Video device

Patent metadata

Field	Value
Publication number	US-11212423-B2
Application number	US-201816627914-A
Country	US
Kind code	B2
Filing date	Jun 1, 2018
Priority date	Sep 28, 2017
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

To propose an optical scanning method for a video device including an optical scanning unit in which one end of a light guide path has a protruding beam-shaped structure. The video device includes the optical scanning unit having the light guide path in which light enters from one end and emits from the other end, and a vibration unit configured to apply vibration to the light guide path via a joint unit in a vicinity of the other end of the light guide path; a drive signal generation unit that generates a drive signal for inducing vibration in the vibration unit; and a scanning trajectory control unit which has a function of independently vibrating the light guide path in a first direction substantially perpendicular to an optical axis direction of the light guide path, and in a second direction substantially perpendicular to the optical axis direction of the light guide path and substantially perpendicular to the first direction by the vibration unit, and which generates a first drive signal configured to drive the vibration unit in the first direction and a second drive signal configured to drive the vibration unit in the second direction with any pattern. The scanning trajectory control unit generates the first drive signal and the second drive signal as sine waves having different phases and a substantially same frequency, and sets a modulation amount of an amplitude modulation of a sine wave of the second drive signal to be larger than a modulation amount of an amplitude modulation of a sine wave of the first drive signal.

First claim

The invention claimed is:

1. A video device comprising:
an optical scanning unit including a light guide path in which light enters from one end and emits from another end, and a vibration unit configured to apply vibration to the light guide path via a joint unit in a vicinity of the other end of the light guide path, wherein the vibration unit is configured to independently vibrate the light guide path in a first direction substantially perpendicular to an optical axis direction of the light guide path, and in a second direction substantially perpendicular to the optical axis direction of the light guide path and substantially perpendicular to the first direction;
a drive signal generation unit configured to generate drive signals for inducing vibration in the vibration unit;
a scanning trajectory control unit configured to determine a pattern of a first drive signal that drives the vibration unit in the first direction and a second drive signal that drives the vibration unit in the second direction, output information on the pattern of the first and second drive signals to the drive signal generation unit, and output a synchronization signal for optical scanning;
a video control unit configured to calculate optical scanning position coordinates based on the synchronization signal received from the scanning trajectory control unit, read pixel data corresponding to the optical scanning position coordinates from video information to be projected, and transmit the pixel data; and
a light emission control unit configured to generate signals to modulate a light source unit according to the pixel data received from the video control unit;
wherein the light source unit is configured to inject light into the light guide path; and
wherein the scanning trajectory control unit generates the first drive signal and the second drive signal as sine waves having 90° different phases and a substantially same frequency, gradually increases the amplitude of the second drive signal with time during a vibration period, decays the amplitude with time or sets the amplitude to zero during a decay period, and sets the amplitude of the first drive signal to an approximately constant value.

2. The video device according to claim 1 , wherein
a cycle in which the light emission control unit modulates the light source unit is sufficiently smaller by 2 to 4 digits enough to obtain a sufficient resolution in the first direction than a cycle of the sine wave of the first drive signal.

3. The video device according to claim 2 , wherein
the cycle of the sine wave of the first drive signal is an integer multiple of the cycle in which the light emission control unit modulates the light source unit.

4. The video device according to claim 2 , wherein
the cycle of the sine wave of the first drive signal is a sum of an integer multiple of the cycle in which the light emission control unit modulates the light source unit and a half of the cycle.

5. The video device according to claim 1 , wherein
a maximum modulation amplitude of the sine wave of the first drive signal is larger than a maximum modulation amplitude of the sine wave of the second drive signal, and optical scanning is performed on an elliptical area which effectively encompasses a rectangular aspect ratio video display area of a video format.

Assignees

• Hitachi Ltd

Inventors

• Matsuda Takahiro
• Seo Yoshiho
• Ouchi Satoshi
• Onoe Shinsuke

Classifications

• H04N23/56

  provided with illuminating means · CPC title

• H04N5/76

  Television signal recording · CPC title

• H04N9/3135

  Driving therefor · CPC title

• G02B6/0008

  the light being emitted at the end of the fibre · CPC title

• G02B26/103 Primary

  having movable or deformable optical fibres, light guides or waveguides as scanning elements (light guides per se G02B6/00) · CPC title