing determination
portion 1232 and the number information inputted from the number determination
portion 1233. Specifically, the light emission controller 124 causes the light emitting
devices the number of which is represented by the number information to emit light at
the timing represented by the setting timing information.
[0042] The light emission unit 13 includes a plurality of light emitting devices, for example,
infrared LEDs, which are caused to emit light under the control of the light emission
controller 124.
[0043] Fig. 3 is a flowchart showing an example of detailed synchronization control
performed by the control unit 12 according to the present embodiment.
[0044] In step ST201, having acquired an operation signal representing that the user has
switched the state of a power switch from an off state to an on state, the control unit 12
performs synchronization control including processes in step ST202 and the following
steps.
[0045] In step ST202, the detection section 121 attempts to detect the infrared light emitted
from the other projector 1. When the infrared light is detected (Yes), the detection
section 121 outputs the detection timing information representing the timing at which
the detected infrared light has been emitted to the judgment section 122 and the deter
mination section 123, and the control proceeds to step ST208. On the other hand, when
the infrared light emitted from the other projector 1 is not detected (No), the detection
section 121 outputs the non-detection information to the determination section 123,
and the control proceeds to step ST203.
[0046] In step S203, when the non-detection information is inputted from the detection
section 121, the mode determination portion 1231 sets the action mode to be the
master, and the control proceeds to step ST204.
[0047] In step ST204, the detection section 121 attempts to detect the infrared light emitted
from the other projector 1 again. When the infrared light is detected (Yes), the
detection section 121 outputs the detection timing information to the judgment section
122 and the determination section 123, and the control proceeds to step ST205. On the
other hand, when the infrared light emitted from the other projector 1 is not detected
(No), the detection section 121 outputs the non-detection information to the deter
mination section 123 and repeats step ST204.
[0048] In step ST205, the synchronization judgment portion 1221 judges whether or not the
detected other projector 1 is synchronized with the own projector. Further, the state
judgment portion 1222 judges the state of synchronization between the own projector
and the other projector 1 based on the judgment result from the synchronization
judgment portion 1221. When the synchronization judgment portion 1221 judges that
the own projector is synchronized with the other projector 1 (Yes), the control
proceeds to step ST206. On the other hand, when the synchronization judgment portion
1221 judges that the own projector is not synchronized with the other projector 1 (No),
the control proceeds to step ST208 and the mode determination portion 1231 sets the
action mode to be the slave.
[0049] In step ST206, the state judgment portion 1222 judges whether or not the synchro
nization between the own projector and the other projector 1 is stable. When the syn
chronization is stable (Yes), the control returns to step ST204. On the other hand, when
the synchronization is not stable (No), the control proceeds to step ST207.
[0050] In step ST207, the number determination portion 1233 changes the number of light
emitting devices driven to emit light among the plurality of light emitting devices
provided in the light emission unit 13. The light emission controller 124 increases or
decreases the number of light emitting devices driven to emit light based on the
number determined by the number determination portion 1233, and the control returns
to step ST204.
[0051] In step ST208, when the detection timing information is inputted from the detection
section 121, the mode determination portion 1231 sets the action mode to be the slave.
The timing determination portion 1232 then outputs the inputted detection timing in
formation as the setting timing information to the light emission controller 124, and the
control proceeds to step ST209. As a result, the light emission unit 13 emits light at the
timing represented by the detection timing information. That is, synchronized with the
master projector 1, the light emission unit 13 emits light.
[0052] In step ST209, the detection section 121 attempts to detect the infrared light emitted
from the other projector 1 again. When the infrared light is detected (Yes), the
detection section 121 outputs the detection timing information to the judgment section
122 and the determination section 123, and the control proceeds to step ST210. On the
other hand, when the infrared light emitted from the other projector 1 is not detected
(No), the detection section 121 outputs the non-detection information to the deter
mination section 123, and the control proceeds to step ST203, where the mode deter
mination portion 1231 set the action mode to be the master.
[0053] In step ST210, the synchronization judgment portion 1221 judges whether or not the
own projector is synchronized with the detected other projector 1. Further, the state
judgment portion 1222 judges the state of synchronization between the own projector
and the other projector based on the judgment result from the synchronization
judgment portion 1221. When the synchronization judgment portion 1221 judges that
the own projector is synchronized with the other projector 1 (Yes), the control
proceeds to step ST21 1. On the other hand, when the synchronization judgment portion
1221 judges that the own projector is not synchronized with the other projector 1 (No),
the control returns to step ST208.
[0054] In step ST21 1, the state judgment portion 1222 judges whether or not the synchro
nization between the own projector and the other projector 1 is stable. When the syn
chronization is stable (Yes), the control returns to step ST209. On the other hand, when
the synchronization is not stable (No), the control proceeds to step ST212.
[0055] In step ST212, the number determination portion 1233 changes the number of light
emitting devices driven to emit light among the plurality of light emitting devices
provided in the light emission unit 13. The light emission controller 124 increases or
decreases the number of light emitting devices driven to emit light based on the
number determined by the number determination portion 1233, and the control returns
to step ST209.
[0056] When a plurality of projectors 1, each of which operates as described above, are in
operation, a projector 1 that has started operating early is set to be the master, and a
projector 1 that has started operating later is set to be the slave when the master
projector 1 is detected. In the projector 1 having been set to be the slave, the light
emission unit 13 emits light in synchronization with the projector 1 having been set to
be the master. The master projector 1 may be switched to the slave projector 1 and vice
versa in accordance with the state of synchronization between the two projectors 1, or
the two projectors 1 may both operate as the master. When the synchronization is
unstable, the number of light emitting devices is changed.
[0057] In steps ST207 and ST212, the number of light emitting devices driven to emit light
may be either increased or decreased. For example, in a state in which the synchro
nization between two projectors 1 is unstable, increasing the number of light emitting
devices driven to emit light in both the projectors 1 tends to achieve stable synchro
nization because the infrared light from each of the projectors 1 tends to reach the
other. On the other hand, decreasing the number of light emitting devices driven to
emit light in both the projectors 1 tends to cause transition from the unstable synchro
nization state to the asynchronous state because the infrared light from each of the
projectors 1 does not tend to reach the other. As a result, a situation in which the
infrared light emitted from each of the projectors 1 interferes with the infrared light in
the other interactive system will not occur, resulting in stable operation in each of the
interactive systems. In this case, both the projectors 1 operate as the master. Further,
when the number of light emitting devices driven to emit light is increased in one of
the projectors 1 and the number of light emitting devices driven to emit light is
decreased in the other projector 1, the projector 1 in which a larger number of light
emitting devices emit light is set to be the master and the projector 1 in which a smaller
number of light emitting devices emit light is set to be the slave. In this case as well,
the synchronization between the two projectors tends to be stable because the infrared
light from the master projector 1 tends to reach the slave projector 1.
[0058] The present embodiment has been described with reference to two interactive
systems, but the invention is similarly applicable to a case where three or more in
teractive systems are disposed in positions close to each other. Further, the description
has been made of the case where the light emission unit 13 in the projector 1 emits
infrared light and the light emitting pen 2 also emits infrared light, but they may, for
example, emit visible light. Moreover, the light emitted from the light emission unit 13
in the projector 1 and the light emitted from the light emitting pen 2 may differ from
each other in terms of wavelength.
[0059] As described above, according to the present embodiment, the projector 1 includes a
plurality of transmitters each of which transmits a signal (plurality of light emitting
devices in light emission unit 13), a receiver (light reception unit 11) that receives
signals transmitted from the other projector 1, the control unit 12, which achieves
signal synchronization between the own projector and the other projector 1 based on
the signals transmitted from the other projector 1 and received by the receiver (light
reception unit 11), the state judgment portion 1222, which judges whether or not the
synchronization with the other projector is stable, and the number determination
portion 1233, which determines the number of transmitters (light emitting devices in
light emission unit 13) to be used among the plurality of transmitters (light emitting
devices in light emission unit 13) based on the judgment result made by the state
judgment portion 1222.
[0060] The thus configured projector 1 monitors the signals received from the other
projector 1 and determines the number of transmitters (number of light emitting
devices in light emission unit 13) to be used among the plurality of transmitters (light
emitting devices in light emission unit 13) in accordance with the synchronization state
representing whether or not the synchronization between the own projector and the
other projector 1 is stable based on the signals received from the other projector to
achieve stable synchronization with the other projector 1 or suppress interference from
the other projector, whereby a plurality of projectors can be used and allowed to
operate in a stable manner.
[0061] Part or the entire of the projector 1 in the embodiment described above may be
achieved by a computer. In this case, a program for achieving the control function of
the projector may be stored on a computer readable storage medium, and the program
stored on the storage medium may be read into a computer system and executed to
achieve the control function.
[0062] The "computer system" used herein is assumed to be a computer system built in the
projector 1 and including an OS and a peripheral apparatus or any other type of
hardware. Further, the "computer readable storage medium" used herein refers to a
flexible disk, an magneto-optical disk, a ROM, a CD-ROM, and other portable media
and a hard disk drive and other storage devices built in the computer system.
Moreover, the "computer readable storage medium" also may include a medium that
dynamically holds a program for a short period, such as a communication line in a case
where the program is transmitted via the Internet or any other network or a telephone
network line or any other communication network line and a medium that holds a
program for a fixed period, such as a volatile memory in a computer system that serves
as a server or a client in the above situation. Further, the program described above may
be a program that achieves part of the function described above. Moreover, the
function described above may be achieved by any of the programs described above
combined with a program having already been stored in the computer system.
[0063] Further, part or the entire of the projector 1 in the embodiment described above may
be achieved in the form of an integrated circuit based, for example, on LSI (large scale
integration). Each of the functional blocks of the projector 1 may be individually im
plemented in the form of a processor or part or the entire of the functional blocks may
be integrated in the form of a processor. A method for implementing the components
in the projector in the form of an integrated circuit is not necessarily based on LSI but
may be based on a dedicated circuit or a general-purpose processor. Further, when
advances of semiconductor technologies allow advent of an integrated circuit
technology that replaces LSI, an integrated circuit based on the technology may be
used.
[0064] The embodiments of the invention has been described above in detail with reference
to the drawings. The specific configurations are not limited to those described above,
and a variety of design changes and other modifications can be made thereto to the
extent that they do not depart from the substance of the invention.
Reference Signs List
SI, S2 Interactive system
1, 1-1, 1-2 Projector
2, 2-1, 2-2, Light emitting pen
11 Light reception unit
111 Imager
112 Receiver
12 Control unit
121 Detection section
122 Judgment section
1221 Synchronization judgment portion
1222 State judgment portion
123 Determination section
1231 Mode determination portion
1232 Timing determination portion
1233 Number determination portion
124 Light emission controller
13 Light emission unit

Claims
[Claim 1] A projector comprising:
a plurality of transmitters each of which transmits a signal;
a receiver that receives signals transmitted from another projector; and
a control unit that achieves synchronization of the signals between the
projector and the another projector based on the signals transmitted
from the another projector and received by the receiver, wherein
the control unit includes
a state judgment portion that judges whether or not the synchronization
with the another projector is stable, and
a number determination portion that determines the number of
transmitters to be used among the plurality of transmitters based on the
judgment result made by the state judgment portion.
[Claim 2] The projector according to claim 1, wherein
the control unit further includes
a synchronization judgment portion that judges whether or not the
projector is synchronized with the another projector, and
a timing determination portion that determines a timing at which each
of the transmitters transmits the signal based on the judgment result
made by the synchronization judgment portion.
[Claim 3] The projector according to claim 1, wherein
the control unit further includes
a mode determination portion that determines a mode of the projector
to be one of the following modes based on the judgment result made by
the state judgment portion: a primary mode in which the another
projector is synchronized with the projector; and a secondary mode in
which the projector is synchronized with the another projector.
[Claim 4] The projector according to claim 3, wherein when the state judgment
portion judges that the synchronization between the projector and the
another projector is not stable, the number determination portion de
termines to increase or decrease the number of transmitters to be used
among the plurality of transmitters.
[Claim 5] A method for controlling a projector comprising:
a first process of causing a plurality of transmitters to each transmit a
signal;
a second process of receiving signals transmitted from another
projector;
PCT/JP2014/001288
a third process of achieving synchronization of the signals between the
projector and the another projector based on the signals received from
the another projector in the second process;
a fourth process of judging whether or not the synchronization with the
another projector is stable; and
a fifth process of determining the number of transmitters to be used
among the plurality of transmitters based on the judgment result made
in the fourth process.