Light source apparatus, display apparatus, terminal apparatus, and control method thereof

• US 8,624,822 B2
• Filed: 03/02/2007
• Issued: 01/07/2014
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Inventors: Uehara, Shin-ichi, Imai, Masao
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): DAVIS, TONY O
• Application Number:
  US11/681,703
• Publication Number:
  US 20070211013A1
• Time in Patent Office: 2,503 Days
• Field of Search: 345/102, 345/204, 353/122, 348/625
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

A light source apparatus has two or more light sources that have different light-emission spectra and that can be controlled independently, and also has light sensors for detecting the quantity of light emitted by the light sources. The light sensors are composed of one type of light sensor that is not provided with a color filter for selecting the wavelength of received light, and the light sensors are sensitive to wavelength ranges that are sufficiently broad to simultaneously receive light in red, green, and blue wavelength ranges. A control circuit controls the two or more light sources to emit light in a time sequential fashion, and compares reference data with the output values of the light sensors to control the quantity of light emitted by the light sources by means of a light source drive circuit. It is thereby possible to reduce the cost and size of a light source apparatus that is capable of correcting changes in hue.

Claims

1. A light source apparatus comprising:

two or more light sources that have different light-emission spectra and that can be controlled independently;

a transparent/scattering switching element that is switchable between a state of transmitting light emitted from each of the two or more light sources and a state of scattering light emitted from each of the two or more light sources;

a light sensor that has a light-receiving wavelength range that corresponds to a light-emitting wavelength range of each of the two or more light sources and senses, in a time sequential fashion, a quantity of light emitted by each of the two or more light sources and passed through the transparent/scattering switching element; and

a controller that controls each of the two or more light sources based on sensing results outputted from the light sensor,

wherein the controller controls each of the two or more light sources to emit a predetermined quantity of light in a time sequential fashion in response to an action that a state of the transparent/scattering switching element is switched, obtains chronological sensing results outputted from the light sensor in accordance with the control in a time sequential fashion, and thereafter controls the quantity of light emitted by each of the two or more light sources based on the obtained chronological sensing results.

2. The light source apparatus according to claim 1, wherein a time period in which the control in a time sequential fashion is used to detect and control the quantity of light emitted by each of the two or more light sources is separate from a time period in which the light emitted by each of the two or more light sources is used as illumination means.

3. The light source apparatus according to claim 2, wherein a time period in which the two or more light sources simultaneously emit light is included in the time period for detecting and controlling the quantity of light emitted by each of the two or more light sources by using the control in a time sequential fashion.

4. The light source apparatus according to claim 2, wherein a time period for reducing the light quantity of each of the two or more light sources is included between the time period for detecting and controlling the quantity of light emitted by each of the two or more light sources by using the control in a time sequential fashion, and the time period in which the light emitted by each of the two or more light sources is used as illumination means.

5. The light source apparatus according to claim 2, wherein the time period for detecting and controlling the quantity of light emitted by each of the two or more light sources by using the control in a time sequential fashion is started by an external signal inputted to the controller.

6. A display apparatus comprising:

the light source apparatus according to claim 5; and

a transmissive display panel for transmitting light emitted from the light source apparatus and thereby adding an image to the light.

7. The display apparatus according to claim 6, wherein a transmittance of the transmissive display panel is reduced at least in the time period for detecting and controlling the quantity of light emitted by each of the two or more light sources by using the control in a time sequential fashion.

8. A terminal apparatus comprising the display apparatus according to claim 6, wherein:

an instruction is sent to the controller in accordance with the external signal when a display of the display apparatus is changed; and

the quantity of light emitted by each of the two or more light sources is detected and controlled by using the control in a time sequential fashion based on this instruction.

9. The light source apparatus according to claim 1, further comprising:

a unit for detecting external light,

wherein the controller uses detection results obtained by the unit for detecting external light to control the quantity of light emitted by each of the two or more light sources.

10. A display apparatus comprising:

the light source apparatus according to claim 1; and

a transmissive display panel for transmitting light emitted from the light source apparatus and thereby adding an image to the light.

11. The display apparatus according to claim 10, wherein the transmissive display panel is a display panel in field sequential mode.

12. A terminal apparatus, comprising the display apparatus according to claim 10.

13. The terminal apparatus according to claim 12, wherein the terminal apparatus is a portable phone, a personal information terminal, a game console, a digital camera, a video camera, a video player, a notebook personal computer, a cash dispenser, or a vending machine.

14. The light source apparatus according to claim 1, further comprising a light guide plate having a rectangular shape, the light guide plate receiving light on a first end surface thereof, propagating the light therethrough, and emitting the light from a main surface thereof, wherein:

the two or more light sources are located on the first end surface of the light guide plate, and

the transparent/scattering switching element is switchable between states of transmitting and scattering light that is emitted by at least one of the two or more light sources, propagated through the light guide plate, and emitted from the main surface of the light guide plate.

15. The light source apparatus according to claim 14, wherein the light sensor is located on a light emitting surface side of the transparent/scattering switching element.

16. A control method for a light source apparatus comprising two or more light sources that have different light-emission spectra and that can be controlled independently, a transparent/scattering switching element that is switchable between a state of transmitting light emitted from each of the two or more light sources and a state of scattering light emitted from each of the two or more light sources, a light detector that has a light-receiving wavelength range that corresponds to a light-emitting wavelength range of each of the two or more light sources and detects, in a time sequential fashion, a quantity of light emitted by each of the two or more light sources and passed through the transparent/scattering switching element, and a controller that controls each of the two or more light sources based on detection results outputted from the light detector,

wherein the controller controls each of the two or more light sources to emit a predetermined quantity of light in a time sequential fashion in response to an action that a state of the transparent/scattering switching element is switched, obtains chronological detection results outputted from the light detector in accordance with the control in a time sequential fashion, and thereafter controls the quantity of light emitted by each of the two or more light sources based on the obtained chronological detection results.

17. A control method for a display apparatus comprising two or more light sources that have different light-emission spectra and that can be controlled independently, a transparent/scattering switching element that is switchable between a state of transmitting light emitted from each of the two or more light sources and a state of scattering light emitted from each of the two or more light sources, alight detector that has a light-receiving wavelength range that corresponds to a light-emitting wavelength range of each of the two or more light sources and detects, in a time sequential fashion, a quantity of light emitted by each of the two or more light sources and passed through the transparent/scattering switching element, a controller that controls each of the two or more light sources based on detection results outputted from the lightdetector, and a transmissive display panel for transmitting light emitted from each of the two or more light sources and thereby adding an image to the light,

wherein the controller controls each of the two or more light sources to emit a predetermined quantity of light in a time sequential fashion in response to an action that a state of the transparent/scattering switching element is switched, obtains chronological detection results outputted from the light detector in accordance with the control in a time sequential fashion, and reduces a transmittance of the transmissive display panel in a time period of obtaining the chronological detection results outputted by the light detector in accordance with the control in a time sequential fashion.