Planar light source device, display device, terminal device, and method for driving planar light source device

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.

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.

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.

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.