Light sensitivity controlling apparatus and projection-type display device equipped with same

Patent metadata

Field	Value
Publication number	US-9532017-B2
Application number	US-201314094171-A
Country	US
Kind code	B2
Filing date	Dec 2, 2013
Priority date	Dec 6, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

The light sensitivity controlling apparatus comprises an optical semiconductor, an amplifier element, a resistor unit, an A/D converter, and a controller. The optical semiconductor receives a plurality of colors of light emitted from a light source in a time division. The amplifier element converts optical current flowing to the optical semiconductor into voltage by receiving the plurality of colors of light. The resistor unit switches the gain for converting the optical current inputted to the amplifier element into voltage, for each of the plurality of colors of light. The A/D converter converts the voltage outputted by the amplifier element from an analog signal into a digital signal. The sensitivity controlling apparatus controls the resistor unit so that the output level corresponding to the various colors of light outputted from the A/D converter will remain substantially same level.

First claim

The invention claimed is:

1. A light sensitivity controlling apparatus, comprising:
an optical semiconductor configured to receive a plurality of colors of light emitted from a light source in a time division;
an amplifier element configured to convert optical current flowing to the optical semiconductor into voltage by receiving the plurality of colors of light;
a resistor unit configured to switch the gain for converting the optical current inputted to the amplifier element into voltage, corresponding to each of the plurality of colors of light;
an A/D converter configured to convert the voltage outputted by the amplifier element from an analog signal into a digital signal; and
a controller configured to control the resistor unit so that the output level corresponding to the various colors of light outputted from the A/D converter remains substantially at the same level.

2. A light sensitivity controlling apparatus according to claim 1 , wherein the resistor unit has a variable resistance.

3. A light sensitivity controlling apparatus according to claim 1 , wherein the resistor unit is configured such that one or more circuits comprising a resistor and a switch connected in series are disposed in parallel.

4. A light sensitivity controlling apparatus according to claim 1 , further comprising:
a sample holder configured to hold an output voltage value outputted from the amplifier element; and
a selector configured to switch the output of the sample holder on the basis of a control signal from the controller, and outputs this to the A/D converter.

5. A projection-type display device, comprising:
the light sensitivity controlling apparatus according to claim 1 ;
a light source configured to emit a plurality of colors of light; and
a voltage application unit configured to apply a reference voltage to the optical semiconductor.

Assignees

• Panasonic Corp
• Panasonic Ip Man Co Ltd

Inventors

• Gyoten Takaaki

Classifications

• G03B21/2013

  Plural light sources · CPC title

• G03B33/08

  Sequential recording or projection (G03B33/02, G03B33/04, G03B33/06 take precedence) · CPC title

• H04N9/3114

  by using a sequential colour filter producing one colour at a time · CPC title

• H04N9/3194

  including sensor feedback · CPC title

• G01J1/44

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title