US 7,512,160 B2
Control method of distributed Bragg reflection semiconductor laser, and image projecting apparatus
Kazunari Fujii, Atsugi (Japan); Hajime Sakata, Hamamatsu (Japan); and Yukio Furukawa, Sagamihara (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Aug. 30, 2007, as Appl. No. 11/896,142.
Application 11/896142 is a division of application No. 11/120951, filed on May 04, 2005, granted, now 7,313,156.
Claims priority of application No. 2004-142955 (JP), filed on May 12, 2004; and application No. 2005-055237 (JP), filed on Mar. 01, 2005.
Prior Publication US 2008/0002745 A1, Jan. 03, 2008
Int. Cl. H01S 3/10 (2006.01); H01S 5/00 (2006.01)
U.S. Cl. 372—21  [372/22; 372/50.11] 10 Claims
OG exemplary drawing
 
1. A control method of controlling a distributed Bragg reflection (DBR) semiconductor laser in an image projecting apparatus, wherein the image projecting apparatus includes the DBR semiconductor laser which is provided with a phase region and a DBR region, a light wavelength converting device for converting fundamental-wave light emitted from the DBR semiconductor laser into second harmonic wave light, an optical deflector for scanning the second harmonic wave light in a one-dimensional or two-dimensional manner, and a modulating portion for modulating the DBR semiconductor laser based on an image signal, said control method comprising:
a coefficient calculating step of calculating at least one coefficient in a relationship between a DBR current to be injected into the DBR region and a phase current to be injected into the phase region for continuously shifting the wavelength of the fundamental-wave light, within a non-drawing time during which a drawing signal, which corresponds to the image signal, is absent,
wherein the relationship between the DBR current and the phrase current is A·IDBR2+B·Iphase2=C where IDBR is the DBR current, Iphase is the phase current, A and B are proportional coefficients, respectively, and C is a constant; and
a wavelength adjusting step of changing the DBR current injected into the DBR region and the phase current injected into the phase region based on the relationship such that the second harmonic wave light is adjusted, within the non-drawing time, so as to stabilize the second harmonic wave light within a drawing time during which the drawing signal is present.