JP2001124594A - Display device of detection switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of obviously grasping an operating state on this kind of a detection switch. SOLUTION: The display device sets a threshold value between a background level and an operation level, and is applied to the detection switch generating switching output on the basis of the comparison of a detection value and the threshold value. The display device is provided with a zero resetting reference value storing means for storing the detection value obtained at a time point as a zero resetting reference value in response to prescribed operation, a zero resetting reference subtraction means for subtracting the zero resetting reference value from the detection value, and a display control means for displaying the detection value subtracting the zero resetting reference value from the zero resetting reference subtraction means on a display. The arbitrary detection value can be displayed by an absolute value making the background level as a reference by storing the detection value corresponding to the background level in the prescribed operation as the zero resetting reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric switch,
The present invention relates to a display device suitable for various detection switches such as a proximity switch and an ultrasonic switch, and particularly relates to a characteristic amount (for example, a transmitted light amount or a reflected light amount, a reflected ultrasonic intensity, a capacitance, an inductive capacitance) which is correlated with a detection target. And the like, and a display device of a detection switch in which a detection value, a threshold value for switching processing, and the like can be visually recognized through a display device.

[0002]

2. Description of the Related Art A display device of this type detects the presence and liquid level of an object using a detection medium such as light, a magnetic field, an electric field, and an ultrasonic wave, such as a photoelectric switch, a proximity switch, and an ultrasonic switch. Widely applied to the detection switch.

[0003] The threshold value for switching determination in these detection switches is between a detection value corresponding to a background level where no detection target object or the like exists and a detection value corresponding to an operation level where the detection target object or the like exists. Is set automatically or manually. Then, in the operation mode, the switching output is generated based on the comparison between the detected value at each time and the threshold value.

A display device provided in a detection switch displays a detected value and / or a threshold value on a predetermined display in a digital or analog manner in an operation mode. Based on this display, the user can grasp the operation state of the detection switch (whether it is a background state or an operation state).

[0005]

However, such a conventional display device for a detection switch merely displays the detected value on the display as it is, and thus does not know the detected values of the background state and the operating state. It is difficult for a person to intuitively judge the operation state of the detection switch just by looking at the display.

In addition, in the case of a detection switch such as a fiber type photoelectric switch (commonly referred to as a fiber amplifier) which can be arranged closely in a large number via a DIN rail, a detection value corresponding to a background level and an operation level correspond to the detection level. Since the detected value has a unique value for each photoelectric switch, the display value may differ between the detection switches in the same background state, which makes it more difficult to determine the operation state.

The present invention has been made in view of such a conventional problem.
It is an object of the present invention to provide a display device that allows the operating state of this type of detection switch to be grasped at a glance.

Another object of the present invention is to provide DI
Provided is a display device that allows the operation state of each detection switch to be grasped at a glance even in the case of a detection switch such as a fiber type photoelectric switch that can be arranged closely in a large number through an N-rail. It is in.

Another object of the present invention is to provide a display device capable of accurately grasping a relative relationship between a background level and a threshold level.

It is still another object of the present invention to provide a display device which does not give a user a sense of discomfort due to a display mode in which the detected value is lower than the background level.

[0011]

A display device of a detection switch according to the present invention sets a threshold value between a background level and an operation level, and compares a detected value with a threshold value in an operation mode. Is a display device that is applied to a detection switch that generates a switching output based on the information.

Here, the "background level" means a detection value obtained in a state where no detection target object or the like exists.

The "operation level" means a detected value in a state where an object to be detected or the like is present.

The "detected value" means a detected value of a characteristic amount (for example, a transmitted light amount or a reflected light amount, a reflected ultrasonic intensity, a capacitance, an induction capacitance, etc.) correlated with the detection target. are doing.

Further, the "threshold value" means a threshold value for judging the above-mentioned switching of the characteristic amount.

This display device includes a zero reset reference value storage means, a zero reset reference value subtraction means, and a display control means.

The zero reset reference value storage means has a function of storing a detected value obtained at that time as a zero reset reference value in response to a predetermined operation.

Here, the "predetermined operation" includes various operations for generating a timing signal for designating a storage timing, such as a pressing operation of a push button switch.

The zero reset reference value subtracting means has a function of subtracting the zero reset reference value from the detected value.

The display control means has a function of displaying on the display the detected value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means.

Here, the “display” includes both a digital display such as a 7-segment display and an analog display such as a bar graph display.

The display device stores a detected value corresponding to the background level as a zero reset reference value by a predetermined operation, so that an arbitrary detected value can be displayed as a relative value based on the background level. It is composed of

According to such a configuration, when the detected value is at the background level, the display content of the display becomes zero or a value close thereto. On the other hand, when the detected value is at the operation level, the display content of the display becomes a considerably large value. Therefore, according to such a display mode, the operation state of this type of detection switch can be grasped at a glance.

In a preferred embodiment of the above-mentioned display device, the zero reset reference value subtracting means further has a function of subtracting the zero reset reference value from the threshold value.

In addition, the display control means includes a detection value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means and / or a threshold value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means. Is displayed on the display.

By storing a detected value corresponding to the background level as a zero reset reference value by a predetermined operation, an arbitrary detected value and / or a threshold value is displayed as a relative value based on the background level. Configured to obtain.

Here, "and / or" means that only the detected value is displayed, only the threshold is displayed, and both the detected value and the threshold are displayed. are doing.

According to such a configuration, the relative relationship between the background level and the threshold level can be accurately grasped.

In still another preferred embodiment of the display device described above, the display control means sets the display to zero when the polarity of the detected value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means is negative. It is configured to display.

According to such a configuration, the user does not feel uncomfortable due to a display mode in which the detected value is lower than the background level.

In still another preferred embodiment of the above-described display device, the threshold value is automatically set by teaching at least a detected value corresponding to a background level.

Here, "at least from the teaching of the detected value corresponding to the background level" includes a case where the threshold value is set in the middle (1/2) between the background level and the operation level.

According to such a configuration, the threshold value automatically set without the user's awareness can be accurately recognized as a relative value to the background level.

[0034] In still another preferred embodiment of the above-described display device, the detection switch has a main body housing that can be juxtaposed via a DIN rail, and a detection head that is separated from the main body housing. An indicator for selectively displaying the detected value and the threshold value is provided on the surface of the housing.

According to such a configuration, even in the case of a detection switch such as a fiber type photoelectric switch which can be closely arranged and arranged via a DIN rail, the operation state of each detection switch can be grasped at a glance. It is possible to do.

The display device of the photoelectric switch of the present invention has a DI
It has a main body housing that can be juxtaposed via an N-rail, and a detection head connected to the main body housing by a reciprocating optical fiber. An indicator and operation keys are provided on the surface of the main body housing.

Further, in the main body housing, there are provided photoelectric detection means, switching means, zero reset reference value storage means, zero reset reference value subtraction means, and display control means.

The photoelectric detecting means has a function of detecting the amount of light that has been emitted from the distal end of the outward fiber and returned to the proximal end of the return fiber via the object detection area.

Here, the "photoelectric detecting means" includes various semiconductor light receiving elements and an amplifier for amplifying the light receiving output.

The switching means has a function of comparing the detection value of the photoelectric detection means with a threshold to generate a switching output.

Here, the "switching means" includes a hardware type such as an analog comparator and a software type performed by a microcomputer program.

The zero reset reference value storage means has a function of storing, as a zero reset reference value, a detection value of the photoelectric detection means obtained at that time in response to a predetermined operation of the operation key.

The zero reset reference value subtracting means has a function of subtracting the zero reset reference value from the detected value.

The display control means displays on the display the detected value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means.

By storing a detected value corresponding to the background level as a zero reset reference value by a predetermined operation, an arbitrary detected value can be displayed as a relative value based on the background level.

In a preferred embodiment of the present invention, the zero reset reference value subtracting means further has a function of subtracting the zero reset reference value from the threshold value.

The display control means may include a detection value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means and / or a threshold value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means. Has the function of displaying

By storing a detected value corresponding to the background level as a zero reset reference value by a predetermined operation, an arbitrary detected value and / or a threshold value is displayed as a relative value based on the background level. Configured to obtain.

In still another preferred embodiment of the present invention, the display control means displays zero on the display when the polarity of the detected value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means is negative. Has functions.

In still another embodiment of the present invention, the display is a digital display.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a display device for a detection switch according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a state in which multiple photoelectric switches to which the display device of the present invention is applied are closely mounted.

As shown in the figure, in this example, n photoelectric switches composed of units U1 to Un are DIN
The rails 5 are mounted in close contact with each other. Each detection switch has a main body housing 1 that can be juxtaposed via a DIN rail 5, and detection heads 7a and 7b connected to the main body housing 1 by reciprocating optical fibers 4a and 4b. Although the detection heads 7a and 7b are schematically illustrated in the figure for convenience of description, various specific structures of the heads are known.

On the front surface (back surface) of the main body housing 1, a display unit 3 and an operation unit 2 are provided. In this example,
As the display 3, a 4-digit 7-segment display is employed. The operation unit 2 includes a plurality of push-button switches functioning as function keys, increment keys, and the like.

The outer shape of the main body housing 1 has a height H,
It is designed in a thin rectangular parallelepiped shape having a length L and a thickness D. The electric cord 6 pulled out of the main housing 1 is for extracting a switching signal.

A circuit device mainly composed of a microcomputer is built in the main body housing 1. FIG. 2 shows the electrical hardware configuration of this circuit device.

As shown in FIG.
It comprises a microcomputer 8 for controlling the whole detection switch, a light emitting system hardware circuit 9, a light receiving system hardware circuit 10, and an output system hardware circuit 11.

The light emission hardware circuit 9 includes a pulse light emission control circuit 9a for generating a pulse signal under the control of the microcomputer 8, a drive circuit 9b for amplifying a pulse output from the pulse light emission control circuit, and a drive circuit 9b. And a light emitting element 9c driven by a pulse signal from Then, the pulse light obtained from the light emitting element 9c is introduced into the outward optical fiber 4a described above,
The light is emitted from the tip head section 7a to the object detection area 13.

The light-receiving system hardware circuit 10 is emitted from the head section 7a of the forward fiber, then is introduced into the return fiber 4b from the head section 7b via the object detection area 13, and is supplied to the base end of the fiber 4b. A light receiving element 10a for receiving the light returned to the light receiving element, an amplifier 10b for amplifying an output pulse of the light receiving element 10a, and an A / D converter 10c for converting the pulse amplified by the amplifier 10b to a digital signal. . The received light amount data converted into a digital signal by the A / D converter 10c is taken into the microcomputer 8.

As will be described in detail later, in the microcomputer 8, a switching output is generated based on a comparison between the detected value and the threshold value. This switching output is amplified by a drive circuit 11a constituting an output hardware circuit 11, and then drives an open collector type output transistor 11b.

The switching output signal obtained in this manner is taken out through the electric cord 6 drawn out of the main body housing 1 as described above.

The microcomputer 8 contains various system programs for realizing the function of the detection switch. These system programs include a process in the threshold teaching mode and a process in the operation mode.

The configuration of the process in the threshold value teaching mode is shown in the flowchart of FIG. 3, and the procedure of the threshold value teaching operation is shown in the explanatory diagram of FIG.

As shown in FIG. 4, the procedure of the threshold value teaching operation is as follows. First, as shown in FIG. Then, as shown in FIG. 4B, in a state where the detection target object 12 is present in the object detection area 13, the reflection light amount from the detection object is measured.

That is, in FIG. 3, when the processing is started, first, the apparatus enters a state of waiting for a background light quantity sample instruction (NO in steps 301 and 302).

In this state, if a pressing operation of a specific key constituting the operation unit 2 is performed, the result of reading the key operation (step 301), it is determined that there is a background light quantity sample instruction (step 302 YES), Immediately received light amount (received data from A / D converter 10c)
Is stored as the background level LB. Subsequently, the apparatus enters a state of waiting for a light quantity sample instruction when an object is present (steps 304 and 305 NO).

In this state, when a predetermined push-button key constituting the operation unit 2 is operated, the result of reading the key operation (step 304), it is determined that there is a light quantity sample instruction when an object is present (step 305 YES). Subsequently, the amount of received light (light reception data from the A / D converter 10c) at that time is stored as the operation level LD (step 360).

Thereafter, the background level LB obtained above is obtained.
Further, a threshold value LT is obtained based on the operation level LD (step 307). In this example, the threshold LT
Is in the middle of the background level LB and the operation level LD (1 /
Set to 2).

The configuration of the process in the operation mode is shown in the flowcharts of FIGS.

In the flowchart of FIG. 5, when the process is started by turning on the power, an initialization process is first performed to read the zero reset reference value (Z) and initialize various data (step 501). . At this time, it is assumed that the value of the zero reset reference value (Z) is the initial value (0).

Subsequently, the presence or absence of a zero reset input is determined by checking the contents of a predetermined zero reset flag (step 502).

Here, if there is no zero reset input (NO in step 502), a light emitting / receiving process is performed and a light receiving amount (V) is obtained (step 504). Here, as described above, the light emitting / receiving process is to send a pulse light toward the object detection area 13, receive the reflected light, and receive the received light amount data taken in from the A / D converter 10c. This is stored as the amount of received light (V).

Thereafter, the display mode is determined (step 505). This mode switching is performed in advance by a predetermined key operation on the operation unit 2.

Here, if it is determined that the mode is the light amount display mode, that is, the mode in which the detected value at that time is displayed on the display 3 (step 505 YES), a light amount display value calculation process is performed (step 506). In this light amount display value calculation process (step 506), a process of subtracting the zero reset reference value (Z) read out in step 501 from the received light amount (V) obtained in step 504 is performed. At this time, since the value of the zero reset reference value (Z) is still zero, the calculated light amount display value is the detection value itself at that time.

Thereafter, a light quantity display process is executed based on the calculated light quantity display value (step 507).

FIG. 6 shows the details of the light quantity display processing (step 507).

As shown in the figure, in the light quantity display processing, first, it is determined whether the polarity of the light quantity display value is positive or negative (step 601). Here, if the polarity of the light quantity display value is determined to be positive, the light quantity display value is displayed on the display 3 as it is (step 602). On the other hand, if the polarity of the light quantity display value is determined to be negative, zero is displayed instead of the light quantity display value at that time (step 60).
3).

As a result of the execution of the light amount display processing, as will be described later in detail, a display with a sense of incongruity that the detection level is lower than the background level is not performed.

Returning to the flowchart of FIG. 5, when the display mode is determined to be the threshold display mode (step 50).
(5NO) Subsequently, a threshold display value calculation process is executed (step 508), and a process of subtracting the zero reset reference value (Z) from the previously obtained threshold level (LT) is executed. Also at this time, the zero reset reference value (Z)
Is zero. Therefore, the threshold (LT) is displayed on the display 3 as it is.

Thereafter, threshold value display processing (step 50)
9) is executed, and the obtained threshold display value is displayed on the display 3 as it is.

Thereafter, an ON / OFF determination process for generating a switching output is executed (step 51).
0). In the ON / OFF determination process (step 510), a switching output is generated based on a comparison between the detected light amount (V) and the threshold value (LT).

As described above, immediately after the power is turned on, in a state where there is no zero reset input yet, the received light amount (V) and the threshold value (LT), which are the detected values, are displayed as absolute values on the display 3. You.

On the other hand, when zero reset is instructed by a predetermined key operation on the operation unit 2 (step 502 YES), a process of changing the zero reset reference value (0) is executed (step 503). Is stored as the zero reset reference value (Z).

As a preferable operation procedure, this zero reset operation is performed at the time of measuring the amount of background reflected light as shown in FIG. As a result, by performing a predetermined operation for zero reset, the background level (LB)
Is stored as the zero reset reference value (Z).

After the zero reset operation is performed in this manner, any detected value is displayed as a relative value based on the background level, and the threshold value is also displayed as a relative value based on the background level. You.

That is, similarly to the above, after the light emission / reception processing (step 504) is performed, if it is determined that the display mode is the light amount value display (step 505YE).
S), a light amount display value calculation process is executed (step 50).
6).

This light quantity display value calculation processing (step 50)
In 6), the result of subtracting the zero reset reference value (Z) from the received light amount (V) at that time (step 506), and then, when the light amount display processing (step 507) is executed, the display 3 displays The received light amount (V), which is the detected value at that time, is displayed as a relative value based on the background level (LB).

Similarly, when the display mode is determined to be the threshold display mode (step 505 NO), the threshold display value calculation processing is executed (step 508).
The zero reset reference value (Z) is subtracted from the threshold data (LT) at that time. The zero reset reference value (Z) at this time is a value corresponding to the background level (LB).

Therefore, when the threshold value display processing (step 509) is executed thereafter, the threshold value (LT) is displayed on the display 3 as a relative value based on the background level (LB). .

When the zero reset operation is performed (YES in step 502), a zero reset reference value (Z) change process is performed (step 503), and the value of the zero reset reference value (Z) is set to the background level (Z). As a result, the zero reset reference value (Z) corresponding to the background level (LB) is subtracted from the received light amount (V) by executing the light amount display value calculation process (step 506). Threshold display value calculation processing (step 508)
From the threshold data (LT), the background level (L
The zero reset reference value (Z) corresponding to B) is subtracted. As a result, by executing the light amount display process (step 507) or the threshold value display process (step 509), the display unit 3 displays, as a relative value based on the background level, the amount of received light or the threshold corresponding to the detected value. The values are displayed selectively.

Next, specific examples of display modes before and after the zero reset operation are shown in FIG.
This will be described with reference to FIGS.

Assume that each unit U shown in FIG.
Background level (LB), threshold level (LT), operation level (L) for 1, U2, U3, U4, U5 to Un
It is assumed that the value of D) is in the state shown in the table of FIG. That is, each unit U1, U2, U3, U4, U
The values of the background level (LB), threshold level (LT), and operation level (LD) of U5 to U6 to Un are U1 (200
0,3500,5000), U2 (3000,450)
0,6000), U3 (1000, 2000, 300
0), U4 (5000, 6000, 7000), U5
(1000, 2000, 3000), U6 (3000,
4500,6000), ~ Un (1000,3000,
5000).

Each unit (U1, U2, U3, U4, U
FIG. 8 is a bar graph showing the values of the background level (LB), the threshold level (LT), and the operation level (LD) of (5, U6 to Un). As is clear from the figure, the detected light amount ranges and values of the respective units vary considerably.

FIG. 9 shows a display form when the detected values are displayed on the display unit 3 on the premise of the states shown in FIGS. Note that, in the drawing, it is assumed that the switching outputs of the units U5 and Un are in the ON state, and the switching outputs of the other units are in the OFF state.

As shown in the figure, in this state, the display value of each unit is U1 (2000), U2 (300)
0), U3 (1000), U4 (5000), U5 (3
000), U6 (3000) to Un (5000). Therefore, it is difficult to immediately determine which unit is in the background state and which unit is in operation by just looking at these numbers. In particular, as is apparent from U5 and U6, the numerical display is the same regardless of whether one is in the ON state and the other is in the OFF state.

On the other hand, in the case of the display mode after executing the zero reset process of the present invention, as shown in FIG. 10, the display content of each unit is U1 (000).
0), U2 (0000), U3 (0000), U4 (0
000), U5 (2000), U6 (0000)-Un
(4000). The point to note here is O
Except for the units U5 and Un in the N state, all the other units U1, U2, U3, U4 and U6 are (00
00). Therefore, the operation state of the switch can be grasped at a glance based on whether the displayed content is 0000 or a considerably large value exceeding 1000.

In the above example, in order to facilitate understanding, the units U1, U2, U3, U
For all 4, U6, 0000 is displayed,
Actually, not only 0 but also a small numerical value of about 100 or less will appear, but in any case, the displayed numerical value is much smaller than the operating state level of 1000 or 4000 or the like. Therefore, even in that case, it should be easy to determine whether the operation state of each unit is the background detection state or the object detection state.

As is apparent from the above description, according to this embodiment, in the state of measuring the amount of background reflected light shown in FIG. 4A, if a predetermined key operation is performed on the operation unit 2 shown in FIG. In the flowchart of FIG. 5, it is determined that there is a zero reset input (step 502).
YES), a zero reset reference value (Z) change process is performed (step 503). In this process (step 503), the received light amount (V) corresponding to the background level (LB) is stored as it is as the zero reset reference value (Z).

Therefore, in the light quantity display value calculation processing (step 506), the detection value corresponding to the background level, which is the zero reset reference value (Z), is subtracted from the received light quantity (V), which is the detection value at that time. When the light amount display processing (step 507) is executed, the display 3 displays
The received light amount (V), which is the detection value at that time, is the background level (L
It is displayed as a relative value based on B).

Similarly, in the threshold display value calculation processing (step 508), the zero reset reference value (Z) is calculated from the threshold data (LT) previously set in step (307) of the flowchart of FIG. Will be deducted. Therefore, when the threshold display process (step 509) is executed, the threshold is displayed on the display 3 with a relative value based on the background level (LB).

In addition, even if the detected value at that time becomes lower than the background level due to some disturbance or other environmental change in the object detection area, it can be seen from FIG.
As a result, the display on the display 3 does not become negative.

However, when the transmission type is used, the light quantity display value is always displayed as it is without making the determination in step 601. In the case of the transmission type, the background level (L
B) corresponds to the amount of received light when there is no light-blocking object, and the operation level corresponds to the amount of received light when there is a light-blocking object. At the background level, the display is almost zero, and at the operation level, a negative value is displayed. A switch provided on the operation unit 2 is designated to determine whether to perform the reflection type processing or the transmission type processing.

Therefore, according to this embodiment, as is apparent from a comparison between FIGS. 9 and 10, even a large number of fiber-type photoelectric switches which can be closely arranged and arranged via a DIN rail. In addition, an unsightly state in which different values are displayed for each unit is eliminated, and the operation state of each detection switch can be grasped at a glance.

[0104]

As is apparent from the above description, according to the present invention, the operation state of this type of detection switch can be grasped at a glance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which multiple photoelectric switches are closely mounted.

FIG. 2 is a block diagram schematically showing a hardware configuration of a single photoelectric switch.

FIG. 3 is a flowchart illustrating a process in a threshold value teaching mode.

FIG. 4 is an explanatory diagram of a threshold value teaching operation.

FIG. 5 is a flowchart illustrating processing in an operation mode.

FIG. 6 is a flowchart illustrating details of a light amount display process.

FIG. 7 is a table showing the background, threshold value, and operation level of each unit;

FIG. 8 is a diagram showing a comparison of detection ranges of respective units.

FIG. 9 is a diagram showing a display mode before a zero reset.

FIG. 10 is a diagram showing a display form after zero reset.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body housing 2 Operation part 3 Display 4a Outbound optical fiber 4b Inbound optical fiber 5 DIN rail 6 Electric code 7a, 7b Detection head 8 Microcomputer 9 Light emitting system hardware circuit 10 Light receiving system hardware circuit 11 Output system hardware circuit 9a Pulse emission control circuit 9b Drive circuit 9c Light emitting element 10a Light receiving element 10b Amplifier 10c A / D converter 11a Drive circuit 11b Open collector type output transistor U1-Un unit LB Background level LT Threshold level LD Operating level 12 Object to be detected 13 Object detection area H Height of main body housing L Length of main body housing D Width of main body housing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Inoue O-Muron Co., Ltd. (10) Hanazono Todo-cho, Ukyo-ku, Kyoto-shi (72) Inventor Takashi Kamei O-Muron, 10-Hanazono Todo-cho, Ukyo-ku, Kyoto, Kyoto Co., Ltd. F term (reference) 2F041 DA05 DB03 DB05 5G055 AA15 AB08 AE28

Claims (9)

[Claims] The present invention is applied to a detection switch which sets a threshold value between a background level and an operation level and generates a switching output based on a comparison between a detection value and a threshold value in an operation mode. A display device, comprising: a zero reset reference value storage means for storing a detected value obtained at that time as a zero reset reference value in response to a predetermined operation; and a zero reset reference for subtracting the zero reset reference value from the detected value. Value subtraction means, and display control means for displaying on a display a detection value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means, and the detection value corresponding to the background level is reduced to zero by a predetermined operation. Table of detection switches configured so that any detected value can be displayed as a relative value based on the background level by storing it as a reset reference value. Apparatus. 2. The zero reset reference value subtracting means further has a function of subtracting the zero reset reference value from the threshold value, and the display control means subtracts the zero reset reference value by the zero reset reference value subtraction means. Detection value, and / or
By having a function of displaying on a display a threshold value from which the zero reset reference value has been subtracted by the zero reset reference value subtracting means, by storing a detected value corresponding to a background level as a zero reset reference value by a predetermined operation, The display device of a detection switch according to claim 1, wherein an arbitrary detection value and / or a threshold value can be displayed as a relative value based on a background level. 3. The detection according to claim 1, wherein the display control means displays zero on the display when the polarity of the detection value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means is negative. Switch display device. 4. The method according to claim 1, wherein the threshold value is automatically set by teaching a detection value corresponding to at least a background level.
3. The display device of the detection switch according to any one of 3. 5. A detection switch has a main body housing that can be juxtaposed via a DIN rail, and a detection head separated from the main body housing, and a detection value and a threshold value are provided on a surface of the main body housing. The display device for a detection switch according to any one of claims 1 to 4, further comprising a display for selectively displaying the display. 6. A main body housing that can be juxtaposed via a DIN rail, and a detection head connected to the main body housing by a reciprocating optical fiber, and a display and operation keys are provided on a surface of the main body housing. The main body housing includes photoelectric detection means for detecting the amount of light emitted from the forward fiber tip and returned to the proximal end of the return fiber via the object detection area and the photoelectric detection means. A switching means for generating a switching output by comparing a detection value of the means with a threshold value, and storing a detection value of the photoelectric detection means obtained at that time as a zero reset reference value in response to a predetermined operation of the operation key. Zero reset reference value storage means, zero reset reference value subtraction means for subtracting the zero reset reference value from the detected value, and zero reset reference value subtraction means. Display control means for displaying on the display a detected value from which the zero reset reference value has been subtracted by the step, and storing the detected value corresponding to the background level as a zero reset reference value by a predetermined operation. The display device of the photoelectric switch is configured to be able to display the detected value of as a relative value based on the background level. 7. The zero reset reference value subtracting means further has a function of subtracting the zero reset reference value from the threshold value, and the display control means subtracts the zero reset reference value by the zero reset reference value subtraction means. Detection value, and / or
It has a function of displaying a threshold value from which the zero reset reference value has been subtracted by the zero reset reference value subtraction means, and stores a detection value corresponding to a background level as a zero reset reference value by a predetermined operation, thereby enabling arbitrary detection. 7. The display device of the photoelectric switch according to claim 6, wherein the value and / or the threshold value can be displayed as a relative value based on a background level. 8. The photoelectric conversion device according to claim 6, wherein the display control means displays zero on the display when the polarity of the detection value from which the zero reset reference value is subtracted by the zero reset reference value subtraction means is negative. Switch display device. 9. The display device for a photoelectric switch according to claim 6, wherein the display is a digital display.