Planar light source device, display device, terminal device, and method for driving planar light source device
A display device having an optical waveguide and a light source are provided, and also having a louver, a transparent/scattering state switching element, and a transmissive liquid crystal display panel provided in the order indicated on the side of the light-emitting surface of the optical waveguide. The transparent/scattering state switching element switches between a state for scattering the incident light and a state for transmitting the light without scattering. The light source drive circuit causes the transparent/scattering state switching element to transfer from the transparent state to the scattering state, and when the viewing angle range of the display is switched from narrow to wide, the intensity of the light source is gradually increased in conjunction with the transition state of the transparent/scattering state switching element. By this configuration, abnormal flashing during switching of the radiation angle can be prevented in a planar light source device that is capable of switching the radiation angle range.
1 . A planar light source device comprising:
a light source unit for emitting light in a plane;
a transparent/scattering state switching element capable of switching between a transparent state for transmitting the light incident from the light source unit, and a scattering state for scattering the light; and
a control unit for controlling the intensity of said light source unit and the state of said transparent/scattering state switching element; wherein
said control unit gradually increases the intensity of said light source unit in conjunction with the transition state of said transparent/scattering state switching element when said transparent/scattering state switching element is transferred from said transparent state to said scattering state.
2 . The planar light source device according to claim 1 , wherein said control unit gradually reduces the intensity of said light source unit in conjunction with the transition state of said transparent/scattering state switching element when said transparent/scattering state switching element is transferred from said scattering state to said transparent state.
3 . A planar light source device comprising:
a light source unit for emitting light in a plane;
transparent/scattering state switching element capable of switching between a transparent state for transmitting the light incident from the light source unit, and a scattering state for scattering the light; and
a control unit for controlling the intensity of said light source unit and the state of said transparent/scattering state switching element; wherein
said control unit gradually increases the intensity of said light source unit after the start of the transition in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state.
4 . The planar light source device according to claim 3 , wherein said control unit increases the intensity of said light source unit after said transition is completed in said transparent/scattering state switching element.
5 . The planar light source device according to claim 3 , wherein said control unit reduces the intensity of said light source unit before the start of the transition from said scattering state to said transparent state by said transparent/scattering state switching element.
6 . A planar light source device comprising:
a light source unit for emitting light in a plane;
a transparent/scattering state switching element capable of switching between a transparent state for transmitting the light incident from the light source unit, and a scattering state for scattering the light; and
a control unit for controlling the intensity of said transparent/scattering state switching element; wherein
said control unit reduces the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state.
7 . The planar light source device according to claim 6 , wherein said control unit turns off said light source unit during said transition period.
8 . The planar light source device according to claim 6 , wherein said control unit reduces the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said scattering state to said transparent state.
9 . The planar light source device according to claim 8 , wherein said control unit turns off said light source unit during said transition from said scattering state to said transparent state.
10 . A planar light source device comprising:
a light source unit for emitting light in a plane;
a transparent/scattering state switching element capable of switching between a transparent state for transmitting the light incident from the light-source unit, and a scattering state for scattering the light; and
a control unit for controlling the intensity of said light source unit and the state of said
said control unit adjusts the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state, so that the luminance in the direction having the highest luminance of the light emitted from said light source unit and transmitted through said transparent/scattering state switching element when said transparent/scattering state switching element is in the transparent state does not become higher than said luminance before and after said transition period.
11 . The planar light source device according to claim 10 , wherein said control unit performs adjustment of the intensity of said light source unit by gradually increasing the intensity of said light source unit in conjunction with the transition state of said transparent/scattering state switching element.
12 . The planar light source device according to claim 10 , wherein said control unit performs adjustment of the intensity of said light source unit by increasing the intensity of said light source unit after the transition from said transparent state to said scattering state has been started by said transparent/scattering state switching element.
13 . The planar light source device according to claim 10 , wherein said control unit performs adjustment of the intensity of said light source unit by reducing the intensity of said light source unit during said transition period.
14 . The planar light source device according to claim 10 , wherein said control unit adjusts the intensity of said light source unit so that said luminance during the transition period in which said transparent/scattering state switching element is transferred from said scattering state to said transparent state does not become higher than said luminance before and after the transition period.
15 . The planar light source device according to claim 1 , wherein said light source unit comprises a light-emitting diode.
16 . The planar light source device according to claim 10 , wherein said light source unit comprises a light-emitting diode.
17 . The planar light source device according to claim 1 , comprising a light-direction regulating element for regulating the light-direction of the light emitted from said light source unit and emitting the light to said transparent/scattering state switching element.
18 . The planar light source device according to claim 10 , comprising a light-direction regulating element for regulating the light-direction of the light emitted from said light source unit and emitting the light to said transparent/scattering state switching element.
19 . A display device comprising the planar light source device according to claim 1; and a transmissive display panel for associating an image with the light by transmitting the light emitted from the planar light source device.
20 . A display device comprising the planar light source device according to claim 10; and a transmissive display panel for associating an image with the light by transmitting the light emitted from the planar light source device.
21 . A display device comprising:
a light source unit for emitting light in a plane;
a transparent/scattering state switching element capable of switching between a transparent state for transmitting the light incident from the light source unit, and a scattering state for scattering the light;
a transmissive display panel for associating an image with the light by transmitting the light emitted from the transparent/scattering state switching element; and
a control unit for controlling the intensity of said light source unit, the state of said transparent/scattering state switching element, and said transmissive display panel; wherein
said control unit reduces the transmittance of said transmissive display panel during the transition period in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state.
22 . The display device according to claim 21 , wherein said transmittance is reduced by displaying black color in said transmissive display panel.
23 . The display device according to claim 21 , wherein said control unit reduces the transmittance of said transmissive display panel during the transition period in which said transparent/scattering state switching element is transferred from said scattering state to said transparent state.
24 . The display device according to claim 23 , wherein said transmittance is reduced during the transition from said scattering state to said transparent state by displaying black color in said transmissive display panel.
25 . The display device according to claim 21 , wherein said light source unit comprises a light-emitting diode.
26 . The display device according to claim 21 , comprising a light-direction regulating element for regulating the light-direction of the light emitted from said light source unit and emitting the light to said transparent/scattering state switching element.
27 . The display device according to claim 19 , wherein said transmissive display panel is a liquid crystal panel.
28 . The display device according to claim 20 , wherein said transmissive display panel is a liquid crystal panel.
29 . The display device according to claim 21 , wherein said transmissive display panel is a liquid crystal panel.
30 . The display device according to claim 27 , wherein said liquid crystal panel operates on a lateral field principle, a multi-domain vertical alignment principle, or a film-compensated TN principle.
31 . The display device according to claim 28 , wherein said liquid crystal panel operates on a lateral field principle, a multi-domain vertical alignment principle, or a film-compensated TN principle.
32 . The display device according to claim 29 , wherein said liquid crystal panel operates on a lateral field principle, a multi-domain vertical alignment principle, or a film-compensated TN principle.
33 . A terminal device comprising the display device according to claim 19 .
34 . A terminal device comprising the display device according to claim 20 .
35 . A terminal device comprising the display device according to claim 21 .
36 . The terminal device according to claim 33 , comprising a mobile telephone, a personal information terminal, a gaming device, a digital camera, a video camera, a video player, a notebook-type personal computer, a cash dispenser, or a vending machine.
37 . The terminal device according to claim 34 , comprising a mobile telephone, a personal information terminal, a gaming device, a digital camera, a video camera, a video player, a notebook-type personal computer, a cash dispenser, or a vending machine.
38 . The terminal device according to claim 35 , comprising a mobile telephone, a personal information terminal, a gaming device, a digital camera, a video camera, a video player, a notebook-type personal computer, a cash dispenser, or a vending machine.
39 . A method for driving a planar light source device by causing a light source unit to emit light in a plane, switching the state of a transparent/scattering state switching element on which the light is incident between a transparent state for transmitting said light and a scattering state for scattering the light, and causing light to be emitted from said transparent/scattering state switching element, comprising:
gradually increasing the intensity of said light source unit in conjunction with the transition from said transparent state to said scattering state in said transparent/scattering state switching element.
40 . The method for driving a planar light source device according to claim 39 , comprising gradually reducing the intensity of said light source unit in conjunction with the transition from said scattering state to said transparent state in said transparent/scattering state switching element.
41 . A method for driving a planar light source device by causing a light source unit to emit light in a plane, switching the state of a transparent/scattering state switching element on which the light is incident between a transparent state for transmitting said light and a scattering state for scattering the light, and causing light to be emitted from said transparent/scattering state switching element, comprising:
increasing the intensity of said light source unit after the transition from said transparent state to said scattering state has been started by said transparent/scattering state switching element.
42 . The method for driving a planar light source device according to claim 41 , comprising increasing the intensity of said light source unit after the transition from said transparent state to said scattering state is completed in said transparent/scattering state switching element.
43 . The method for driving a planar light source device according to claim 41 , comprising reducing the intensity of said light source unit before the start of the transition from said scattering state to said transparent state by said transparent/scattering state switching element.
44 . A method for driving a planar light source device by causing a light source unit to emit light in a plane, switching the state of a transparent/scattering state switching element on which the light is incident between a transparent state for transmitting said light and a scattering state for scattering the light, and causing light to be emitted from said transparent/scattering state switching element, comprising:
reducing the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state.
45 . The method for driving a planar light source device according to claim 44 , comprising turning off said light source unit during said transition period.
46 . The method for driving a planar light source device according to claim 44 , comprising reducing the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said scattering state to said transparent state.
47 . The method for driving a planar light source device according to claim 46 , comprising turning off said light source unit during the transition from said scattering state to said transparent state.
48 . A method for driving a planar light source device by causing a light source unit to emit light in a plane, switching the state of a transparent/scattering state switching element on which the light is incident between a transparent state for transmitting said light and a scattering state for scattering the light, and causing light to be emitted from said transparent/scattering state switching element, comprising:
adjusting the intensity of said light source unit during the transition period in which said transparent/scattering state switching element is transferred from said transparent state to said scattering state, so that the luminance in the direction having the highest luminance of the light emitted from said light source unit and transmitted through said transparent/scattering state switching element when said transparent/scattering state switching element is in the transparent state does not become higher than said luminance before and after said transition period.
49 . The method for driving a planar light source device according to claim 39 , comprising:
disposing said transparent/scattering state switching element between a pair of electrodes and providing said element with a layer that is switched between a transparent state and a scattering state according to the application of a voltage by said electrodes; and
causing said pair of electrodes to be short-circuited with each other when a voltage is not applied to the layer.
50 . The method for driving a planar light source device according to claim 41 , comprising:
disposing said transparent/scattering state switching element between a pair of electrodes and providing said element with a layer that is switched between a transparent state and a scattering state according to the application of a voltage by said electrodes; and
causing said pair of electrodes to be short-circuited with each other when a voltage is not applied to the layer.
51 . The method for driving a planar light source device according to claim 44 , comprising:
disposing said transparent/scattering state switching element between a pair of electrodes and providing said element with a layer that is switched between a transparent state and a scattering state according to the application of a voltage by said electrodes; and
causing said pair of electrodes to be short-circuited with each other when a voltage is not applied to the layer.
52 . The method for driving a planar light source device according to claim 48 , comprising:
disposing said transparent/scattering state switching element between a pair of electrodes and providing said element with a layer that is switched between a transparent state and a scattering state according to the application of a voltage by said electrodes; and
causing said pair of electrodes to be short-circuited with each other when a voltage is not applied to the layer.