Display control device for controlling brightness of a display installed in a vehicular cabin

• US 5,617,112 A
• Filed: 12/21/1994
• Issued: 04/01/1997
• Est. Priority Date: 12/28/1993
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yoshida, Toshio, Sisido, Michitaka
• Primary Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US08/360,958
• Time in Patent Office: 832 Days
• Field of Search: 345/63, 345/77, 345/87, 345/88, 345/102, 345/147, 345/207, 348/602, 348/673, 348/674, 348/687
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H05B 39/042 by measuring the incident light
• CPC Class Codes: H05B 41/3922 and measurement of the incident light
• CPC Class Codes: H05B 47/10 Controlling the light source

Abstract

When display control for a display device installed in a vehicular cabin is to be performed, an environmental light intensity is detected by a light sensor, and variation time function of the environmental light intensity is calculated. On the basis of the light intensity variation time function, a variation time function of a human pupil open degree is predicted. On the basis of the predicted time function, an optimal value of brightness of the display device is determined to perform display brightness control.

Claims

1. A display device, comprising:

display means for displaying a character and/or graphic pattern;

light detecting means for detecting an environmental light intensity and generating a detection signal depending upon the detected light intensity;

light intensity variation time function calculating means responsive to said detection signal for calculating a time function of variation of the light intensity;

display brightness determining means for determining a display brightness of said display means preliminary set by predicting a time function of variation of a human pupil open degree corresponding to the derived light intensity variation time function; and

display control means for performing brightness control of said display means according to the determined display brightness,

wherein said display brightness determining means includes a pupil open degree variation time function table set by preliminarily predicting time function of variation of human pupil open degree variation corresponding to said light intensity variation time function and a display brightness table preliminarily storing display brightness information indicative of optimal display brightness of said display means corresponding to said pupil open degree variation time function.

2. A display device as set forth in claim 1, wherein said pupil open degree variation time function table is a read-only memory taking said light intensity variation time function as address input and storing pupil open degree variation time functions respectively corresponding to the address inputs.

3. A display device as set forth in claim 2, wherein said display brightness table is a read-only memory taking the pupil open degree variation time function as an address input and storing said display brightness information corresponding to respective address inputs.

4. A method of controlling the brightness of a display, the method comprising the steps of:

displaying a character and/or graphic pattern on said display;

detecting an environmental light intensity and generating a detection signal depending upon the detected light intensity;

calculating a time function of variation of the light intensity in response to said detection signal;

determining, in response to said time function of variation of the light intensity, a display brightness of said display in accordance with a time function of variation of a human pupil open degree; and

performing brightness control of said display according to the determined display brightness;

wherein said determining step includes;

preliminarily setting a pupil open degree variation time function table by predicting a time function of variation of human pupil open degree variation corresponding to said light intensity variation time function; and

preliminarily storing, in a display brightness table, display brightness information indicative of optimal display brightness of said display means corresponding to said pupil open degree variation time function.

5. The method according to claim 4, wherein said pupil open degree variation time function table is a read-only memory, and wherein said determining step includes:

using said light intensity variation time function as an address input; and

storing pupil open degree variation time functions respectively corresponding to the address inputs.

6. The method according to claim 5, wherein said display brightness table is a read-only memory, and wherein said determining step includes:

using the pupil open degree variation time function as an address input; and

storing said display brightness information corresponding to respective address inputs.