JPH077075B2 - Back ground removal device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a background removal device that separates background light from the light detected by an optical sensor that is a non-contact sensor.

2. Description of the Related Art Generally, when an object to be measured is detected by an optical sensor, a background signal when the object to be measured does not exist needs to be removed from detection light when the object to be measured exists.

FIG. 3 shows the structure of a conventional background removing device. In FIG. 3, 1 is a light receiving element of an optical sensor, 2 is an averaging circuit, 3 is a background signal calculation unit, 4 is a background signal memory, 5 is a subtractor, 6 is an external memory for a microcomputer, and 7 is a micro. It is a computer.

In FIG. 3, the light receiving element 1 detects light from the object to be measured. The averaging circuit 2 averages the signals of the light receiving element 1 to remove the influence of noise. The background signal calculation unit 3 calculates the background signal based on the output of the averaging circuit 2. This background signal is a background signal when there is no measurement object. The memory 4 stores the background signal and outputs it to the subtractor 5. The subtractor 5 takes the difference between the output of the light receiving element 1 and the output of the memory 4. In this way, even the background removal device of the related art can remove the influence of the background light from the detection light.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described background removal device, it is impossible to remove the influence of background light while updating the contents of the memory that stores the background signal, and therefore, there is always a real-time target. There is a problem that the measured object cannot be detected.

The present invention solves such a conventional problem, and an object of the present invention is to provide an excellent background removal device capable of continuing measurement without interruption.

Means for Solving the Problems In order to achieve the above object, the present invention has one of a first and a second memory for storing a background signal and one of a first and a second memory in a write state and the other is read. A control means for switching to the state is provided.

According to the present invention, one of the memories for storing the background signal is dedicated to reading and the other is dedicated to writing, so that the background signal can be read and updated at the same time, so that the background signal can be always removed.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention. In FIG. 1, 11 is a light receiving element, 12 is an averaging circuit, 13 is a background signal calculator, 14 and 15 are background signal memories, 16 is a subtractor, 17 is an external memory for a microcomputer, and 18 is a micro. The computer, 19 is an inverter.

Next, the operation of the above embodiment will be described. In the above embodiment, the averaging circuit 12 averages the signals of the light receiving element 11. The background signal calculation unit 13 calculates the background signal based on the output of the averaging circuit 12. This background signal is the signal of the detection light when there is no object to be measured. The background signal memories 14 and 15 have a function of storing the background signal and outputting it to the subtractor 16, and the microcomputer 18 determines the writing or reading state. The memories 14 and 15 input and store the background signal in the write state, and output the stored background signal to the subtractor 16 in the read state. Memory 14 and
15 is determined by the microcomputer 18 and the inverter 19 so that when one is in the written state, the other is in the read state. The subtractor 16 subtracts the light receiving element 11 and the background signal.

This timing diagram of FIG. 2 is shown. In FIG. 2, when the memory is read, it is read and when it is written, it is written. In FIG. 2, (a) is a read / write control signal from the microcomputer, (b) is a read / write terminal signal of the memory 14, and (c) is a read / write terminal signal of the memory 15.

As described above, according to the above-described embodiment, there is an effect that the background signal can be always removed without interruption.

As is apparent from the above-described embodiment, the present invention has two background signal storage memories whose reading and writing states are opposite to each other, so that the background from the averaged detection signal of the optical sensor is obtained. This has the effect that the signal can be always removed and the background signal can be updated freely.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a background removing device according to an embodiment of the present invention, FIG. 2 is a timing diagram of the device, and FIG. 3 is a schematic block diagram of a conventional background device. 11 ... Light receiving element, 12 ... Averaging circuit, 13 ... Background calculation circuit, 14,15 ... Background signal memory, 16 ... Subtractor, 17 ... Microcomputer external memory, 18 ... Microcomputer.

Claims (1)

[Claims] 1. An averaging circuit for averaging optical sensor signals, a background signal calculating section for calculating a background signal based on the output of the averaging circuit, and first and second recording the background signals. Second memory, a subtracter for subtracting the signal read from the first or second memory and the photosensor signal, and one of the first and second memories in a writing state and the other in a reading state And a control means for performing the arithmetic mean of the photosensor signals, and constantly removing the background signal by the first and second memories.