JP2011022839A - Touch switch - Google Patents

Abstract

[PROBLEMS] To realize a touch switch on glass without attaching a sensor such as a touch switch material, light, or ultrasonic wave outside the case.
In a touch switch provided in a sealed case, a disk-shaped glass disposed on a surface of the sealed case, and at least two disposed at a predetermined distance around the glass disk. A plurality of ultrasonic transmission / reception sensors, transmission means for alternately transmitting the ultrasonic transmission / reception sensors, and distance calculation means for calculating the distance to the glass end face by receiving the ultrasonic waves reflected by the end face of the glass. In addition, one end of the ultrasonic wave transmission / reception sensor is in close contact with the glass surface and is disposed at a predetermined angle with respect to the glass surface, and the ultrasonic reflector is brought into contact with an arbitrary portion of the glass surface. In some cases, the position of the arbitrary portion is calculated.
[Selection] Figure 1

Description

  The present invention relates to a touch switch that can be used even on a glass surface in a sealed case as used in a field instrument, and relates to a touch switch that identifies a touch position using ultrasonic waves.

  The case of the field instrument employs a sealed container for the reasons of dust proof, explosion proof, waterproof and moisture proof. In such a case, a non-contact switch is configured as a display setting device using an infrared reflection SW, a magnetic detection method, or the like.

FIG. 8 is a main part configuration diagram showing a conventional example of an infrared touch switch used for switching between display mode and setting mode of a field device and changing internal data.
In FIG. 8, reference numeral 1 denotes an infrared light emitting unit disposed in a field device (not shown). A drive circuit including a rectangular wave generating unit 2 causes a rectangular wave drive current IF to flow through the light emitting element 3 to emit infrared light. .

  Reference numeral 4 denotes a light receiving element that receives the light emitted from the light emitting element 3 and reflected by the reflector 9. Reference numeral 10 denotes a front surface of the field device, which is a transparent member (glass) disposed between the light emitting element 3 and the light receiving element 4 and the reflector 9.

  Reference numeral 5 denotes a variable resistor having one end connected to the emitter terminal of the light receiving element 4 and the other end grounded. A comparator 6 has a non-inverting input terminal side connected to the emitter terminal of the light receiving element 4, and a determination voltage 7 set to a predetermined voltage is applied to the inverting input terminal side. The output terminal of the comparator 6 is connected to the determination circuit 8.

  In the above-described configuration, when there is no reflector 9, the light receiving element 4 cannot receive infrared rays, so that the photocurrent IL does not flow. Although not shown in the drawing, there is a shield between the light emitting element 3 and the light receiving element 4, and the light receiving element 4 is configured not to directly receive the light emitted from the light emitting element 3.

When there is the reflector 9, infrared light is reflected by the reflector 9 and a photocurrent IL flows through the light receiving element 4.
This photocurrent IL is converted into a voltage VL by the variable resistor 5 and input to the comparator 6.
The comparator 6 outputs a signal indicating whether VL is larger or smaller than the determination voltage 7 to the determination circuit 8. Based on this signal, the determination circuit 8 determines the presence or absence of the reflector 9 (switch ON / OFF).

Japanese Patent Laid-Open No. 2008-216075 JP 2005-092527 A JP-A-11-327772

However, in the infrared SW, the place where the structure can be placed is limited, and the number of SWs is also limited.
Therefore, although it is desired to employ a touch switch (for example, a sensitive resistance type touch switch), it is necessary to affix it outside the glass surface, and the electrode portion is also exposed to the outside. In that case, there is a problem that the chemical resistance is difficult, and there is also a problem in dustproof, explosion-proof, waterproof, moisture-proof and the like.
Therefore, an object of the present invention is to realize a touch switch on glass without attaching a touch switch material or a sensor such as light or ultrasonic wave outside the case.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In the touch switch provided in the sealed case, the disk-shaped glass disposed on the surface of the sealed case and at least two ultrasonic waves disposed at a predetermined distance around the glass disk A transmission / reception sensor; transmission means for alternately transmitting the ultrasonic transmission / reception sensor; and distance calculation means for calculating a distance to the glass end surface by receiving ultrasonic waves reflected by the end surface of the glass. One end of the transmission / reception sensor is in close contact with the glass surface and disposed at a predetermined angle with respect to the glass surface, and when the ultrasonic reflector is brought into contact with an arbitrary portion of the glass surface, The present invention is characterized in that the position of an arbitrary location is calculated.

The invention described in claim 2 is the touch switch according to claim 1,
The other end of the ultrasonic wave transmitting / receiving sensor is formed of an elastic body.

The invention according to claim 3 is the touch switch according to claim 1,
A thermometer is arranged in the sealed case.

The present invention has the following effects.
According to claim 1, in the touch switch provided in the sealed case, the disk-shaped glass disposed on the surface of the sealed case and the periphery of the glass disk are disposed at a predetermined distance. Further, at least two ultrasonic wave transmitting / receiving sensors, transmitting means for alternately transmitting the ultrasonic wave transmitting / receiving sensors, and distance calculation for calculating the distance to the glass end surface by receiving ultrasonic waves reflected by the end surface of the glass Means, and one end of the ultrasonic transmission / reception sensor is disposed in close contact with the glass surface and at a predetermined angle with respect to the glass surface, and the ultrasonic reflector is disposed at an arbitrary position on the glass surface. Since it is configured to calculate the position of the arbitrary position when it is brought into contact with the touch panel, it is not necessary to attach a touch panel material or a sensor such as light or ultrasonic wave to the outside of the case. Can be realized switch, it can be transmitted without attenuation ultrasound.

  According to the second aspect, since the other end of the ultrasonic transmission / reception sensor is formed of an elastic body, excess vibration can be removed.

  According to the third aspect, since the thermometer is disposed in the sealed case, it is possible to perform accurate calculation by correcting the shift of the touch position based on the temperature fluctuation.

It is AA sectional drawing of the top view (a) and (a) figure which shows an example of embodiment of this invention. It is the top view (a) and side view (b) which show the detail of an ultrasonic wave transmission / reception sensor. It is a circuit block diagram of the touch switch of the present invention. It is a figure which shows a specific drive waveform. It is a figure which shows the state which the ultrasonic wave has transmitted the inside of a glass disc. It is a schematic diagram in the case of performing spatial orientation measurement. It is a top view which shows the example which attached the ultrasonic transmission / reception sensor facing four. It is a principal part block diagram which shows the prior art example of an infrared touch switch.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1A is a plan view of a touch switch showing an example of an embodiment of the present invention, and FIG.
In these drawings, reference numeral 1 denotes a disk-shaped glass, and its peripheral portion is airtightly fixed to a recess formed in the inner periphery of the cover 4 by an O-ring (not shown) or the like. A case 5 is airtightly fixed to the cover 4.

  Reference numeral 6 denotes a rectangular (or circle) circuit unit, and a display 8 is attached to the upper surface thereof with a predetermined space. Reference numerals 2 and 3 denote ultrasonic transmission / reception sensors. In the example of this figure, the ultrasonic sensor is disposed at a predetermined distance from the edge of the circuit unit 6 formed in a circle or rectangle, and one end is fixed by the fixing unit 7. ing. The other ends of the ultrasonic transmission / reception sensors 2 and 3 are attached in close contact with the glass 1. Reference numeral 9 denotes a temperature sensor provided in the fixed unit 7.

FIG. 2 is a plan view (a) and a front view (b) showing the details of the ultrasonic transmission / reception sensors 2 and 3 formed in, for example, a cylindrical shape. In these figures, reference numeral 10 denotes an ultrasonic oscillator, which is composed of a piezoelectric vibrator (crystal, PZT, piezoelectric ceramic, etc.).
11 is a wedge formed of a resin or the like, and is formed to a length that does not apply excessive pressure to the contact with the glass 1 in a state where the touch panel is assembled.

  These ultrasonic transmission elements 2 and 3 have a predetermined angle (θ) and are fixed to the fixed unit 7, and both end surfaces are formed in parallel, and one end has a surface with respect to the surface of the glass 1. The ultrasonic waves can be transmitted without being attenuated by being formed so as to be in close contact with each other. Reference numeral 12 denotes a dumper having a horizontal portion, and the other end of the ultrasonic transmission element is fixed in close contact with the horizontal portion. The dump 12 is formed of an elastic body and has a function of removing excess vibration from the vibrator (ultrasonic oscillator 10) (not transmitting vibration to the circuit board 6).

  FIG. 3 is a circuit block diagram. In FIG. 3, reference numerals 2 and 3 denote ultrasonic transmission / reception sensors (sensors 1 and 2). Reference numerals 25 and 26 denote switches, 21 denotes a processor, 22 denotes a clock generation circuit, 23 denotes a timing generation circuit, 24 denotes a transmission drive circuit, 27 denotes an amplifier, 28 denotes an antialiasing filter, and 29 denotes an A / D converter.

  In the above configuration, the processor 21 and the A / D converter 29 are synchronized by the clock generator circuit 22, and the switch 25 and the switch 26 are switched by the processor 21. Further, a trigger signal is given from the processor 21 to the timing generation circuit 23.

  A drive waveform is transmitted from the timing generation circuit 23 to the transmission drive circuit 24, and the sensors 1 and 2 are driven via the switches 25 and 26. The sensors 1 and 2 function as a reception sensor at the same time as driving, and a received waveform is digitally converted by an A / D converter 29 via an amplifier 27 and an anti-aliasing filter 28 and read into the processor 21.

Next, the operation will be described.
FIG. 4A and FIG. 4B are diagrams showing specific drive waveforms.
The driving frequency is, for example, 1 MHz in the ultrasonic frequency band. As shown in FIG. 4A, driving is performed alternately between the sensor 1 and the sensor 2.

  The ultrasonic signal oscillated from the sensor 1 or 2 enters the glass through the surface of the glass 1 because one surface is in contact with the surface of the glass 1. The sensor 1 or 2 is disposed at an angle θ with respect to the vertical direction (see FIG. 2). When the ultrasonic signal is incident on the surface of the glass 1 with a predetermined angle, the ultrasonic wave is sequentially reflected and transmitted at the same angle on both surfaces of the glass 1 as shown in FIG. .

  In practice, the angle of refraction changes according to Snell's law, but is omitted in FIG. Here, it is assumed that most of the ultrasonic waves are reflected as they are at the interface between the surface of the glass 1 and the air. When the ultrasonic wave reaches the end face of glass (the place indicated by 16 in FIG. 5), it is reflected and returned. (See FIG. 5 (b))

  FIG. 5B shows a reflected back wave (without finger contact). Actually, the end face has a circular shape in the case of the glass of FIG. 1, and such reflected back waves return to multiple.

  FIG. 5C shows the state of ultrasonic transmission when a finger is present. When the touch switch is touched with a finger, the finger is made of a solid or liquid, so that ultrasonic waves are reflected on the bone and skin surface of the finger. Since the shape of the finger is close to a circular structure, the reflection condition of the ultrasonic wave changes at the place where the finger touches compared to when the finger is not present. That is, as shown in FIG. 5C, a reflected back wave (indicated by a dotted line a) is generated (actually a slightly more complicated waveform).

  Since the transmission speed of the ultrasonic wave is determined by the substance and temperature, the position can be identified by measuring the arrival time of the reflected wave. The speed of sound can be corrected by measuring the temperature with a thermometer 9 (see FIG. 1).

  As described above, the actual ultrasonic reflected waveform is a more complicated waveform because the reflected wave returns from all the end faces of the glass. For example, one method for identifying when a finger is touched is as follows.

  First, an ultrasonic reflection signal is always read into the processor 21 in a state where there is no finger contact. The read signal is stored in the processor 21. In order to deal with disturbances, the waveform data of each time may be subjected to an integration averaging process.

  The processor 21 performs correlation comparison between the waveform data stored when the finger is not touching and the waveform data captured every time thereafter. If the correlation value is high, it is determined that there is no finger contact. When the correlation value is low, it is determined that there is a high possibility that the finger has touched.

Again, the correlation value is calculated at the next timing, and if the correlation value with the waveform data that has been determined to be highly likely to have touched the finger last time is high, it can be identified that the finger has touched that position.
In the above description, spatial orientation cannot be measured, but the position can be identified by arranging the ultrasonic transmission / reception sensor 3 in addition to the ultrasonic transmission / reception sensor 2.

FIG. 6 is a schematic diagram when spatial orientation measurement is performed. That is, the distance L1 (radius of the circle 31) is identified from the ultrasonic transmission / reception sensor 2 and the distance L2 (radius of the circle 32) is identified from the ultrasonic transmission / reception sensor 3, and the position is extracted from the position by the principle of triangulation. The processor 21 calculates the spatial position.
FIG. 7 shows an example in which four ultrasonic wave transmission / reception sensors (2, 3, 41, 42) are mounted on the circuit unit 6 so as to face each other, and the contact position can be determined more precisely.

According to the above-described configuration, the position of the glass surface can be calculated by using the two ultrasonic transmission / reception sensors and using the fact that the reflected wave changes due to the finger contact.
In addition, this sensor is arranged inside the case and is not affected by the outside (such as atmosphere).

The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention. For example, the contact object to the glass disk may be a pen-shaped object with a rounded tip, and in short, any object having a different reflected waveform of ultrasonic waves when touched may be used.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

DESCRIPTION OF SYMBOLS 1 Glass 2,3 Ultrasonic transmission / reception sensor 4 Cover 6 Circuit unit 7 Fixed unit 8 Display 9 Temperature sensor 10 Ultrasonic transmission / reception element

Claims (3)

  In the touch switch provided in the sealed case, the disk-shaped glass disposed on the surface of the sealed case and at least two ultrasonic waves disposed at a predetermined distance around the glass disk A transmission / reception sensor; transmission means for alternately transmitting the ultrasonic transmission / reception sensor; and distance calculation means for calculating a distance to the glass end surface by receiving ultrasonic waves reflected by the end surface of the glass. One end of the transmission / reception sensor is in close contact with the glass surface and disposed at a predetermined angle with respect to the glass surface, and when the ultrasonic reflector is brought into contact with an arbitrary portion of the glass surface, A touch switch configured to calculate the position of an arbitrary location.   The touch switch according to claim 1 or 2, wherein the other end of the ultrasonic wave transmitting / receiving sensor is formed of an elastic body.   The touch switch according to claim 1, wherein a thermometer is disposed in the sealed case.

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