JP2008010677A - Detecting sensor and ic therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IC for a detecting sensor, and the detecting sensor capable of reducing the noise mixed into a detected signal. <P>SOLUTION: A light detecting IC 20 has a first switch SW1 between a preamplifier 22 and a main amplifier 23 in a circuit for transmitting a light-reception signal. External terminals P1, P2 for connection to a light-receiving sensitivity adjusting variable resistor 14 etc. are connected with the first switch SW1. Further, a second and a third switches SW2, SW3 are provided between the first switch SW1 and the external terminals P1, P2. The first switch SW1 and the second and the third switches SW2, SW3 are complementarily turned on and off. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a detection sensor IC and a detection sensor, and more particularly to a detection sensor IC and a control means for noise mixed in the detection sensor.

  A detection sensor such as a photoelectric sensor detects a workpiece based on a set detection threshold level with respect to a change in a received light signal depending on the presence or absence of an object (work). Some photoelectric sensors use an IC (hereinafter referred to as a light detection IC) on which a light receiving element and a processing circuit are mounted in order to reduce the size of the apparatus. Depending on the purpose and application of the photoelectric sensor, there are some operators (users) who need to adjust the photosensitivity of the photoelectric sensor, and others that do not need to be adjusted. There was a demand to manufacture a photoelectric sensor with a detection IC.

Therefore, as shown in FIG. 4, there is known a photoelectric sensor that adjusts light receiving sensitivity by externally attaching a light receiving sensitivity adjusting variable resistor 14 between a preamplifier 51 and a main amplifier 52 in a light detection IC 50. (For example, refer to Patent Document 1). When creating a product that does not require adjustment of the light receiving sensitivity, a wiring 53 (one-dot chain line in FIG. 4) is used between the external terminals P1 and P2 to which the external light receiving sensitivity adjusting variable resistor 14 is connected. Short circuit.
Japanese Patent No. 3783618

  However, in the above-mentioned Patent Document 1, in the photoelectric sensor that does not need to adjust the light receiving sensitivity, the external light receiving sensitivity adjusting variable resistor 14 is not connected and the external terminals P1 and P2 are short-circuited. Since the wiring length to the amplifier 52 becomes long and the wiring is arranged outside the IC, there is a problem that noise is easily mixed in the light reception signal.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a detection sensor IC and a detection sensor that can reduce noise mixed in a detection signal.

  In order to achieve the above object, the invention described in claim 1 is directed to a physical quantity detection means for outputting a detection signal at a level corresponding to a physical quantity for detecting an object to be detected, and the detection output from the physical quantity detection means. A detection sensor IC including an amplification circuit that amplifies the detection signal output from the physical quantity detection means. The first switch means for short-circuiting or opening a part of the path from the physical quantity detection means to the determination means via the amplifier circuit, and the first switch portion short-circuited or opened by the first switch means are electrically connected. A pair of external terminals, wherein the first switch means is switched between short-circuit and open-circuit by external control.

  According to the above configuration, when the first switch portion is short-circuited by the first switch means, the detection signal is transmitted inside the IC and does not need to go through the external terminal of the detection sensor IC. , Noise mixed in the detection signal can be reduced. Further, when the first switch portion is opened by the first switch means, it is possible to use a component connected to the external terminal with the same kind of detection sensor IC.

  According to a second aspect of the present invention, in the detection sensor IC according to the first aspect, the amplifier circuit includes a preamplifier and a main amplifier, and the first switch portion includes the preamplifier and the main amplifier. Between the main amplifiers.

  According to the above configuration, since the first switch portion is between the preamplifier and the main amplifier, the detection signal level can be amplified by the preamplifier before the detection signal is transmitted to the outside of the detection sensor IC. And the influence of noise can be reduced. Further, since the detection signal level can be adjusted before being input to the main amplifier, the adjustable range can be widened.

  According to a third aspect of the present invention, in the detection sensor IC according to the first or second aspect, the first switch portion and the pair of external terminals are connected by an operation complementary to the first switch means. A pair of second switch means for short-circuiting or opening is provided.

  According to the above configuration, when the first switch means is short-circuited, the second switch means is opened, so that the external terminal and the amplifier circuit are separated. Therefore, it is possible to prevent noise from entering the detection signal from the external terminal. Further, since the second switch means is short-circuited when the first switch means is opened, it is possible to use a component connected to the external terminal with the same kind of detection sensor IC.

  According to a fourth aspect of the present invention, there is provided a physical quantity detection means for outputting a detection signal at a level corresponding to a physical quantity for detecting an object to be detected, and the detection target based on the detection signal output from the physical quantity detection means. A detection sensor including a determination unit configured to determine an object, an amplification circuit for amplifying the detection signal output from the physical quantity detection unit, and a path from the physical quantity detection unit to the determination unit via the amplification circuit A first switch means for short-circuiting or opening a part of the first switch means, and a pair of external terminals electrically connected to the first switch part short-circuited or opened by the first switch means, And switching means for switching between short circuit and open of the first switch means.

  According to the above configuration, when the first switch portion is short-circuited by the first switch means, the detection signal is transmitted inside the IC, so that noise mixed in the detection signal can be reduced. Further, when the first switch portion is opened by the first switch means, it is possible to use a component connected to the external terminal with the same kind of detection sensor IC.

  According to a fifth aspect of the present invention, in the detection sensor according to the fourth aspect, the first switch portion is opened by the first switch means, and a detection signal level adjusting means is connected to the pair of external terminals. It is what is done.

According to the said structure, the detection sensor which can adjust a detection signal level can be provided.
According to a sixth aspect of the present invention, in the detection sensor according to the fourth aspect, the first switch portion is short-circuited by the first switch means, and the pair of external terminals are opened.

According to the said structure, the detection sensor with small noise mixed in a detection signal can be provided.
According to a seventh aspect of the present invention, in the detection sensor according to any one of the fourth to sixth aspects, the detection sensor is provided between the first switch portion and the pair of external terminals. It comprises a pair of second switch means that are short-circuited or opened in a complementary manner with one switch means.

  According to the above configuration, when the first switch means is short-circuited, the second switch means is opened, so that the external terminal is disconnected from the circuit in the detection IC, and noise is mixed into the detection signal from the external terminal. It becomes possible to prevent. Further, since the second switch means is short-circuited when the first switch means is opened, it is possible to use a component connected to the external terminal with the same kind of detection sensor IC.

  ADVANTAGE OF THE INVENTION According to this invention, IC for detection sensors and a detection sensor which can reduce the noise mixed in a detection signal can be provided.

Hereinafter, an embodiment in which the present invention is embodied in a beam sensor as a detection device will be described with reference to FIGS.
FIG. 1A is a perspective view of a beam sensor 10 of the present embodiment. A main body 11 of the beam sensor 10 is formed in a substantially rectangular parallelepiped shape and is connected to a cable 12 connected to an external device (not shown). A light receiving sensitivity adjusting variable resistor 14 as a light receiving sensitivity adjusting means is disposed on the side surface 13 of the main body 11 so as to be exposed. As shown in FIG. 1B, a light projecting element 15 made up of an LED (light emitting diode) is installed in the beam sensor 10 and a printed circuit board 16 is disposed. The printed circuit board 16 receives incident light. A light detection IC 20 for receiving light is mounted. A lens 17 is installed on the bottom surface of the main body 11 so as to face the light projecting element 15 and the light detection IC 20.

  As shown in FIG. 2, a window 20a for allowing light to enter the inside of the light detection IC 20 is formed on the upper surface of the light detection IC 20, and the light detection IC 20 corresponds to the window 20a. A photodiode PD as a physical quantity detecting means shown in FIG. The anode of the photodiode PD is connected to the ground GND, and the cathode is connected to the power supply Vcc via the resistor R1 and to the I / V converter 21. The output terminal of the I / V converter 21 is connected to the preamplifier 22, and the I / V converter 21 converts the photocurrent input from the photodiode PD into a voltage and outputs the voltage to the preamplifier 22. To do.

  The preamplifier 22 amplifies the input voltage and outputs it. The output terminal of the preamplifier 22 is connected to one end of the first switch SW1 and the second switch SW2, and the other end of the first switch SW1 is connected to the main amplifier 23 via the coupling capacitor C1, and other than the second switch SW2. The end is connected to the external terminal P1. The other end of the first switch SW1 is connected to one end of the third switch SW3, and the other end of the third switch SW3 is connected to the external terminal P2. Both external terminals P1 and P2 are connected to connection terminals P11 and P12 of the printed circuit board, and a variable resistor 14 for adjusting light receiving sensitivity is connected between the connection terminals P11 and P12. The first switch SW1 constitutes a first switch means, and the second and third switches SW2 and SW3 constitute a pair of second switch means.

  The output terminal of the main amplifier 23 is connected to a comparator 24 as a discrimination means. The main amplifier 23 amplifies a signal input via the coupling capacitor C1 and outputs the amplified signal to the comparator 24. The comparator 24 is connected to an output circuit 25, and the comparator 24 compares an input signal (voltage) with a reference voltage, and outputs a binary signal corresponding to the comparison result to the output circuit 25. The output circuit 25 is connected to the outside and outputs an input signal to the outside.

  The light receiving sensitivity adjustment variable resistor 14 has two fixed terminals and one movable terminal. The first fixed terminal is connected to the connection terminal P11, the second fixed terminal is connected to the ground GND, and the movable terminal. Is connected to the connection terminal P12. Therefore, the light receiving sensitivity adjusting variable resistor 14 has a resistance value between the first fixed terminal and the movable terminal and a resistance value between the movable terminal and the second fixed terminal according to the adjustment position of the movable terminal. And the output voltage of the preamplifier 22 is divided by both resistance values. As a result, the voltage input to the main amplifier 23 is changed by the light receiving sensitivity adjustment variable resistor 14 and the voltage output from the main amplifier 23 is adjusted. The preamplifier 22 and the main amplifier 23 constitute an amplifier circuit using the preamplifier 22 as a preamplifier and the main amplifier 23 as a main amplifier.

  The first switch SW1 and the second and third switches SW2 and SW3 are composed of different conductivity type MOS transistors, and are connected to a fourth switch SW4 mounted on the printed circuit board 16. The fourth switch SW4 includes, for example, three pins mounted on the printed circuit board 16 and a short bar that short-circuits two of the pins, and switches on / off of the first switch SW1 and the second and third switches SW2, SW3. The switching means is configured. The first pin is connected to the power supply Vcc, the second pin is connected to the first to third switches SW1 to SW3, and the third pin is connected to the ground GND. The short bar short-circuits between the first pin and the second pin or between the second pin and the third pin. With this configuration, the control signal S1 at the power supply Vcc level (H level) or the ground GND level (L level) is supplied to the first to third switches SW1 to SW3, and the beam sensor with and without the light receiving sensitivity is adjusted. A single type of light detection IC can be used.

  The first switch SW1 and the second and third switches SW2 and SW3 are complementarily turned on and off in response to the control signal S1. Specifically, when the control signal S1 is at the H level (a beam sensor without adjusting the light receiving sensitivity), the first switch SW1 is turned on, and the second and third switches SW2 and SW3 are turned off. Conversely, when the control signal S1 is at L level (a beam sensor with adjustment of light reception sensitivity), the first switch SW1 is turned off and the second and third switches SW2 and SW3 are turned on.

The operation of the beam sensor 10 configured as described above will be described.
In the manufacturing process of the beam sensor 10, since the second switch and the third pin of the fourth switch SW4 are short-circuited by the short bar, the L level control signal S1 is supplied to the photodetection IC 20 during operation, and the control is performed. By the signal S1, the first switch SW1 is turned off, and the second and third switches SW2 and SW3 are turned on. Accordingly, the signal output from the preamplifier 22 is input to the light receiving sensitivity adjusting variable resistor 14 via the second switch SW2, the external terminal P1, and the connection terminal P11. The voltage signal divided to a desired value by the variable sensitivity for light receiving sensitivity adjustment 14 is input to the main amplifier 23 via the connection terminal P12, the external terminal P2, the third switch SW3, and the coupling capacitor C1. Therefore, the light receiving sensitivity can be adjusted by adjusting the resistance value of the light receiving sensitivity adjusting variable resistor 14.

Next, a case where a beam sensor without sensitivity adjustment is configured will be described.
In the beam sensor, in the manufacturing process, the first switch and the second pin are short-circuited by the short bar of the fourth switch SW4, and the variable sensitivity for light receiving sensitivity adjustment 14 is not connected to the connection terminals P11 and P12. P12 and the external terminals P1 and P2 are in an open state.

  During operation, an H level control signal S1 is supplied to the photodetection IC 20 according to the connection state of the fourth switch SW4, the first switch SW1 is turned on, and the second and third switches SW2 and SW3 are turned off. Accordingly, the voltage signal output from the preamplifier 22 is input to the main amplifier 23 via the first switch SW1 and the coupling capacitor C1 without short-circuiting the external terminals P1 and P2. Therefore, since the wiring length is shorter than when the external terminals P1 and P2 are short-circuited, it is possible to reduce noise from being mixed into the voltage signal transmitted from the preamplifier 22 to the main amplifier 23. Further, since the external terminals P1 and P2 are disconnected by the second and third switches SW2 and SW3, it is possible to reduce mixing of external noise.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The first switch SW1 is connected between the preamplifier 22 which is the first switch portion and the main amplifier 23, and the first switch SW1 is short-circuited or opened depending on the product. Since a variable resistor can be attached to the external terminals P1 and P2 of the photodetection IC 20, it can be used for both a beam sensor with and without a light reception sensitivity adjustment. Further, since the first switch SW1 is turned on in a product without adjusting the light receiving sensitivity, the light receiving signal is output from the preamplifier 22 and then input to the main amplifier 23 via the first switch SW1 and the coupling capacitor C1. The Therefore, since it is not necessary to go through the external terminals P1 and P2 of the photodetection IC 20, the path of the photodetection signal is shortened and the photodetection signal can be transmitted only within the photodetection IC 20, so that noise is mixed in the photodetection signal Can be reduced.

  (2) In the beam sensor without adjusting the light receiving sensitivity, since the second and third switches SW2 and SW3 are turned off, noise is prevented from being mixed into the light receiving signal from the external terminals P1 and P2 of the photodetection IC 20. be able to.

(3) In the beam sensor in which the light receiving sensitivity is not adjusted, parts for short-circuiting the external terminals P1 and P2 of the photodetection IC 20 are not necessary, so that the number of parts can be reduced.
(4) Since the first switch portion is between the preamplifier 22 and the main amplifier 23, the light reception signal level can be amplified by the preamplifier 22 before the light reception signal is transmitted to the outside of the photodetection IC 20, which is caused by noise. The impact can be reduced. Further, since the light reception signal level can be adjusted before being input to the main amplifier 23, the adjustable range can be widened.

In addition, you may implement each said embodiment in the following aspects.
In the above embodiment, the second switch SW2 and the third switch SW3 may be omitted.

In the above embodiment, the beam sensor is not limited to the type that receives reflected light, but may be the type that receives transmitted light.
-Although the said embodiment was actualized in the beam sensor provided with the light projecting element 15 and photodiode PD (light receiving element), the light projection part provided with the light projecting element and the light receiving part provided with the light receiving element were separated. It may be applied to a body sensor system.

In the above embodiment, the control signals S1 for controlling the first to third switches SW1 to SW3 are not the same and may be different.
In the above embodiment, the control signal S1 for controlling the first to third switches SW1 to SW3 may be input from the outside instead of from the printed circuit board.

  In the above embodiment, the first switch SW1 is connected between the preamplifier 22 and the main amplifier 23. However, a switch may be provided in any part of the path from the photodiode PD to the comparator 24. For example, a switch may be provided between the main amplifier 23 and the comparator 24, and an amplifier, a filter, or the like may be connected to the external terminal.

(A) The perspective view which shows the detection sensor of one Embodiment, (b) The block diagram of the detection sensor of one Embodiment. The perspective view of IC for detection sensors of one embodiment. The block diagram of IC for detection sensors of one embodiment. The block diagram of conventional IC for detection sensors.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Beam sensor, 14 ... Variable resistance for light reception sensitivity adjustment, 20 ... Light detection IC, 22 ... Preamplifier, 23 ... Main amplifier, 24 ... Comparator, P1, P2 ... External terminal, PD ... Photodiode, SW1, SW2, SW3, SW4 ... switch.

Claims (7)

A physical quantity detection means for outputting a detection signal of a level corresponding to a physical quantity for detecting the detection object; a determination means for determining the detection object based on the detection signal output from the physical quantity detection means; A detection sensor IC provided with an amplification circuit that amplifies the detection signal output from the physical quantity detection means.
First switch means for short-circuiting or opening a part of a path from the physical quantity detection means to the discrimination means via the amplifier circuit;
A pair of external terminals electrically connected to the first switch portion short-circuited or opened by the first switch means,
The detection sensor IC, wherein the first switch means is switched between short circuit and open by external control. The amplifier circuit is configured to include a preamplifier and a main amplifier,
The detection sensor IC according to claim 1, wherein the first switch portion is between the preamplifier and the main amplifier.   3. A pair of second switch means for short-circuiting or opening between the first switch portion and the pair of external terminals by an operation complementary to the first switch means. IC for detection sensor according to 1. Physical quantity detection means for outputting a detection signal at a level corresponding to a physical quantity for detecting the detected object; and determination means for determining the detected object based on the detection signal output from the physical quantity detection means. A detection sensor comprising:
An amplification circuit for amplifying the detection signal output from the physical quantity detection means; a first switch means for short-circuiting or opening a part of a path from the physical quantity detection means to the discrimination means via the amplification circuit; A detection sensor IC comprising: a pair of external terminals electrically connected to a first switch portion short-circuited or opened by one switch means;
Switching means for switching between short-circuiting and opening of the first switch means;
A detection sensor comprising:   5. The detection sensor according to claim 4, wherein the first switch portion opens the first switch portion, and a detection signal level adjustment unit is connected to the pair of external terminals.   5. The detection sensor according to claim 4, wherein the first switch means short-circuits the first switch part and opens the pair of external terminals.   A pair of second switch means are provided between the first switch portion and the pair of external terminals, and are short-circuited or opened complementarily with the first switch means by the switching means. Item 7. The detection sensor according to any one of Items 4 to 6.

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