Light quantity controller and input device

• US 4,467,246 A
• Filed: 08/20/1981
• Issued: 08/21/1984
• Est. Priority Date: 08/28/1980
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takeda, Hiroaki, Tanaka, Kano
• Primary Examiner(s): Laroche, Eugene R.
• Application Number:
  US06/294,572
• Time in Patent Office: 1,097 Days
• Field of Search: 315/129, 315/135, 315/136, 315/151, 315/158, 315/224, 315/226, 315/291, 315/307, 315/DIG. 7, 340/641, 323/353, 338/89, 338/118, 338/120
• US Class Current: 315/158
• CPC Class Codes: G03B 27/527 as a whole in a translatory movement
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A light quantity controller and an input device are disclosed. The light quantity controller comprises a light source, a photo-sensor to detect a light quantity of the light source, a signal source for generating a reference signal, a comparator for comparing the detected light amount with the reference signal, and control circuit to control a duty ratio of the energization to the light source in accordance with the compare result to maintain the light quantity of the light source at a constant level. The light quantity controller further comprises a comparator to compare the energization signal to the light source with a reference signal to detect the degradation of the light source. The input device has a key matrix including a plurality of input ports and a plurality of output ports of a control unit interconnected through switches. A signal source independent from the output ports of the key matrix is connected to at least one of the input ports through switches.

Claims

1. A light quantity controller comprising:

a light source adapted to emit light upon energization;

means for detecting the light quantity of said light source, and for producing a detection signal;

setting means for manually setting a desired light quantity of said light source, and for generating a reference signal in accordance with the light quantity set;

means for comparing the detection signal and the reference signal from said setting means, and for producing a comparison result as an output;

means for controlling an amount of an energization signal applied to said light source in accordance with the reference signal from said setting means; and

means for adding the output signal from said comparing means to the reference signal to be applied to said control means so that the light quantity detected by said detecting means becomes equal to the desired light quantity set by said setting means.

2. A light quantity controller according to claim 1 wherein said control means controls a duty ratio of the energization to said light source.

3. A light amount controller according to claim 1 further comprising means for indicating the degradation of said light source.

4. A light quantity controller according to claim 1 further comprising a high frequency power source for supplying power to said light source wherein said control means controls a conductive period of said power source.

5. A light quantity controller according to claim 4, wherein said light source comprises a flourescent lamp driven by said high frequency power source.

6. A light quantity controller according to claim 1, wherein said setting means has a manually movable member for setting a desired light quantity.

7. A light quantity controller comprising;

a light source adapted to emit light upon energization,

control means for generating a periodic signal to control the energization to said light source, and

means for determining a status of said signal to detect the degradation of said light source.

8. A light quantity controller according to claim 7 wherein said detection means includes means for generating a reference signal and comparing said control signal with said reference signal to detect the degradation.

9. A light quantity controller according to claim 7 wherein said detection means includes indication means for indicating the degradation of said light source.

10. A light quantity controller according to claim 7 wherein said control means controls a duty ratio of said periodic signal.

11. A light amount controller comprising;

a light source adapted to emit light upon energization,

means for detecting light quantity of said light source,

means for setting a light quantity to be maintained by said light source,

control means responsive to said detection means and said setting means for generating a first signal having a duty ratio to control the energization to said light source,

means for generating a second signal having a predetermined duty ratio, and

means for comparing to duty ratios of said first signal and said second signal to determine the degradation of said light source.

12. A light amount controller according to claim 11 further comprising a high frequency power source for supplying power to said light source, said power being controlled in accordance with the duty ratio of the first signal generated from said control means.

13. A light amount controller according to claim 11 wherein said comparing means determines a degradation of said light source, if the duty ratio of the first signal is larger than that of the second signal.

14. A light quantity controller comprising:

a light source adapted to emit light upon energization;

means for detecting a light quantity of said light source;

means responsive to an output from said detecting means for producing a driving signal to turn on said light source to a desired light quantity;

means for controlling a power supply to said light source based on the driving signal from said driving signal producing means; and

means for determining an improper status of said light source based on the output signal from said detecting means.

15. A light quantity controller according to claim 14 wherein said determining means has means for indicating the determination result.

16. A light quantity controller according to claim 14 further comprising means for manually setting the desired light quantity of said light source.

17. A light quantity controller according to claim 14 wherein said control means controls a period of the power supply to said light source in accordance with the driving signal.

18. A light quantity controller according to claim 14 wherein said light source is driven by a high frequency voltage.