Patent ID: 11862740
Assignee: ROHM CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. An illuminance sensor, comprising:
a first light receiving portion and a second light receiving portion;
a first optical region and a second optical region, disposed corresponding to the first light receiving portion and the second light receiving portion respectively; and
a difference detecting portion, obtaining a difference between outputs of the first light receiving portion and the second light receiving portion,
wherein the first optical region and the second optical region comprise a first linear polarization plate, a first quarter-wave plate, a second quarter-wave plate and a second linear polarization plate corresponding to both the first light receiving portion and the second light receiving portion, and disposed sequentially in an order that the first linear polarization plate is farthest from the first light receiving portion and the second light receiving portion,
an ineffective band of either one or both of the first and second linear polarization plates comprises at least a portion of an infrared band,
the first quarter-wave plate comprises a first portion and a second portion, wherein the first portion is in the first optical region and the second portion is in the second optical region,
a slow axis of the first portion comprises a relation of +45° or −45° in regard to a first polarization direction that is a polarization direction of the first linear polarization plate,
a relation of a slow axis of the second portion in regard to the first polarization direction is −45° or +45° that is opposite in sign to the relation of the slow axis of the first portion in regard to the first polarization direction, and
a slow axis of the second quarter-wave plate comprises a relation of +45° or −45° in regard to a second polarization direction that is a polarization direction of the second linear polarization plate, wherein the relation of the slow axis of the second quarter-wave plate in regard to the second polarization direction is the same with the relation of the slow axis of the first portion in regard to the first polarization direction.