Semiconductor Device and Electronics Equipped Therewith

• US 20110051128A1
• Filed: 01/25/2010
• Published: 03/03/2011
• Est. Priority Date: 01/26/2009
• Status: Abandoned Application

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Horibe, Masao
• Application Number:
  US12/811,110
• Publication Number:
  US 20110051128A1
• Time in Patent Office: Days
• US Class Current: 356/218
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H05B 45/12 using optical feedback

Abstract

A semiconductor device (101) includes: a table unit (11) for receiving photodetection data indicating intensity of light, and outputting current data indicating a current value corresponding to a value of the photodetection data, the table unit having an association between the photodetection data and the current data stored therein in a fixed manner; a current adjustment unit (12) for adjusting the current value indicated by the current data in accordance with a variable parameter, and outputting adjusted current data indicating the current value adjusted; and a current supply unit (4) for supplying a load (53) with a current based on the adjusted current data.

Claims

1. A semiconductor device comprising:

a table unit for receiving photodetection data indicating an intensity of light, and outputting current data indicating a current value corresponding to a value of said photodetection data, said table unit having an association between said photodetection data and said current data stored therein in a fixed manner;

a current adjustment unit for adjusting said current value indicated by said current data in accordance with a variable parameter, and outputting adjusted current data indicating said current value adjusted; and

a current supply unit for supplying a load with a current based on said adjusted current data.

2. The semiconductor device according to claim 1, wherein:

said current adjustment unit adjusts said current value indicated by said current data in accordance with first to third variable parameters, and outputs said adjusted current data indicating said current value adjusted;

said first parameter indicates a value for multiplying said current value indicated by said current data;

said second parameter indicates a minimum value of said current to be supplied to said load;

said third parameter indicates a maximum value of said current to be supplied to said load; and

said current adjustment unit outputs said adjusted current data indicating a product of said current value indicated by said current data and said value indicated by said first parameter plus said minimum value indicated by said second parameter, and if said adjusted current data indicates a current value larger than said maximum value indicated by said third parameter, said current adjustment unit outputs adjusted current data indicating said maximum value.

3. The semiconductor device according to claim 2, wherein:

said table unit has a plurality of types of associations between said photodetection data and said current data stored therein in a fixed manner;

said parameter indicates what type of association said photodetection data and said current data have therebetween; and

said table unit outputs said current data indicating said current value corresponding to said value of said photodetection data in accordance with said parameter.

4. The semiconductor device according to claim 1, wherein:

said parameter indicates a value for multiplying said current value indicated by said current data; and

said current adjustment unit outputs adjusted current data indicating a product of said current value indicated by said current data and said value indicated by said parameter.

5. The semiconductor device according to claim 1, wherein:

said parameter indicates a minimum value of said current to be supplied to said load; and

said current adjustment unit outputs adjusted current data indicating a sum of said current value indicated by said current data and said minimum value indicated by said parameter.

6. The semiconductor device according to claim 1, wherein:

said parameter indicates a maximum value of said current to be supplied to said load; and

if said current data indicates a current value larger than said maximum value indicated by said parameter, said current adjustment unit outputs adjusted current data indicating said maximum value.

7. The semiconductor device according to claim 1, wherein:

said table unit has a plurality of types of associations between said photodetection data and said current data stored therein in a fixed manner;

said parameter indicates what type of association said photodetection data and said current data have therebetween; and

said table unit outputs said current data indicating said current value corresponding to said value of said photodetection data in accordance with said parameter.

8. The semiconductor device according to claim 1, further comprising:

a register for storing said photodetection data and said parameter; and

a signal input/output circuit for externally outputting said photodetection data stored in said register, and for externally receiving said parameter and providing said parameter to said register.

9. The semiconductor device according to claim 1, further comprising:

a voltage generation circuit for supplying an external photosensor with power supply voltage; and

a data generation unit for generating said photodetection data in accordance with a current output from said photosensor.

10. The semiconductor device according to claim 9, further comprising a gain control unit for controlling a gain of said photosensor in accordance with said photodetection data, wherein said data generation unit generates said photodetection data in accordance with said gain of said photosensor and said current output from said photosensor.

11. The semiconductor device according to claim 10, wherein said voltage generation circuit, said data generation unit and said gain control unit operate in a predetermined cycle intermittently.

12. The semiconductor device according to claim 1, further comprising:

an A/D converter for converting an analog voltage indicating an intensity of light to a digital signal in a predetermined first cycle; and

an averaging unit for averaging a plurality of digital signals generated in said A/D converter to generate said photodetection data.

13. The semiconductor device according to claim 12, wherein:

said A/D converter operates in a second cycle intermittently to generate said plurality of digital signals in each operation period, said second cycle being longer than said first cycle; and

said averaging unit averages said plurality of digital signals to generate said photodetection data whenever said A/D converter generates said plurality of digital signals.

14. The semiconductor device according to claim 1, wherein when said adjusted current data indicates that said current value adjusted has transitioned from a first current value to a second current value, said current supply unit gradually varies said current to be supplied to said load from said first current value to said second current value.

15. The semiconductor device according to claim 14, wherein a rate used to vary a value of said current to be supplied to said load is settable to a desired value.

16. The semiconductor device according to claim 1, wherein said current supply unit supplies said load with said current in accordance with said adjusted current data when a PWM signal has a first logic level, and said current supply unit stops supplying said load with said current when said PWM signal has a second logic level.

17. Electronics comprising:

a photosensor for outputting a current corresponding to an intensity of light incident thereon;

a light emitting element;

a data generation unit for outputting photodetection data based on said current output from said photosensor, and indicating said intensity of light incident on said photosensor;

a table unit for receiving said photodetection data and outputting current data indicating a current value corresponding to a value of said photodetection data, said table unit having an association between said photodetection data and said current data stored therein in a fixed manner;

a current adjustment unit for adjusting said current value indicated by said current data in accordance with a variable parameter, and outputting adjusted current data indicating said current value adjusted; and

a current supply unit for supplying said light emitting element with a current based on said adjusted current data.