Control device, optical scanning device, display apparatus, and control method

Patent metadata

Field	Value
Publication number	US-11146764-B2
Application number	US-202016808867-A
Country	US
Kind code	B2
Filing date	Mar 4, 2020
Priority date	Mar 12, 2019
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

A control device for a laser scanning display apparatus includes a laser device, a current source that generates an electric current supplied to the laser device, and a controller that controls the current source to set a current value of the electric current supplied to the laser device. During a period for scanning a non-display area where no image is displayed, the controller sets the current value at a first drive current value that is less than a threshold current value at which the laser device starts oscillating; and during a period for scanning a portion with a luminance level of zero in a display area where an image is displayed, the controller sets the current value at a second drive current value that is greater than or equal to the first drive current value and less than the threshold current value.

First claim

What is claimed is:

1. A control device for a laser scanning display apparatus, the control device comprising:
a laser device;
a current source that generates an electric current supplied to the laser device; and
a controller that controls the current source to set a current value of the electric current supplied to the laser device, wherein
during a period for scanning a non-display area where no image is displayed, the controller sets the current value at a first drive current value that is greater than zero and less than a threshold current value at which the laser device starts oscillating;
during a period for scanning a portion with a luminance level of zero in a display area where an image is displayed, the controller sets the current value at a second drive current value that is greater than or equal to the first drive current value and less than the threshold current value;
the current source includes a first current source and a second current source;
the controller sets an electric current generated by the first current source at a first set current value that is “threshold current value×1/n (n is a number greater than one)” and sets an electric current generated by the second current source at a second set current value that is greater than the first set current value and less than “threshold current value×(1−1/n)”; and
the first drive current value is the first set current value, and the second drive current value is a sum of the first set current value and the second set current value.

2. The control device as claimed in claim 1 , wherein during a period for scanning a portion of the display area whose luminance level is not zero, the controller sets the current value at a third drive current value that is obtained by adding a gradation current value indicating luminance of a video signal to the second drive current value.

3. An optical scanning device, comprising:
the control device as claimed in claim 1 ; and
an optical scanner that scans a laser beam output from the laser device.

4. A display apparatus, comprising:
the optical scanning device as claimed in claim 3 ; and
an optical system that displays an image according to the laser beam scanned by the optical scanner.

5. A method for controlling a laser scanning display apparatus including a laser device and a current source that generates an electric current supplied to the laser device, the method comprising:
setting a current value of the electric current at a first drive current value, which is greater than zero and less than a threshold current value at which the laser device starts oscillating, during a period for scanning a non-display area where no image is displayed; and
setting the current value at a second drive current value, which is greater than or equal to the first drive current value and less than the threshold current value, during a period for scanning a portion with a luminance level of zero in a display area where an image is displayed, wherein
the current source includes a first current source and a second current source;
an electric current generated by the first current source is set at a first set current value that is “threshold current value×1/n (n is a number greater than one)”, and an electric current generated by the second current source is set at a second set current value that is greater than the first set current value and less than “threshold current value×(1−1/n)”; and
the first drive current value is the first set current value, and the second drive current value is a sum of the first set current value and the second set current value.

Assignees

• Tanaka Toyoki
• Hayakawa Etsuji
• Mitsumi Electric Co Ltd

Inventors

• Tanaka Toyoki
• Hayakawa Etsuji

Classifications

• H04N9/3164

  using multiple light sources · CPC title

• H04N9/3179

  Video signal processing therefor · CPC title

• H04N9/3194

  including sensor feedback · CPC title

• G09G3/346

  based on modulation of the reflection angle, e.g. micromirrors (micromirrors devices per se G02B26/0833) · CPC title

• G02B26/105 Primary

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title