Light source device, projector device, monitor device, and lighting device

• US 20080165815A1
• Filed: 01/02/2008
• Published: 07/10/2008
• Est. Priority Date: 01/09/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kamijima, Shunji
• Granted Patent: US 7,733,931 B2
• Time in Patent Office: Days
• US Class Current: 372/34
• CPC Class Codes: G02F 1/3546 Active phase matching, e.g. by electro- or thermo-optic tuning
• CPC Class Codes: G02F 2203/60 Temperature independent
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 5/0617 using memorised or pre-programmed laser characteristics
• CPC Class Codes: H01S 5/06804 by monitoring an external parameter, e.g. temperature
• CPC Class Codes: H01S 5/14 External cavity lasers H01S5/18 takes precedence; mode locking H01S5/065
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

The controller 170 controls the output power of the semiconductor laser device 100a depending on the temperature of the semiconductor laser device 100a acquired by the temperature sensor 130. The controller 170 references the correspondence table 510 when the sensor temperature Ts is obtained, obtains the output power PWs corresponding to the sensor temperature Ts, and controls the power supply driving circuit 150a so that the output power per unit time of the semiconductor laser device 100a will be the output power PWs. Thus increase in temperature of the semiconductor laser device is able to be prevented through reducing the output power by controlling the amount of power supplied to the semiconductor laser device. As a result, it is possible to prevent reductions in the service life of the semiconductor laser device, even when there is a failure in a cooling device that cools the semiconductor laser device, and even when the device is used in a high temperature environment not envisioned at the time of manufacturing.

Claims

1. A light source device, comprising:

a light source that emits a laser beam;

a driving circuit that supplies electric power for driving the light source;

an acquirer that acquires the temperature of the light source; and

a controller that controls the driving circuit so as to reduce the power supplied per unit time to the light source from the driving circuit when the acquired light source temperature is greater than a first predetermined threshold value.

2. A light source device as in accordance with claim 1, further comprising:

a memory that stores relational information for relating the light source temperature with a target power to be supplied to the light source, wherein;

the controller controls the driving circuit using the acquired light source temperature and the relational information.

3. A light source device as in accordance with claim 2, wherein:

the relational information includes a target power table for correlating the light source temperature and the target power; and

the controller controls the driving circuit using the light source temperature and the target power table.

4. A light source device as in accordance with claim 1, wherein:

the controller controls the driving circuit so as to change the power supplied per unit time to the light source so that the amount of change in brightness of the light source, relative to the brightness of the light source prior to the reduction in the power, changes at a slope of no more than 2% per 1/60 second.

5. A light source device as in accordance with claim 1, wherein:

the controller controls the driving circuit so as to increase the power supplied per unit time to the light source from the driving circuit when the acquired light source temperature is lower than a second threshold value, wherein the second threshold is lower than the first threshold value.

6. A light source device as in accordance with claim 5, wherein:

the controller controls the driving circuit, when increasing the power supplied per unit time to the light source from the driving circuit, so that the change in the power supplied per unit time to the light source will be such that the amount of change in brightness of the light source, relative to the brightness of the light source prior to the increase of the power, changes at a slope of no more than 2% per 1/60 second.

7. A light source device as in accordance with claim 2, wherein:

the controller controls the driving circuit when starting up the driving circuit so that the power supplied per unit time to the light source will be the target power.

8. A light source device as in accordance with claim 4, wherein:

the controller estimates a steady-state temperature using the amount of change of the temperature of the light source over a predetermined time period, wherein the steady-state temperature is the light source temperature that has reached a steady state, and controls the driving circuit so that the power supplied per unit time to the light source relative to the predetermined target power based on the estimated steady-state temperature and the target power table, so that the brightness changes along the slope.

9. A light source device as in accordance with claim 1, wherein:

the controller controls the driving circuit depending on the changed light source temperature when the light source temperature has changed more than a predetermined amount of change within a determined time period.

10. A light source device as in accordance with claim 2, wherein:

the relational information includes a first portion wherein, when the target power at a first temperature is defined as a first target power, the target power at the second temperature that is lower than the first temperature is defined as a second target power, and the target power at a third temperature that is lower than the second temperature is defined as a third target power, the ratio of the difference between the first temperature and the second temperature to the difference between the first target power and the second target power is larger than the ratio of the difference between the second temperature and the third temperature to the difference between the second target power and the third target power.

11. A light source device as in accordance with claim 10, wherein:

the relational information includes a second portion wherein the target power relative to a temperature at or above a fourth temperature, wherein the fourth temperature is higher than the first temperature, is zero.

12. A light source device as in accordance with claim 1, wherein:

the driving circuit supplies the power through pulse modulation; and

the controller reduces the power through controlling the driving circuit so as to either reduce the width of the pulse that is generated by the pulse modulation or to reduce the amplitude of the pulse that is generated by the pulse modulation.

13. A light source device as in accordance with claim 1, further comprising:

a beam intensity acquirer that acquires the beam intensities of a beam emitted from the light source, wherein;

the controller implement controls based on the light source temperature and the beam intensities.

14. A light source device as in accordance with claim 1, wherein:

the light source device is, as the light source, provided with a red light source for outputting red light, a green light source for outputting green light, and a blue light source for outputting blue light;

the controller controls the driving circuit, based on a reference temperature, so as to reduce the power supplied to a reference light source and to reduce the power supplied to other light sources in coordination with the reduction of the reference light source power of the red light source, the green light source, and the blue light source, wherein the reference temperature is the highest light source temperature among the light source temperatures of the red light source, the green light source, and the blue light source, wherein the reference light source has the highest reference temperature.

15. A light source device as in accordance with claim 14, wherein:

the controller controls the driving circuit so as to maintain at a constant level the white balance of the light that is outputted from each of the colored light sources.

16. A light source device as in accordance with claim 15, wherein:

the controller controls the driving circuit so that the power supplied per unit time to each of the colored light sources is no more than the power when at the maximum brightness for each colored light source.

17. A light source device as in accordance with claim 16, wherein:

the controller controls the driving circuit so as to change, in coordination with the power of an un-achieved light source from among all of the light sources, the power of the other light sources wherein the un-achieved light source is unable to achieve a predetermined brightness.

18. A light source device as in accordance with claim 17, wherein:

the controller controls the driving circuit so as to maintain the white balance uniformly based on the brightness of the red light source.

19. An image display device comprising the light source device in accordance with claim 1.

20. A monitor device comprising the light source device in accordance with claim 1.

21. A lighting device provided with the light source device in accordance with claim 1.