SEPARATE-TYPE DETECTOR

• US 20090026354A1
• Filed: 02/23/2006
• Published: 01/29/2009
• Est. Priority Date: 02/23/2006
• Status: Active Grant

• Current Assignee: Hochiki Corporation
• Original Assignee: Hochiki Corporation
• Inventors: Nakajima, Satoshi, Itou, Masayuki
• Granted Patent: US 7,968,837 B2
• Time in Patent Office: Days
• US Class Current: 250/216
• CPC Class Codes: G01N 21/534 by measuring transmission alone, i.e. determining opacity
• CPC Class Codes: G08B 17/103 using a light emitting and receiving device

Abstract

[Object] An object is to provide a separated sensor capable of synchronizing a light transmitting unit with a light receiving unit, without using a control line.

[Solving means] There is provided a separated sensor including a light transmitting unit that transmits detection light to a monitoring area, and a light receiving unit that receives detection light transmitted by the light transmitting unit, the light transmitting unit and the light receiving unit laid out separately from each other. On one of the light transmitting unit and the light receiving unit, there is provided a synchronization-light transmitting unit that transmits, by wireless, synchronization light to synchronize the light transmitting unit with the light receiving unit. On the other of the light transmitting unit and the light receiving unit, there are provided a synchronization-light receiving unit that receives the synchronization light transmitted from the synchronization-light transmitting unit, and a synchronization-establishment processing unit that performs a predetermined process to establish the synchronization based on the synchronization light received by the synchronization-light receiving unit.

Claims

1. A separated sensor comprising a light transmitting unit that transmits detection light to a monitoring area, and a light receiving unit that receives detection light transmitted by the light transmitting unit and determines presence of a predetermined monitoring object in the monitoring area, based on a detection amount of the received detection light, the light transmitting unit and the light receiving unit laid out separately from each other, wherein

a synchronization-light transmitting unit that transmits, by wireless, synchronization light to synchronize the light transmitting unit with the light receiving unit is provided, on one of the light transmitting unit and the light receiving unit, and

a synchronization-light receiving unit that receives the synchronization light transmitted from the synchronization-light transmitting unit and a synchronization-establishment processing unit that performs a predetermined process to establish the synchronization based on the synchronization light received by the synchronization-light receiving unit are provided, on the other of the light transmitting unit and the light receiving unit.

2. The separated sensor according to claim 1, wherein the synchronization-light transmitting unit is provided in the light transmitting unit, and the synchronization-light receiving unit and the synchronization-establishment processing unit are provided in the light receiving unit,

the synchronization-light transmitting unit transmits the detection light as the synchronization light,

the synchronization-light receiving unit receives the detection light as the synchronization light, and

the synchronization-establishment processing unit performs a predetermined process to establish synchronization based on the detection light received by the synchronization-light receiving unit.

3. The separated sensor according to claim 2, wherein the synchronization light transmitting unit intermittently transmits the detection light by only a predetermined light-transmission time at each predetermined light transmission interval, and

the synchronization-establishment processing unit intermittently performs the light reception operation by only a predetermined light-reception time at each predetermined light reception interval different from the light transmission interval and determines presence of reception of the detection light during this light reception operation, and when it is determined that the detection light is received, the synchronization- establishment processing unit specifies, as a synchronization timing, a timing arriving at the predetermined light transmission interval based on the timing of receiving the detection light.

4. The separated sensor according to claim 3, wherein the light reception interval is set shorter than the light transmission interval.

5. The separated sensor according to claim 3, wherein the light reception interval is set longer than the light transmission interval.

6. The separated sensor according to claim 3, wherein the synchronization-establishment processing unit changes the reception time of the detection light to a predetermined second light-reception time shorter than the light reception time, after specifying the synchronization timing.

7. The separated sensor according to claim 1, wherein an amplifier that amplifies the output from the synchronization-light receiving unit corresponding to the reception amount of the synchronization light is provided in the other of the light transmitting unit and the light receiving unit, and

the synchronization-establishment processing unit starts the amplifier, and after passing a predetermined time when the output from the amplifier is stabilized, determines presence of a reception of the synchronization light based on the output from the amplifier.

8. The separated sensor according to claim 1, wherein an amplifier that amplifies the output from the synchronization-light receiving unit corresponding to the reception amount of the synchronization light is provided in the other of the light transmitting unit and the light receiving unit, and

the synchronization-establishment processing unit determines presence of a reception of the synchronization light by setting the amplifier to a maximum amplification rate, and after establishing the synchronization, resets the amplifier to a predetermined amplification rate smaller than the maximum amplification rate.

9. The separated sensor according to claim 1, comprising a synchronization-correction processing unit that performs a predetermined process of correcting the synchronization timing based on the synchronization light received by the synchronization-light receiving unit, after the synchronization-establishment processing unit establishes synchronization.

10. The separated sensor according to claim 9, wherein the synchronization-correction processing unit compares the reception amount of the synchronization light received by the synchronization-light receiving unit with a predetermined value, thereby determining whether the synchronization light of a reception amount of a predetermined value or larger is received, and when the number of times when the synchronization light of a reception amount of the predetermined value or larger is not received becomes a predetermined number of times or larger, the synchronization-correction processing unit starts the synchronization establishment process by the synchronization-establishment processing unit or performs a predetermined process of notifying the occurrence of a correction trouble.

11. The separated sensor according to claim 9, wherein the synchronization-correction processing unit compares the reception amount of the synchronization light received by the synchronization-light receiving unit with a predetermined value, and when the synchronization light of the predetermined value or larger is received, the synchronization-correction processing unit sets, as a synchronization timing, the timing arriving at the predetermined light transmission interval based in the timing of receiving this synchronization light.