JP2766101B2 - Tablet device with display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tablet device with a display having a display function used for a personal computer or a word processor.

[0002]

2. Description of the Related Art Conventionally, as a means for inputting handwritten characters and figures to a personal computer, a word processor, or the like, a tablet device with a display in which a liquid crystal panel 4 and an electromagnetic induction type tablet 3 are overlapped as shown in FIG. Has been put to practical use. This tablet device with display,
Characters and figures input by the detection pen 1 to the electromagnetic induction type tablet 3 are displayed at the position of the detection pen 1 on the liquid crystal panel 4 laminated on the electromagnetic induction type tablet 3, so that it is possible to write on paper with a writing tool. You can type as if you were writing.

Various types of electromagnetic induction type tablets 3 have been proposed. FIG. 15 shows an example.
The detection panel 6 of the electromagnetic induction type tablet 3 is provided with an electrode group arranged in the X and Y directions for detecting the XY coordinates of the detection pen 1. The two electrode groups are formed orthogonally to different planes, respectively, or are formed orthogonally to the same plane when they are formed of insulated coated wires.

The electrodes in the above-mentioned electrode group are arranged in parallel at equal intervals, one end of which is commonly connected,
The other end is connected to one of the analog gate circuits 7 and 8, respectively. That is, each electrode forms a large number of loop groups. The above analog gate circuits 7, 8
Are connected so that the electrode loops are sequentially opened from the end and the voltage between both ends is sent to the A / D converter 9.

A high-frequency current is supplied from a high-frequency power supply 5 to a coil 2 built in the tip of the detection pen 1, and a high-frequency magnetic field generated by the high-frequency current acts on an electrode loop of a detection panel 6 to generate an induced voltage at the electrodes. It happens. This induced voltage is the largest induced voltage generated in the electrode loop immediately below the coil 2, and decreases as the distance from the coil 2 increases. Therefore, if the voltage of each electrode loop is known, the position of the coil 2, that is, the position of the detection pen 1 can be detected.

The analog gate circuits 7 and 8 sequentially take in the voltage of the electrode loop in a time-division manner and send the voltage to the A / D converter 9. The voltage signal input to the A / D converter 9 is converted into a digital signal.
Is calculated.

[0007]

However, the conventional tablet device with a display has the following problems. That is, when detecting the position of the detection pen 1, it is necessary to supply a high-frequency current from the high-frequency power supply 5 to the coil 2 of the detection pen 1 under the control of the coordinate detection circuit 10. And the power consumption by this high frequency current is 1
It reaches as high as 00 mW. The value of the power consumption is relatively large in a device such as a personal computer including a tablet device with a display, and does not cause much problem when commercial power is used. However, in the case of a portable small computer driven by a battery or the like, the amount of power that cannot be ignored is generated.

In order to avoid the above-mentioned problem, a method is usually adopted in which a high-frequency current is applied to the coil 2 only in an input mode for inputting a character or a figure by the detection pen 1 to suppress the power consumption of the battery. As specific means,
A key for instructing the input mode by the detection pen 1 is provided on the keyboard. When the above key is pressed, an input mode is entered, and a high-frequency current is supplied to the coil 2 of the detection pen 1. Then, when the key is pressed again, the input mode ends and the high-frequency current is no longer supplied to the coil 2.

However, in the above-described means, once the key is pressed to indicate the input mode, the high-frequency current continues to flow through the coil 2 until the same key is pressed again to cancel the input mode. Therefore, during the input mode period, a high-frequency current flows through the coil 2 even if the input operation is not actually performed, and there is a problem that the power consumption is not significantly reduced. Further, when the tablet device with the display is left in the input mode due to interruption of another task during the input mode period, it is useless until the operator returns to operate the tablet device with the display again. High frequency current will continue to flow.

As another specific means, a mode switch is provided on the side surface of the detection pen 1 or a micro switch for detecting that the tip of the detection pen 1 is pressed by the liquid crystal panel 4 inside the detection pen 1. Is provided. And
When the mode switch or the micro switch is pressed, an input mode is entered and a high-frequency current is supplied.

FIG. 16 is a diagram showing a detection pen of a tablet device with a display provided with the microswitch and a drive unit thereof. The pen core 11 is movable in the axial direction along the axis of the detection pen 1. Therefore, when the tip of the detection pen 1 is pressed against the surface of the liquid crystal panel, the pen core 11
Is pushed up to turn on the microswitch 12. Then, the input detection circuit 13
Detecting that “2” has been turned “ON”, it sends a detection signal to the control circuit 14 indicating that the detection pen 1 has been pressed against the surface of the liquid crystal panel. Then, the control circuit 14 receives the detection signal from the input detection circuit 13 and outputs a control signal for causing the high-frequency power supply 5 to output a high-frequency current.

On the other hand, when the tip of the detection pen 1 is separated from the surface of the liquid crystal panel, the microswitch 12 is turned off,
The transmission of the detection signal from the input detection circuit 13 to the control circuit 14 is stopped. Then, the output of the control signal from the control circuit 14 to the high-frequency power supply 5 is stopped, and the output of the high-frequency current from the high-frequency power supply 5 to the coil 2 is stopped.

However, in the case of the tablet device with a display provided with the microswitch 12, the start of the detection is slightly delayed in order to detect the input mode when the pen core 11 is pressed against the surface of the liquid crystal panel. Sometimes excessive current flows. Therefore, if you enter characters at high speed,
The four “,” below the characters “dot” and “mu”
However, in the case of a character including a portion where a continuous line segment having a short stroke is continuous as described above, there is a problem that it is difficult to extract the characteristics of the input character and the character is often erroneously recognized. Further, in the case of the tablet device with a display provided with the mode switch, there is a problem that the operation of the mode switch is troublesome, and it can be said that the method is a method in which the operator is ignored.

An object of the present invention is to provide a tablet device with a display which can automatically and accurately supply current to a detection pen only when the detection pen is in the vicinity of a detection panel without burdening an operator. To provide.

[0015]

According to a first aspect of the present invention, there is provided a tablet device with a display, comprising: a detection pen having a coil for generating an AC magnetic field; and a power supply for supplying a current to the coil. A position detection panel for detecting the position of the detection pen by detecting an AC magnetic field generated in the coil by a group of electrodes arranged in parallel in two directions orthogonal to each other, and stacked on the position detection panel, by the detection pen detected position of the detection pen by arrayed plurality of first electrodes and the first electrode to orthogonally parallel arrayed plurality of the position detecting panel having a second electrode a display panel for displaying the indicated position in the display with a tablet having a driving circuit for driving the display panel is sequentially applied voltage to the first electrode and the second electrode An electrode for the first electrode and the second electrode and electrostatically binding of the detection pen tip provided with the display panel, the value of the loaded induced voltage captures induced induced voltage to the electrode The height of the detection pen from the display panel is detected by a predetermined procedure based on the detection pen, and when the height of the detection pen is equal to or less than a predetermined value, a control signal for permitting the output of the power supply is output. A pen position detection circuit for outputting a control signal for stopping the output of the power supply when the power is high is provided.

A tablet device with a display according to a second invention is the tablet device with a display according to the first invention.
The pen position detecting circuit has a voltage comparing means, and compares the induced voltage from the captured electrode of the detecting pen with a reference voltage by the voltage comparing means during a display period of the display panel. If the voltage is equal to or higher than the reference voltage, it is determined that the height of the detection pen is equal to or less than a predetermined value, while if the induced voltage is lower than the reference voltage, it is determined that the height of the detection pen is higher than a predetermined value. It is characterized by doing.

A tablet device with a display according to a third invention is the tablet device with a display according to the second invention.
The pen position detection circuit has a conversion unit for converting the captured induced voltage signal into a DC voltage signal having a peak value proportional to the peak value, and the voltage comparison unit includes a DC voltage signal obtained by the conversion unit. DC voltage comparing means for comparing the peak value of the DC reference voltage with the peak value of the DC reference voltage.

According to a fourth aspect of the present invention, there is provided the tablet device with a display according to any one of the first to third aspects, wherein the electrode provided on the detection pen is cylindrical or substantially conical. And is formed in a non-loop structure so that an induced current does not flow when an AC magnetic field is applied.

According to a fifth aspect of the present invention, there is provided a tablet device with a display according to any one of the first to fourth aspects, wherein a direct current component included in an induced voltage induced in the electrode is removed. And a DC blocking filter for sending the signal to the pen position detection circuit.

A tablet device with a display according to a sixth invention is the tablet device with a display according to the fifth invention, wherein
A pen core urged axially outward such that one end protrudes outward from the tip of the detection pen and movable in the axial direction; and a pen core provided at the other end of the pen core. A switch that is pressed by the other end to be in a conductive state and one terminal of which is connected to the terminal of the electrode at a connection point in the detection pen; and an AC blocking filter that filters a DC component of a voltage signal from the connection point. Through the above switch
With a switch state detection circuit for detecting a pitch on / off, the pen position detection circuit, the detection pen of the display the AC component of the voltage signal from the connection point receives via the DC blocking filter When the height of the detection pen is determined to be equal to or less than a predetermined value by the pen position detection circuit, so as to detect the height from the panel,
Or, the switch by the switch state detection circuit
When the switch is in a conductive state and it is determined that the detection pen is pressed against the display panel, the output of the power supply is permitted.

According to a seventh aspect of the present invention, in the tablet device with a display according to any one of the first to sixth aspects, the pen position detecting circuit should stop outputting the power. The predetermined value of the height of the detection pen at the time of determining that there is a higher than the predetermined value of the height of the detection pen at the time of determining that the output of the power supply should be allowed, It is characterized in that hysteresis is given to the criterion for permitting / stopping the output of the power supply.

According to an eighth aspect of the present invention, in the tablet device with a display according to any one of the first to seventh aspects, the electrodes provided on the detection pen are covered with a dielectric. , Wherein the electrodes are prevented from directly contacting an external object.

According to a ninth aspect of the present invention, there is provided a tablet device with a display according to any one of the first to eighth aspects, wherein the drive circuit is applied between the segment electrode and the common electrode. The display panel includes an alternating circuit for changing a direction of a voltage, and the display panel is a liquid crystal panel that changes a direction of applying a voltage to liquid crystal a plurality of times during a display period of one frame.

[0024]

In the first invention, in order to specify an input location,
A location on the position detection panel is indicated by a detection pen having a coil that generates an alternating magnetic field. Then, the first electrode and the second electrode, which are arranged in parallel in two directions orthogonal to each other, of the display panel stacked on the position detection panel .
The electrode and the electrode provided at the tip of the detection pen are electrostatically coupled.

Then, during the display period in which the position of the detection pen detected by the position detection panel is displayed on the display panel, the first electrode and the first electrode of the display panel are displayed .
When a voltage is sequentially applied to the two electrodes from the drive circuit, the first electrode
A voltage is induced at the electrode of the detection pen based on a change in the voltage applied to the pole and the second electrode . Then, the induced voltage induced on the electrode of the detection pen is taken into the pen position detection circuit.

Then, the height of the detection pen from the display panel is detected by the pen position detection circuit in a predetermined procedure based on the received induced voltage. When the height of the detection pen is equal to or less than a predetermined value, a control signal for permitting output of a power supply for supplying a current to the coil of the detection pen is output to the power supply. On the other hand, if it is higher than the predetermined value, a control signal for stopping the output of the power supply is output.

In this way, during the detection period in which the position of the detection pen is detected by the position detection panel, the height of the detection pen is equal to or less than the predetermined value (that is, the detection pen is located near the surface of the position detection panel). Only in the (input) input mode, current is supplied from the power supply to the electrodes of the detection pen, thereby reducing power consumption.

In the second invention, the voltage comparison means in the pen position detection circuit compares the induced voltage from the electrodes of the detection pen taken during the display period with a reference voltage. If the induced voltage is equal to or higher than the reference voltage, it is determined that the height of the detection pen is equal to or lower than a predetermined value, and a control signal for permitting the output of the power supply is output. On the other hand, if it is lower than the reference voltage, it is determined that the height of the detection pen is higher than a predetermined value, and a control signal for stopping the output of the power supply is output. Thus, the input mode is easily and automatically determined, and the current is supplied to the coil of the detection pen only in the input mode during the detection period.

In the third aspect of the present invention, the converted induced voltage signal is converted into a DC voltage signal having a peak value proportional to the peak value by the converting means in the pen position detecting circuit. Then, the DC voltage comparing means compares the peak value of the DC voltage signal obtained by the converting means with the peak value of the DC reference voltage. If the peak value of the DC voltage signal is equal to or greater than the peak value of the DC reference voltage, it is determined that the height of the detection pen is equal to or less than a predetermined value. On the other hand, when it is lower than the peak value of the DC reference voltage, it is determined that the height of the detection pen is higher than the predetermined value.

In the fourth invention, the electrodes provided on the detection pen are cylindrical or conical and have a non-loop structure. Therefore, even if an AC magnetic field generated on the coil of the detection pen acts, no induced current flows through the electrode. Thus, a stable induced voltage is generated at the electrode.

In the fifth invention, the DC component contained in the induced voltage induced on the electrode of the detection pen is removed by the DC blocking filter and then sent to the pen position detection circuit. Thus, the DC component generated at the electrode due to frictional charging of the detection pen or the like is removed, and erroneous detection of the input mode is prevented.

[0032] In the sixth invention, a direct current indicating on / off of the switch is obtained from a contact in the detection pen to which one terminal of a switch provided in the detection pen is connected to a terminal of the electrode. A voltage signal in which a voltage and an AC induced voltage induced on the electrode are superimposed is output outside the detection pen. The voltage signal from which the AC component has been removed by the AC blocking filter is input to the switch state detection circuit. On the other hand, the voltage signal from which the DC component has been removed by the DC blocking filter is input to the pen position detection circuit.

[0033] Then, by the switch state detection circuit, based on the DC component of the voltage signal, the Sui
Switch on / off is detected. On the other hand, the height of the detection pen from the display panel is detected by the pen position detection circuit based on the AC component of the voltage signal.
When the height of the detection pen is determined to be equal to or less than a predetermined value by the pen position detection circuit, or when the switch is turned on by the switch state detection circuit, the detection pen is pressed against the display panel. If it is determined that the power is output, the output of the power supply is permitted.

In this manner, by superimposing the switch on / off information and the height information of the detection pen into one voltage signal, the number of lead wires from the detection pen to the outside is reduced, and there is an opportunity to pick up noise. It is reduced as much as possible. In addition, reliable determination of the input mode by pressing the detection pen against the display panel and early determination of the input mode by proximity of the detection pen to the display panel are compatible.

In the seventh invention, when the detection pen moves away from the display panel, the height of the detection pen is set to be higher than the predetermined value when it is determined that the output of the power supply should be permitted. When the height of the detection pen reaches the predetermined value, the pen position detection circuit determines that the output of the power supply should be stopped. As a result, even if the detection pen exits the position of the entry height at which the detection pen enters the input mode, it does not immediately enter the non-input mode. In this way, erroneous detection of the position of the detection pen due to frequent repetition of permitting / stopping the output of the power supply when the position of the detection pen is near the entry height is prevented.

According to the eighth aspect of the present invention, even if the tip of the detection pen comes into contact with a human body or the like, since the electrodes are covered with a dielectric, erroneous input to the pen position detection circuit is prevented.

In the ninth invention, the voltage applied to the liquid crystal between the segment electrode and the common electrode in the liquid crystal panel by an alternating circuit provided in a driving circuit of the liquid crystal panel as the display panel. Is changed a plurality of times during the display period of one frame. Each time, the voltage applied to the segment electrode and the common electrode of the liquid crystal panel changes at the same time. As a result, a voltage associated with the change in the voltage of the segment electrode and the common electrode is induced at the electrode of the detection pen.

Thus, the induced voltage used to determine the input mode can be easily obtained by a normal liquid crystal panel display operation.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a basic configuration diagram of the tablet device with display of the present embodiment. This tablet device with display,
The high frequency power supply 27 is connected to the coil 22 built in the detection pen 21.
, A high-frequency magnetic field is generated in the coil 22. The high-frequency magnetic field acts on the electrodes 33, 33,... Of the electromagnetic induction type tablet 25 to generate an induced voltage at the electrode 33. Based on the induced voltage, the detection pen 21
(That is, the input position) is detected. At that time,
The input mode is automatically determined by detecting the height of the detection pen 21 by using the induced voltage from the pen height detection electrode 23 provided at the tip of the detection pen 21, and the coil 22 is controlled only during this input mode. It supplies a high-frequency current.

In FIG. 1, the pen height detecting electrode 23
Has a substantially conical shape and is installed at the tip of the detection pen 21. The output signal from the pen height detection electrode 23 is sent to the pen position detection circuit 26 via the shield wire 28. Here, the input side impedance of the pen height detection electrode 23 needs to be maintained higher than the shield line 28 side impedance. Therefore, if the pen height detecting electrode 23 is connected to an operational amplifier and the operational amplifier is provided in the detecting pen 21, the pen height is input to the pen height detecting electrode 23 with high impedance and the pen position is detected with low impedance. The signal can be transmitted to the circuit 26, and is less likely to be affected by external noise.

However, in this case, it is necessary to provide a power supply for the operational amplifier in the detection pen 21, and the internal structure of the detection pen 21 becomes complicated and the cost increases. Further, in the tablet device with display, since the length of the shield wire 28 may be relatively short, even if the operational amplifier is provided in the detection pen 21 as described above, the effect equivalent to the cost increase can be obtained. Absent. Therefore, in the present embodiment, the operational amplifier 2
9 is provided in the pen position detection circuit 26, and the insertion of a resistor 30 of several hundred ohms into the pen height detection electrode 23 of the shield wire 28 in the detection pen 21 is stopped.

The pen height detecting electrode 2 in the present embodiment
The detection of the height of the detection pen 21 by 3 is performed according to the following principle. That is, as shown in FIG. 1, the tablet unit of the tablet device with a display according to the present embodiment includes a detection panel 25 constituting an electromagnetic induction type tablet for detecting an input position by the detection pen 21, and the above-described electromagnetic induction type tablet. And a liquid crystal panel 24 of a liquid crystal display device that performs display at the input position detected by the above.

As shown in FIGS. 1 and 2, a plurality of common electrodes Y ₁ , Y ₂ ,... Y ₈ (hereinafter, an arbitrary common electrode is described as Y) are arranged in parallel in the liquid crystal panel 24. Transparent substrate 31 and a plurality of segment electrodes X ₁ , X _{2 ,.}
(Hereinafter, an arbitrary segment electrode is referred to as X) and a transparent substrate 32 in which the common electrode Y and the segment electrode X are arranged at predetermined intervals via a spacer or the like so that the common electrode Y and the segment electrode X face each other and are orthogonal to each other. Have been. Liquid crystal is filled between the two transparent substrates.

The common electrodes Y ₁ , Y ₂ ,..., Y ₈ are activated by sequentially receiving the selection pulse of the common electrode drive signal output from the common drive circuit 35. On the other hand, a segment electrode drive signal corresponding to the display data output from the segment drive circuit 36 is input to the segment electrodes X ₁ , X ₂ ,..., X ₄₀ . In this way, a voltage of a predetermined value or more is applied between the activated common electrode Y and the segment electrode X, and the molecular orientation of the liquid crystal at the intersection of the common electrode Y and the segment electrode X changes, and the pixel is displayed. It is done.

The display control circuit 37 outputs the clock signal cp1 and the shift data s to the common drive circuit 35, and sequentially outputs the selection pulse of the common electrode drive signal from each of the output terminals 01 to 08 of the common drive circuit 35. Output.
On the other hand, by incorporating the display data for one row in an internal register and outputs a clock signal cp2 and the display data D ₀ to D ₃ with respect to the segment drive circuit 36 (40 pixels), and further outputs a clock cp1 The segment electrode drive signal corresponding to the latched display data for one row is output to the output terminals 01 to 01.
040.

The power supply circuit 38 includes the common drive circuit 35
A plurality of levels of bias power supplies V _{0 to} V ₅ used for generating the common electrode drive signal and the segment electrode drive signal are supplied to the segment drive circuit 36.

As described above, when each pixel of the liquid crystal panel 24 is displayed under the control of the display control circuit 37, if a direct current is continuously applied to the liquid crystal, the liquid crystal undergoes electrolysis and the performance is reduced. to degrade. Therefore, in order to avoid this, a unique process called liquid crystal display is performed. This process
While maintaining the absolute values of the voltages applied to the common electrodes Y and the segment electrodes X, the direction of application of the voltage applied to the liquid crystal between the two electrodes is changed by one frame based on the alternating signal fr output from the display control circuit 37. This is the process of inverting several tens of times. Hereinafter, this AC conversion processing will be described in more detail.

FIG. 3 is a timing chart of the common electrode drive signals a to h and the segment electrode drive signals. Hereinafter, how the voltage application direction to the liquid crystal changes due to the level inversion of the AC conversion signal fr will be described with reference to FIGS. 2 and 3. When the level of the alternating signal fr is “L”, the selection voltage of the common electrode Y is “V ₀ ”.
And the selection voltage of the common electrode Y is “V ₅ ” when the level of the alternating signal fr is “H”. On the other hand, when the level of the AC signal fr is “L”, the selection voltage of the segment electrode X is “V ₅ ”, and when the level of the AC signal fr is “H”, the selection voltage of the segment electrode X is “V ₀ ”.

Since the pixel at the intersection of the common electrode Y and the segment electrode X to which the selection voltage is applied is displayed, the absolute value of the voltage applied to the liquid crystal of the display pixel is | V ₅ − V ₀ |. In this case, the direction in which the voltage is applied to the liquid crystal is determined by the level of the alternating signal fr. That is, the AC signal fr
Are inverted at times t ₀ , t _3, and t ₆ , the voltages of the common electrode drive signals a to h and the segment electrode drive signal change simultaneously, and the direction of application of the voltage to the liquid crystal is reversed. You do it.

At this time, as shown in FIG. 1, a pen height detecting electrode 23 is provided at the tip of the detecting pen 21 to maintain its input impedance at a high value. Therefore, due to the capacitive coupling between the pen height detecting electrode 23 and the segment electrode X and the common electrode Y of the liquid crystal panel 24 as shown in FIG. 1, the time t ₀ , t ₃ and t ₆ shown in FIG. The spike-like differential wave voltage is applied to the pen height detection electrode 2
Induced to 3.

The peak value of the voltage induced on the pen height detecting electrode 23 is, as shown in FIG.
4 the height of the detection pen 21 regardless of the display content of each pixel
(The distance between the pen height detection electrode 23 and the segment voltage X). Therefore, based on the peak value of the induced voltage generated at the pen height detection electrode 23 at times t ₀ , t ₃ , t ₆ ,... When the image is displayed on the liquid crystal panel 24, the input mode is determined. Can be determined.

That is, in this embodiment, the pen height detecting electrode 23 is detected by the pen position detecting circuit 26.
It is determined whether or not the peak value of the induced voltage induced at the time is higher than the reference value. If it is high, the position of the detection pen 21 is close to the surface of the liquid crystal panel 24, so that it is determined that the input mode is set. Then, a mode signal of level "H" is output. Then, the output switch of the high-frequency power supply 27 is turned on by the mode signal of level “H”,
A high-frequency current is supplied from the high-frequency power supply 27 to the coil 22. On the other hand, when the level of the mode signal becomes “L”, the output switch of the high frequency power supply 27 is turned “off”, and the supply of the high frequency current to the coil 22 is stopped.

As described above, it is possible to determine whether the mode is the input mode or the non-input mode.
When noise enters the electrode 33 of the detection panel 25 and detects the tip position of the detection pen 21 in the non-input mode, the detection can be identified as an erroneous detection. The mode signal may require an analog value or several levels, but usually, binary information of the level “H” and the level “L” is sufficient as described above.

As described above, in this embodiment, the input mode is determined on the basis of the peak value of the spike-like differential wave voltage signal induced on the pen height detection electrode 23. It is difficult to directly compare the peak value of the differential wave voltage with the reference value. Therefore, as will be described in detail below, if the DC voltage is converted into a DC voltage proportional to the peak value of the differential wave voltage signal, the reference voltage can be set at a stable DC voltage, so that a stable comparison can be easily performed. Further, in that case, the comparison circuit for comparing the two can be simplified.

In this embodiment, a circuit as shown in FIG. 5 is used as a pen position detection circuit for converting the differential wave voltage signal input from the detection pen 21 into a DC voltage proportional to the peak value. The pen position detecting circuit 26, the peak value of the positive peak value to a negative peak value can be stored in the capacitor C _2. Therefore, it is optimal for converting a voltage signal having a waveform as shown in FIG. 3 (7) into a DC voltage. The output voltage V ₀ thus output may be compared with a reference voltage by a comparator (not shown). still,
The reset circuit 41 detects the pen height detection electrode 2 in the immediately preceding frame before the start of the display of the display period in each frame.
3 is a circuit for resetting a holding voltage related to the voltage induced in the third voltage. Specifically, a field effect transistor or the like is used.

The capacitor C ₁ provided on the input side
Forms the above-mentioned DC blocking filter, and the pen height detecting electrode 2
3 blocks the direct current component of the induced voltage signal input from 3. This is because when the location of the pen height detection electrode 23 is rubbed against the surface of clothing or the like during the operation of the detection pen 21,
Since the pen height detecting electrode 23 generates a DC voltage by frictional charging and outputs an erroneous mode signal, the pen height detecting electrode 23 is provided to prevent this DC component. Such a DC blocking filter is required even in the pen position detection circuit 26 of another configuration, and the installation location is in the pen position detection circuit 26 or the detection pen 21. Good.

As described above, the tablet device with a display according to the present embodiment has the pen height detecting electrode 23
Is installed. Then, the input impedance of the pen height detection electrode 23 is maintained at a high value, and capacitive coupling is formed with the segment electrode X and the common electrode Y of the liquid crystal panel 24. Thus, the segment electrode X of the liquid crystal panel 24
And a spike-shaped differential wave voltage signal induced on the pen height detection electrode 23 based on a voltage change due to the AC processing of the segment electrode drive signal and the common electrode drive signal applied to the common electrode Y, and a pen position detection circuit. 26 to detect.

The pen position detecting circuit 26 converts the detected differential wave voltage signal from the pen height detecting electrode 23 into a direct current, and the liquid crystal panel 24 of the detecting pen 21 based on the peak value of the differential wave voltage after the direct current conversion. It is determined whether the height from the surface is within a predetermined range. If the height of the detection pen 21 is within the predetermined range, the mode is determined to be the input mode, the level of the mode signal is set to "H", and the output switch of the high-frequency power supply 27 is turned on.

Therefore, according to the present embodiment, the height of the detection pen 21 is detected, and only when the height of the detection pen 21 is below a predetermined value, the coil 2 of the detection pen 21 is automatically detected.
2 can be supplied with a high-frequency current, and power consumption can be reduced.

Hereinafter, another embodiment in which the above-described embodiment is further improved will be described.

<Modified Example of Detecting Pen and Pen Height Detecting Electrode> The DC component blocking means used in the pen position detecting circuit 26 in the above embodiment need not necessarily be formed by circuit elements as shown in FIG. As shown in FIG. 6, a dielectric layer 42 covering the exposed portion of the pen height detection electrode 23 at the tip of the detection pen 21 may be used.

However, when the tip of the detection pen 21 is covered with the dielectric layer 42 as described above, when the detection pen 21 writes characters on the surface of the liquid crystal panel 24 many times, the dielectric layer 4
2 wears out and does not fulfill its purpose as a DC component blocking means. Therefore, as shown in FIG. 7, the pen component 33 formed by a dielectric rod having a rounded tip is inserted through the center of a pen height detecting electrode 44 formed in a substantially conical shape to thereby prevent DC components. Means may be formed. Further, in FIG. 7, the pen height detection electrode 44 is covered with a detection pen outer container 45 made of plastic so as not to be exposed to the outside.

The pen height detection electrode 2 in each of the above embodiments
As shown in FIG. 8A, the reference numerals 3 and 44 are formed so as not to form a complete ring. This is to prevent a loop current from flowing through the pen height detection electrodes 23 and 44 due to the action of the high frequency magnetic field generated by the coil 22 of the detection pen 21 to increase the loss.

As described above, in order to prevent a loop current from flowing through the pen height detection electrode, the pen height detection electrode may be formed as follows. That is,
Fig. 8 (b) shows a structure in which a plate-like electrode is wound in a cylindrical shape while insulating the layers, and Fig. 8 (c) shows a structure in which a linear electrode is wound in a spring shape in which the layers are insulated. Structure.

As described above, various structures can be considered as the structure of the pen height detecting electrode, and as shown in FIG.
The structure in which the pen height detection electrode 23 is covered with the dielectric layer 42 is simple (it only needs to be covered with a resin or glass having a thickness of about 0.2 mm) and extremely effective. In particular, when the tip of the detection pen 21 contacts an operator's finger or the like, erroneous input to the pen position detection circuit 26 due to noise captured by a human body serving as an antenna is significantly reduced.

As in each of the above-described embodiments, a malfunction due to external noise can be prevented by providing the tablet device with display with a DC blocking characteristic. On the other hand, the signal required by the pen position detection circuit 26 to determine the input mode is the same frequency component as the frequency of the AC signal fr (the voltage induced on the pen height detection electrode 23 is the AC signal f
induced synchronously with r). Therefore, by constituting the DC blocking means with a band-pass filter, not only DC components and low frequency components but also high frequency external noise can be blocked.

<Modified Example of Pen Position Detection Circuit> Another embodiment of the pen position detection circuit 26 for converting the differential wave voltage signal input from the detection pen 21 into a DC voltage proportional to its peak value is as follows. There is such a circuit. In this circuit, approximately one frame is integrated after rectifying the differential wave voltage induced in the pen height detecting electrode 23.
In most cases, the alternating signal fr during the display period is inverted every time 13 common electrodes Y are selected. Therefore, for example, when the number of the common electrodes Y is 400, the number of inversions of the level of the alternating signal fr during display of one screen is 400/13 ≒ 30. The level of the mode signal can be determined based on the integrated value of the 30 pulses.

FIG. 9 is a timing chart of signals in each section of this embodiment. 9 (a) shows the waveform of the AC signal fr, FIG. 9 (b) shows the waveform of the sampling signal rising when the level of the AC signal fr changes, and FIG. 9 (c) shows the waveform synchronized with the AC signal fr. FIG. 9D shows the waveform of the differential wave voltage signal induced in the detection electrode 23, and FIG. 9D shows the waveform of the differential wave voltage signal shown in FIG. 9C. FIG. 9 (e) shows the waveform of a signal that has been subjected to double-wave rectification after passing through an analog gate circuit as a gate signal.
5 is a waveform of a signal obtained by integrating the rectified signal shown in FIG.

Incidentally, the sampling signal shown in FIG. 9 (b) has a considerably wide pulse width for easy understanding. Actually, the pulse width of the differential wave voltage signal waveform may be about the same as the pulse width of the AC signal fr, and may be 1/10 or less of the pulse width of the AC signal fr. The differential wave voltage signal shown in FIG. 9C includes noise (portions (a), (b), (c), and (d) in the figure).

Here, as described above, since the sampling signal having a pulse width of about the pulse width of the differential voltage signal waveform is used as the gate signal of the analog gate circuit, pulses other than the pulses in the differential voltage signal are used. The noise waveform existing at the point is removed. In this manner, the integrated value I _{30 of 30} pulses for one frame in the waveform after the double-wave rectification from which the component due to the external noise has been removed.
Get. Then, the obtained noise-free integral value I ₃₀
By comparing with the reference voltage, it can be easily determined whether or not the input mode is set.

In the above embodiment, the pen height detecting electrode 2
Differentiating the differential wave voltage signal from FIG. 3 (FIG. 9 (c)) to further narrow the pulse width and, at the same time, narrowing the pulse width of the sampling signal (FIG. 9 (b)) further enhances the noise removal effect. be able to.

According to each of the above embodiments, the liquid crystal panel 24
It is possible to automatically determine whether or not the input mode is set for each one frame scanning period in or for a shorter time. By the way, the detection pen 21
When the user enters a thinking state while holding the input mode near the boundary of the input mode determination area, the input mode and the non-input mode
One mode repeats in a short time. Therefore, in this state, if the output / stop of the high-frequency current to the coil 22 of the detection pen 21 is switched in a short time in accordance with the mode signal output from the pen position detection circuit 26, a malfunction occurs due to a transient phenomenon at the time of output / stop of the high-frequency current. May be.

The following embodiment is an embodiment in which a malfunction due to the repetition of the output / stop of the high-frequency current as described above is prevented. In this embodiment, the tablet device with the present display (hereinafter, referred to as the tablet device) according to the comparison result of the peak voltage of the differential wave voltage signal from the pen height detection electrode 23 or the integrated value of the peak voltage for one frame and the reference voltage. When this device is simply set to the input mode state, the device is not immediately set to the non-input mode state even if the next comparison result is the non-input mode. Then, the comparison determination is further performed a plurality of times, or the comparison determination is performed again after a predetermined time has elapsed.
As a result, when it is continuously determined that the apparatus is in the non-input mode, the apparatus is set to the non-input mode state.

FIG. 10 is a timing chart of each signal in this embodiment. FIG. 10A is a signal obtained by converting the differential wave voltage signal from the pen height detection electrode 23 into a direct current by rectification or the like, and shows that the detection pen 21 repeatedly enters and leaves the input mode with high frequency. Represents. FIG. 10B is a signal obtained by binarizing the signal of FIG. 10A with a reference voltage to be compared. FIG. 10 (c) is a diagram of FIG.
This is a mode signal output as a result of the input mode determination based on the value signal. This input mode signal has the level of the binarized signal “L” even if the elapsed time “t _d ” has elapsed since the level of the binarized signal shown in FIG. In this case, the level becomes "L" for the first time, and the state is set to the non-input mode state.

Further, in another embodiment for preventing a malfunction due to the repetition of the output / stop of the high-frequency current, a plurality of reference voltages used in the comparison judgment are set. FIG. 11 is a circuit diagram of the comparison and judgment circuit in the present embodiment. This circuit is based on the operational amplifier 4
The comparison value of the comparator using No. 6 is provided with hysteresis. At this time, since the comparator using the operational amplifier 46 has no hysteresis characteristics, the comparison value is given hysteresis by using the zener diode 47 together.

When the voltage of the input signal to the pen position detecting circuit 26 changes from low to high by providing the comparison value of the comparator with hysteresis as described above (non-input mode → input mode). Can be made different from the reference voltage in the case where the reference voltage changes from higher to lower (input mode → non-input mode). That is, a plurality of reference voltages can be set.

FIG. 12 is a timing chart of each signal when the pen position is detected by the comparison and judgment circuit shown in FIG. FIG. 12 (a) shows a DC signal of the differential wave voltage signal from the pen height detecting electrode 23.
_U "and" E _L "is a different reference voltages. FIG. 12 (b) Voltage""is the mode signal when a reference voltage, the reference voltage" E _L level in E _L "or more sections has to "H". On the other hand, FIG. 12 (c) a mode signal when a reference voltage a voltage "E _U", the level at the reference voltage "E _U" or more sections becomes the "H" In each case, it is determined whether or not the input mode is set based on one reference voltage.
When the differential wave voltage rises and falls near the reference voltage (FIG. 12)
In (e) and (f) of (a), the mode signal repeats "H" and "L" accordingly.

FIG. 12D shows a case where the reference voltage is given a hysteresis, that is, the comparison voltage when the voltage changes from low to high is “E _U ”, while the comparison voltage is high to low. This is a mode signal in the case where the comparison voltage when changing is “ _EL ”. Considering this in terms of the position of the detection pen 21, if the detection pen 21 approaches the surface of the liquid crystal panel 24 from a distance, it will not enter the input mode unless it is quite close, but once it enters the input mode, it enters the input mode. This means that the input mode is maintained until the user further moves away from the position where the input mode is moved, and it is difficult to change to the non-input mode.

This means that after the position of the detection pen 21 reaches a predetermined position and enters the input mode once, the operator holds the detection pen 21 near the predetermined position and enters a thinking state. ), As shown in (e) and (f), even if the voltage rises or falls near the reference voltage “E _U ” or “E _L ”, the level of the mode signal is changed until the detection pen 21 is securely separated. H "or" L "is maintained.

In this embodiment, by giving the reference voltage a hysteresis as described above, it is possible to prevent malfunction due to repeated output / stop of the high-frequency current.

FIG. 13 shows a pen position detecting circuit system in an improved example of the conventional display-equipped tablet device having the above-described microswitch. The pen core 51 is, for example, a shaft rod formed of an insulating material such as Teflon, and is urged outward in the axial direction so that one end thereof protrudes from the tip of the detection pen 21 and is movable in the axial direction. ing. And
When the tip of the detection pen 21 is pressed against the surface of the liquid crystal panel 24, the pen core 51 is pushed up and the micro switch 52 is turned on. The lead from the pen height detection electrode 44 is connected to the lead from one terminal of the microswitch 52 in the detection pen 21. Then, a DC voltage of + V volt is applied to one common lead wire drawn out of the detection pen 21 from the connection point via a resistor R. Further, the pen position detecting circuit 26 is connected to the common lead via a high-pass filter 53 serving as the DC blocking filter, and is connected to the switch state detecting circuit via a low-pass filter 54 serving as the AC blocking filter. A certain pen contact detection circuit 55 is connected. On the other hand, the micro switch 5
The other terminal of 2 is grounded.

Therefore, when the micro switch 52 is "OFF", the DC voltage "+"
V is applied with a voltage obtained by superimposing the differential wave voltage induced on the pen height detection electrode 44. The DC voltage "V" is 5 volts in this embodiment, and the pen height detection electrode The peak value of the differential wave voltage signal induced at 23 is about 100 mV even when the tip of the detection pen 21 contacts the surface of the liquid crystal panel 24.

As a result, the DC component is cut by the high-pass filter 53 to the pen position detection circuit 26, and a spike-like differential wave voltage corresponding to the distance between the detection pen 21 and the surface of the liquid crystal panel 24 is applied. , Detection pen 2
1 outputs a mode signal corresponding to the degree of approach.

At the same time, the pen contact detection circuit 55
When the spike-like differential wave component is cut by the low-pass filter 54 and the detection pen 21 contacts the surface of the liquid crystal panel 24 to turn on the microswitch 52, a voltage of “0” V is applied. When the detection pen 21 is separated from the surface of the liquid crystal panel 24 and the microswitch 52 is turned off, a voltage of "5" V is applied. Therefore, the pen contact detection circuit 55 outputs a mode signal corresponding to the contact / non-contact of the detection pen 21.

The two mode signals from the pen position detection circuit 26 and the pen contact detection circuit 55 are input to the OR element 56, and the output switch 57 of the high frequency power supply 27 is operated by the output signal from the OR element 56. That is, if the level of either the mode signal from the pen position detection circuit 26 or the mode signal from the pen contact detection circuit 55 is “H”, in other words, the detection pen 21 approaches the surface of the liquid crystal panel 24. When the contact is made, the high frequency current is supplied to the coil 22.

As described above, in this embodiment, since the number of lead wires from the detection pen 21 to the pen position detection circuit 26 is reduced, there is an effect that external noise is hardly picked up. Further, the detection pen 21 is connected to the liquid crystal panel 2.
Since the input mode is determined by the pen position detection circuit 26 before touching the touch panel 4, the delay in the start of detection in a conventional tablet device with a display having a microswitch as shown in FIG. 16 can be improved. That is, both the reliable determination of the input mode by pressing the detection pen 21 against the liquid crystal panel 24 and the early determination of the input mode by the proximity of the detection pen 21 to the liquid crystal panel 24 can be achieved.

In each of the above embodiments, the case where the liquid crystal panel 24 is used as a display panel constituting the display-equipped tablet device is described as an example. However, the present invention is not limited to this. For example, an electroluminescence panel may be used. In short, any display panel may be used as long as a voltage for display is applied to the electrodes of the display panel during display. The specific circuit of the pen position detection circuit in each of the above embodiments is not limited to the disclosed circuit diagram.

[0088]

As is clear from the above, the tablet device with a display of the first invention is provided with an electrode at the tip of a detection pen having a coil for generating an AC magnetic field, and is provided with a first electrode and a first electrode of the display panel . Based on the induced voltage induced on the second electrode in response to a change in the voltage applied from the drive circuit, the pen position detection circuit determines the height of the detection pen from the display panel in a predetermined procedure. If the height of the detection pen is less than a predetermined value, the output of the power supply that supplies current to the coil of the detection pen is permitted, while if the height of the detection pen is higher than a predetermined value, Since the output of the power supply is stopped, only when the detection pen is located at a position close to the surface of the display panel (in other words, when the detection pen is located near the detection panel stacked on the display panel), the power supply is stopped. Above Current is supplied to the coil from. Therefore, according to the present invention, the current is automatically and accurately supplied to the detection pen only when the detection pen is in the vicinity of the detection panel to reduce the power consumption without burdening the operator. You can do it.

In the tablet device with a display according to the second aspect of the present invention, the voltage comparing means in the pen position detecting circuit compares the induced voltage induced on the electrode of the detecting pen with a reference voltage, and the induced voltage is calculated as follows. If the voltage is equal to or higher than the reference voltage, the height of the detection pen is determined to be equal to or less than the predetermined value.If the height is lower than the reference voltage, the height of the detection pen is determined to be higher than the predetermined value. The input mode is determined, and the current can be supplied to the coil of the detection pen only in the input mode.

Further, in the tablet device with a display according to the third invention, the pen position detecting circuit has a converting means and a DC voltage comparing means, and the converting means converts an induced voltage signal from the electrode of the detecting pen into a signal. Converted to a DC voltage signal having a peak value proportional to the peak value, by the DC voltage comparing means, by comparing the peak value of the DC voltage signal obtained by the converting means and the peak value of the DC reference voltage, Since the height of the detection pen is detected based on the comparison result, the input mode can be determined easily and stably based on the DC voltage signal and the DC reference voltage.

In the tablet device with display of the fourth invention, the electrodes provided on the detection pen are formed in a cylindrical or substantially conical shape and have a non-loop structure. When the generated AC magnetic field acts, no induced current flows through the electrodes. Therefore, a stable induced voltage is induced in the electrode, and the height of the detection pen can be stably detected based on the stable induced voltage.

The tablet device with a display according to the fifth aspect of the present invention is arranged such that a DC component included in an induced voltage induced on an electrode of the detection pen is removed by a DC blocking filter and then sent to the pen position detection circuit. Because it was
DC components generated at the electrodes due to frictional charging or the like of the detection pen can be removed. Therefore, erroneous detection of the height of the detection pen from the display panel due to frictional charging or the like can be prevented.

Further, in the tablet device with a display according to the sixth invention, when the detection pen is pressed against the display panel, one terminal of the switch which is pressed by the pen core and conducts is connected to the electrode of the detection pen and the detection pen. connected by the connection point of the inner, the switch by the switch state detection circuit which receives via an AC blocking filter the DC component of the voltage signal from the connection point
Detects the switch on / off, since so as to detect the height of the display panel of the detection pen by the pen position detecting circuit an AC component received via the DC blocking filter from the connection point, Based on one voltage signal in which the switch on / off information and the height information of the detection pen are superimposed, it is possible to detect the pressure contact and the proximity of the detection pen to the display panel. Therefore, the number of lead wires from the detection pen to the outside can be reduced, and the chance of picking up external noise can be reduced.

Further, the accurate determination of the input mode by pressing the detection pen against the display panel and the early determination of the input mode by the proximity of the detection pen to the display panel can be performed more accurately. Current can be supplied to the coil of the detection pen only in the input mode.

Further, in the tablet device with a display according to the seventh invention, the output of the power supply should be permitted by the predetermined value of the height of the detection pen when it is determined that the output of the power supply should be stopped. The height of the detection pen at the time of determination is higher than the predetermined value, and the reference for permitting / stopping the output of the power supply has a hysteresis. The pen does not immediately enter the non-input mode when the pen exits the position at the entry height. Therefore, even if the position of the detection pen is in the vicinity of the entry height, frequent repetition of permission / stop of the output of the power supply can be prevented, which is caused by frequent repetition of permission / stop of the output of the power supply. Erroneous detection of the position of the detection pen can be prevented.

In the tablet device with a display according to the eighth aspect of the present invention, the electrodes provided on the detection pen are coated with a dielectric so that the electrodes do not directly contact an external object. Erroneous input to the pen position detection circuit can be prevented even when the tip contacts a human body or the like.

Further, in the tablet device with display of the ninth aspect, the direction of the voltage applied between the segment electrode and the common electrode is changed by the AC conversion circuit provided in the drive circuit during the display period of one frame. Since the display panel is configured with a liquid crystal panel that is changed a plurality of times, the electrodes of the detection pen are applied to the electrodes of the detection pen based on a periodic voltage change of the segment voltage and the common voltage in a normal liquid crystal panel display operation. An induced voltage can be induced. Therefore, an induced voltage for input mode determination can be easily generated.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an embodiment of a display-equipped tablet device of the present invention.

FIG. 2 is a block diagram of the liquid crystal panel and its driving unit in FIG.

FIG. 3 is a timing chart of a common electrode drive signal and a segment electrode drive signal in FIG. 2;

FIG. 4 is a diagram showing a relationship between a peak value of an induced voltage generated at a pen height detection electrode in FIG. 1 and a height of a detection pen.

FIG. 5 is a diagram showing a specific example of a pen position detection circuit in FIG. 1;

FIG. 6 is a configuration diagram of a detection pen different from FIG.

FIG. 7 is a configuration diagram of a detection pen different from FIGS. 1 and 6;

FIG. 8 is a diagram showing a specific example of a pen height detection electrode.

FIG. 9 is a timing chart of each signal in an embodiment in which an input mode is determined based on an integrated signal obtained by integrating a differential wave voltage signal from a pen height detection electrode.

FIG. 10 is a timing chart of each signal in an embodiment in which a non-input mode is determined based on two determination results.

FIG. 11 is a diagram showing a specific example of a comparison determination circuit in which a reference voltage has hysteresis.

FIG. 12 is a timing chart of each signal in an embodiment in which a reference voltage has hysteresis.

FIG. 13 is a diagram showing a pen position detection circuit diameter in an embodiment having a microswitch in which the number of lead wires from the detection pen is reduced.

FIG. 14 is a configuration diagram of a conventional tablet device with a display.

FIG. 15 is a block diagram of the electromagnetic induction type tablet and its driving unit in FIG. 14;

FIG. 16 is a diagram showing the diameter of a conventional pen position detection circuit provided with a microswitch.

[Description of Signs] 21: detection pen, 22: coil,
23, 44: Pen height detection electrode, 24: Liquid crystal panel, 25: Detection panel, 26: Pen position detection circuit, 27: High frequency power supply, 42 ...
Dielectric layer, 43, 51 ... pen core, 52
... Micro switch, 53 ... High-pass filter,
54: low-pass filter, 55: pen contact detection circuit, X: segment electrode, Y: common electrode.

Claims (9)

(57) [Claims] 1. A detecting pen having a coil for generating an AC magnetic field, a power supply for supplying a current to the coil, and an AC magnetic field generated in the coil by a group of electrodes arranged in parallel to two directions orthogonal to each other. A position detection panel for detecting the position of the detection pen by detecting the position of the detection pen, a plurality of first electrodes stacked on the position detection panel and arranged in parallel, and arranged in parallel and orthogonal to the first electrodes. a display panel of the position of the detection pen detected by the position sensing panel displays the location indicated by the detection pen having a plurality of second electrodes, the first electrode and
A display-equipped tablet having a drive circuit for driving the display panel by sequentially applying a voltage to the second electrode, wherein the display-equipped tablet is provided at a tip end of the detection pen.
An electrode that is electrostatically coupled to the first electrode and the second electrode, and an induced voltage induced in the electrode is captured, and a predetermined procedure is performed on the display panel of the detection pen based on the value of the captured induced voltage. In order to stop the output of the power supply when the height of the detection pen is lower than a predetermined value, a control signal for permitting the output of the power supply is output. A tablet device with a display, comprising: a pen position detecting circuit for outputting a control signal for the display. 2. The display-equipped tablet device according to claim 1, wherein the pen position detection circuit has a voltage comparison means, and detects a voltage from the captured electrode of the detection pen during a display period of the display panel. The induced voltage and the reference voltage are compared by the voltage comparing means. When the induced voltage is equal to or higher than the reference voltage, the height of the detection pen is determined to be equal to or less than a predetermined value, while the induced voltage is higher than the reference voltage. A tablet device with a display, wherein when it is low, it is determined that the height of the detection pen is higher than a predetermined value. 3. The tablet device with a display according to claim 2, wherein the pen position detecting circuit is configured to convert the induced voltage signal into a DC voltage signal having a peak value proportional to the peak value. The tablet device with a display, wherein the voltage comparing means is a DC voltage comparing means for comparing the peak value of the DC voltage signal obtained by the converting means with the peak value of the DC reference voltage. 4. The tablet device with a display according to claim 1, wherein the electrode provided on the detection pen has a cylindrical or substantially conical shape, and an AC magnetic field acts on the electrode. A tablet device with a display, wherein the tablet device is formed in a non-loop structure so that an induced current does not flow in a case where the display is performed. 5. The tablet device with a display according to claim 1, wherein a direct current component included in an induced voltage induced in said electrode is removed and sent to said pen position detecting circuit. A tablet device with a display, comprising a blocking filter. 6. The tablet device with a display according to claim 5, wherein the pen core is urged axially outward such that one end protrudes from a tip of the detection pen to the outside, and is movable in the axial direction. Is provided at the other end of the pen core, is pressed by the other end of the pen core to be in a conductive state, and one terminal thereof is connected to a terminal of the electrode at a connection point in the detection pen. and in which the switch receives via an AC blocking filter the DC component of the voltage signal from the connection point, provided with a switch state detecting circuit for detecting the on / off the switch, the pen position detection circuit, the An AC component of a voltage signal from a connection point is received through the DC blocking filter, and the height of the detection pen from the display panel is detected. If the height of the serial detection pen is determined to be equal to or less than a predetermined value, or the switch is the detection pen in the conductive state is determined to be in pressure contact with the display panel by the switch state detection circuit A display device with a display, wherein the output of the power supply is permitted in such a case. 7. The tablet device with a display according to claim 1, wherein the pen position detection circuit detects the position of the detection pen when determining that the output of the power supply should be stopped. When determining that the predetermined value of the height is to permit the output of the power supply, the height of the detection pen is set to be higher than the predetermined value, and a criterion for permitting / stopping the output of the power supply is set. A tablet device with a display, characterized in that the tablet device has hysteresis. 8. The tablet device with a display according to claim 1, wherein the electrode provided on the detection pen is covered with a dielectric, and the electrode does not directly contact an external object. A tablet device with a display, characterized in that: 9. The tablet device with a display according to claim 1, wherein the driving circuit is configured to change the direction of a voltage applied between the segment electrode and the common electrode. A tablet device with a display, comprising a circuit, wherein the display panel is a liquid crystal panel that changes the direction of applying voltage to the liquid crystal a plurality of times during a display period of one frame.