Image processing apparatus having control means for adjusting the color temperature of the displayed image

• US 5,132,825 A
• Filed: 02/21/1991
• Issued: 07/21/1992
• Est. Priority Date: 10/18/1989
• Status: Expired due to Term

• Current Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Original Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Inventors: Miyadera, Shunichi
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): MAI, HUY KIM
• Application Number:
  US07/658,704
• Time in Patent Office: 516 Days
• Field of Search: 350/332, 350/345, 350/331 R, 350/334, 362/26, 362/29, 362/167, 362/226, 362/372, 340/784, 340/713, 340/719, 359/85, 359/86, 354/464, 354/483, 358/28, 358/29, 358/209
• US Class Current: 349/116
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133618 for ambient light
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: H04N 23/53 of electronic viewfinders, e.g. rotatable or detachable
• CPC Class Codes: H04N 23/63 by using electronic viewfinders

Abstract

In an image processing apparatus employing a liquid crystal display, a light source is provided. The light emitted from the light source and external light are selectively utilized as the back light of the liquid crystal display. A driving circuit receives an image signal and outputs a drive signal, in accordance with the white balance of the light source. A white balance sensor is further provided in the image processing apparatus. When the external light is used as the back light, the drive signal to be supplied to the liquid crystal display is compensated so that the hue of the displayed image becomes optimum.

Claims

1. An image processing apparatus capable of receiving an image signal and displaying an optical image comprising a liquid crystal display, a back surface of said liquid crystal display being illuminated by a back light, said apparatus further comprising:

sensor means for detecting the white balance of said back light;

drive means for outputting a drive signal to said liquid crystal display based on the received image signal; and

control means for adjusting the drive signal to be supplied to said liquid crystal display in accordance with the white balance detected by said sensor means in order to adjust the color temperature of the displayed image.

2. An image processing apparatus capable of receiving an image signal and displaying an optical image corresponding thereto, comprising:

a liquid crystal display for displaying the optical image, said liquid crystal display being illuminated when a drive signal is supplied;

a light source;

an illuminating member having at least two light receiving portions for respectively receiving external light and the light emitted by said light source, an illuminating surface of said illuminating member being arranged to face the back surface of said liquid crystal display for illuminating said liquid crystal display from behind;

a casing for accommodating said liquid crystal display, said light source, and said illuminating member therein;

select means for causing said illuminating member to selectively receive either external light or the light emitted by said light source;

detecting means for detecting which one of the lights emitted from either said light source or external light is selected by said select means;

sensor means for detecting the white balance of the external light;

drive means for outputting the drive signal to said liquid crystal display, based on the received image signal; and

control means for adjusting the drive signal to be supplied to said liquid crystal display based on the white balance detected by said sensor means when said detecting means detects that external light is used as the back light in order to adjust the color temperature of the displayed image.

3. The image processing apparatus according to claim 2, wherein said drive means outputs the drive signal in accordance with the white balance of said light source.

4. The image processing apparatus according to claim 2, wherein said control means comprises a storing means for storing compensation data with respect to the white balance of said light source, and wherein said control means compensates the drive signal with reference to the data stored in said storing means, when said detecting means detects that external light is used as the back light.

5. The displaying device according to claim 2, wherein said light receiving portions are provided on the respective peripheral surfaces of said illuminating member;

and wherein said casing includes openings at the portions corresponding to said respective light receiving portions.

6. The image processing apparatus according to claim 5, wherein the surfaces of said illuminating member other than said illuminating surface and said light receiving portions are covered with at least an inner surface of said casing, and wherein said surface of said casing, which covers said illuminating member is adapted to reflect light so that the light directed towards any direction is directed towards said illuminating surface.

7. The image processing apparatus according to claim 6, wherein said light receiving portions are provided on respective opposite peripheral surfaces of said illuminating member, and wherein said casing includes two openings corresponding to said respective light receiving portions on the opposite surfaces thereof.

8. The image processing apparatus according to claim 7, wherein the surfaces of said illuminating member other than said illuminating surface and said light receiving portions are covered with at least an inner surface of said casing, and wherein the surfaces of said casing which cover said illuminating member are adapted to reflect light so that the light directed towards any direction is directed towards said illuminating surface.

9. The image processing apparatus according to claim 8, further comprising select means for causing said light receiving portions to be selectively exposed to one of the external light and the light emitted by said light source.

10. The image processing apparatus according to claim 9, wherein said select means comprises:

shutter members for respectively covering said openings formed on said casing; and

switching means for switching the opening on said casing to be covered by a respective one of said shutter members, whereby one of said openings is covered by a respective one of said shutter members while the other one of said openings is uncovered.

11. The image processing apparatus according to claim 10, wherein the surface of each of said shutter members which faces said light receiving portions is adapted to reflect light.

12. The image processing apparatus according to claim 10, wherein said switching means comprises an operating member for operating said shutter members to selectively close one of said openings.

13. The image processing apparatus according to claim 12, further comprising a light introducing member for introducing the external light to one of said light receiving portions, one end of said light introducing member being adapted to be exposed to external light, while the other end of said light introducing member being connectable to the opening corresponding to the other one of said light receiving portions.

14. The image processing apparatus according to claim 2, wherein said illuminating surface of said illuminating member is adapted to diffuse light.

15. An image processing apparatus comprising:

a liquid crystal display for displaying an optical image of an object, said liquid crystal display being capable of being illuminated by external light as a back light thereof;

optical means for forming an optical image of the object;

image receiving means for receiving and photoelectrically converting the optical image formed by said optical means;

sensor means for detecting the white balance of external light and outputting a white balance signal;

signal generating means for generating an image signal based on the photoelectrically converted optical image and the white balance signal;

drive means for outputting a drive signal to said liquid crystal display based on the image signal; and

control means for adjusting the drive signal to be supplied to said liquid crystal display based on the white balance detected by said sensor means when external light is used as the back light in order to adjust the color temperature of the displayed image.

16. The image processing apparatus according to claim 15, which further comprises:

an inner light source;

switch means for switching the light to be used as the back light between the light emitted from said inner light source and external light;

detecting means for detecting which one of the light emitted by said inner lights and external light is used as the back light.

wherein said drive means outputs the drive signal in accordance with the white balance of said inner light source, and wherein said control means adjusts the drive signal when said detecting means detects that external light is used as the back light.

17. The image processing apparatus according to claim 16, wherein said control means comprises a storing means for storing compensation data with respect to the white balance of said light source, and wherein said control means compensates the drive signal, with reference to the data stored in said storing means, when said detecting means detects that external light is used as the back light.