JP2006065815A - Input / output integrated display device - Google Patents

Abstract

Interference noise to reception ultrasonic waves of a reception unit, even if the space of a housing in which a drive circuit for a backlight light source is housed and the space of a housing in which a reception unit is housed are continuous or shared. An input / output integrated display device that does not easily generate ultrasonic waves is realized.
In a digitizer device 1, an inverter 22c for lighting a lamp 22b made of a cold cathode tube is an inverter using a winding coil.
[Selection] Figure 1

Description

  The present invention relates to an input / output integrated display device using an ultrasonic digitizer.

  Recently, a thin and light input / output integrated display device using a liquid crystal display has been developed. Generally, an input method that occupies the majority includes both a resistive film method and an electromagnetic induction method.

  The resistive film type digitizer is as follows. Two films coated with a transparent conductive film are bonded to the surface of the display so as to maintain a certain gap. When the transparent conductive film is pressed by the pen and brought into contact with the upper and lower sides, a resistance change of the transparent conductive film as seen from the periphery of the film occurs. Then, by detecting this resistance change, the position coordinates are calculated and displayed on the display.

  An electromagnetic induction type digitizer is one in which a pattern film of a coil is arranged on the back of a display, the position coordinates of the pen are calculated by detecting a change in the electromagnetic field, and the position of the pen is displayed on the display.

  In both cases, since a film and its holding or shielding mechanism are provided on the front or back surface of the display, there is a problem that the input / output integrated display device is not thin and light.

  However, as the demand for further thinning and lightening increases, the ultrasonic method has recently begun to attract attention as a digitizer method.

  An ultrasonic digitizer does not place any film on the front or back side, but instead, by placing multiple ultrasonic receiving elements around the display, it transmits from the pen's ultrasonic transmitting element. In this method, the received ultrasonic waves are measured, the ultrasonic waves are measured, the position coordinates are calculated by three-point surveying, and what is input with the pen is output to the display. This basic concept and details are described in Patent Document 1.

  The principle of a general ultrasonic pen input digitizer will be briefly described with reference to FIGS. FIGS. 2 and 4 are plan views of FIG. 1 showing a digitizer device (input / output integrated display display device) 1 of the present invention, which will be described later. explain. As shown in FIG. 2, the ultrasonic digitizer device 1 includes a liquid crystal display 2, a receiving unit 3, and a pen 4. The liquid crystal display 2 includes a liquid crystal panel 21 and a backlight 22, and the liquid crystal panel 21 receives light from the backlight 22 and performs display. In addition, the liquid crystal panel 21 receives an input by pressing from the pen 4. The backlight 22 turns on the lamp 22b by the inverter 22c, and irradiates the liquid crystal panel 21 with uniform light through the light guide plate 22a. The receiving unit 3 can receive signals from the pen 4 with one infrared receiving element 31 and two ultrasonic receiving elements 32 and 33. The pen 4 can transmit infrared rays from the infrared transmission element 41 and ultrasonic waves from the ultrasonic transmission element 42. FIG. 3 shows an example of the signal transmission timing employed for calculating the pen input position as the reception timing.

  When the pen 4 in FIG. 2 contacts the screen of the liquid crystal panel 21 and a switch inside the pen (not shown) is turned on, infrared light and ultrasonic waves are transmitted from the pen 4 at the same time. Thereafter, since the infrared ray transmitted from the pen 4 is the speed of light, the infrared receiving element of the receiving unit 3 has a timing that is sufficiently early to be negligible compared to the speed of the ultrasonic wave that is the speed of sound, that is, at the same time as the switch is turned on. Reach 31. Eventually, as shown in FIG. 4, the ultrasonic waves are detected by the respective receiving elements by moving the distance to the ultrasonic receiving elements 32 and 33 at the speed of sound. At this time, the arrival time difference t1 to the ultrasonic reception element 32 and the arrival time difference t2 to the ultrasonic reception element 33 with respect to the arrival time of the infrared rays to the infrared reception element 31 vary depending on the position of the pen 4.

From the values of the arrival time difference and the sound speed, the distance L1 (distance between the ultrasonic transmission element 42 and the ultrasonic reception element 32) and L2 (the ultrasonic transmission element 42 and the ultrasonic reception element 33) shown in FIG. Further, since the distance L0 between the ultrasonic receiving element 32 and the ultrasonic receiving element 33 is originally determined, the coordinate (X, Y) of the pen is an arithmetic circuit such as a microcomputer. The drawing calculated and adjusted to overlap the pen tip is displayed on the liquid crystal panel 21.
US Pat. No. 4,814,552

  However, in an input / output integrated liquid crystal display device using an ultrasonic digitizer and a backlight using a lamp, a significant performance degradation due to noise to the ultrasonic digitizer occurs due to the following reasons.

  When the light source of the backlight of the liquid crystal display is a discharge lamp such as a cold cathode tube and the boosting element of the inverter for lighting the lamp is a piezoelectric element, the lamp is driven by electric energy → mechanical energy → electric energy conversion. It will be. Accordingly, in the piezoelectric type inverter circuit, since the element mechanically vibrates at the time of boosting, ultrasonic waves are generated at the lighting frequency of the lamp. The lighting frequency of this lamp is 30 kHz to 120 kHz, and actually, 40 kHz to 80 kHz is generally used. The frequency of ultrasonic generation used by the ultrasonic digitizer is generally 40 kHz to 80 kHz.

  Therefore, as shown in FIG. 11, if the receiver unit 3 other than the receiver unit 3 is housed in the housing A and the receiver unit 3 is housed in the housing B provided at a location different from the housing A, the inverter 22c The sound wave does not interfere with the reception ultrasonic wave of the reception unit 3. At this time, the receiving unit 3 is connected to the liquid crystal panel 21 in the housing A via the connection line m. Conventionally, the arrangement shown in FIG. 10 is used. However, the space of the housing in which the driving circuit (inverter 22c) of the backlight light source (lamp 22b) is accommodated by directly connecting the housing A and the housing B or further integrating these housings. And the space of the housing in which the receiving unit (receiving unit 3) is accommodated or shared, the ultrasonic wave from the drive circuit interferes with the received ultrasonic wave of the receiving unit, and the digitizer has an accurate position. The performance deteriorates so that cannot be specified.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to make a space of a housing in which a drive circuit of a backlight light source is accommodated and a space of a housing in which a receiving unit is accommodated. It is to realize an input / output integrated display device that is less likely to generate ultrasonic waves that cause interference noise to received ultrasonic waves of the receiving unit.

  In order to solve the above problems, an input / output integrated display display device of the present invention is an input / output integrated display display device using an ultrasonic digitizer and provided with a backlight light source. The backlight light source is boosted by an inverter circuit. The inverter circuit that is driven uses a wound coil as a boosting element.

  According to the above invention, since the inverter circuit, which is the drive circuit for the backlight light source, uses the wound coil as the boosting element, unlike the case of using the piezoelectric element, the interfering ultrasonic waves are not generated so much. Therefore, even if the ultrasonic receiving unit and the driving circuit for the backlight light source are arranged in a continuous or common space, there is no ultrasonic interference from the driving circuit to the receiving unit.

  As described above, even if the space of the housing in which the driving circuit of the backlight light source is accommodated and the space of the housing in which the receiving unit is accommodated are continuous or shared, the interference noise to the reception ultrasonic waves of the receiving unit Thus, there is an effect that it is possible to realize an input / output integrated display device that hardly generates ultrasonic waves.

  Further, since there is almost no interference, there is an effect that a great degree of freedom can be obtained in the arrangement of the ultrasonic receiving unit and the drive circuit of the backlight light source.

  In order to solve the above problems, the input / output integrated display device of the present invention is characterized in that the ultrasonic receiving unit and the inverter circuit are arranged in the same casing.

  According to the invention described above, since the ultrasonic receiving unit and the inverter circuit are arranged in the same housing, the input / output integrated display device can be reduced in size. Further, since the substrate of the receiving unit and the substrate of the inverter circuit can be made the same substrate, an effect that the input / output integrated display device can be made very small is achieved.

  In order to solve the above problems, an input / output integrated display display device of the present invention uses an ultrasonic digitizer, and the input / output integrated display display device includes a backlight light source, and the backlight light source is an LED. It is characterized by.

  According to the above invention, since the LED is used as the backlight light source, it is not necessary to use a boosting element, and unlike the case of using a piezoelectric element, no interfering ultrasonic wave is generated. Therefore, even if the ultrasonic receiving unit and the driving circuit for the backlight light source are arranged in a continuous or common space, there is no ultrasonic interference from the driving circuit to the receiving unit.

  As described above, even if the space of the housing in which the driving circuit of the backlight light source is accommodated and the space of the housing in which the receiving unit is accommodated are continuous or shared, the interference noise to the reception ultrasonic waves of the receiving unit Thus, there is an effect that an input / output integrated display device that does not generate ultrasonic waves can be realized.

  Further, since there is no interference, there is an effect that a great degree of freedom can be obtained in the arrangement of the ultrasonic receiving unit and the backlight light source driving circuit.

  In order to solve the above-mentioned problems, the input / output integrated display device of the present invention is characterized in that the ultrasonic receiving unit and the LED driving unit are arranged in the same casing.

  According to the above invention, since the receiving unit and the LED driving unit are arranged in the same housing, the input / output integrated display device can be reduced in size. Further, since the substrate of the receiving unit and the substrate of the LED drive unit can be made the same substrate, the input / output integrated display device can be very miniaturized.

  In the input / output integrated display device of the present invention, as described above, the backlight light source is boosted by an inverter circuit, and the inverter circuit uses a wound coil as a boosting element, or The light source is an LED.

  Therefore, even if the space of the housing in which the drive circuit for the backlight light source is accommodated and the space of the housing in which the reception unit is accommodated are continuous or shared, the interference noise to the reception ultrasonic waves of the reception unit Thus, there is an effect that it is possible to realize an input / output integrated display device that hardly generates or does not generate ultrasonic waves.

  Embodiments of the present invention will be described with examples.

  FIG. 1 shows a configuration of a digitizer device 1 which is an input / output integrated display device using the ultrasonic digitizer of the present embodiment.

  The digitizer device 1 includes a liquid crystal display 2, a receiving unit 3, and a pen 4. The liquid crystal display 2 includes a liquid crystal panel 21 and a backlight 22. The liquid crystal panel 21 is a display unit that performs input / output using an ultrasonic digitizer. Further, the backlight 22 includes a light guide plate 22a, a lamp (backlight light source) 22b, and an inverter (inverter circuit) 22c. Among these, the light guide plate 22 a and the lamp 22 b are provided on the back side of the liquid crystal panel 21. The lamp 22b is a cold cathode fluorescent tube (CCFT) or CFL (Cold Fluorescent Lamp) lamp. The receiving unit 3 includes an infrared receiving element 31, an ultrasonic receiving element 32, and an ultrasonic receiving element 33. The pen 4 includes an infrared transmission element 41 and an ultrasonic transmission element 42. The inverter 22c and the receiving unit 3 are provided outside the edge of the liquid crystal panel 21 so as to face each other with the liquid crystal panel 21 in between.

  In general, the material of the element that generates a high voltage in the inverter 22c is based on lead zirconate titanate ceramic (PZT) and is added with additives to improve performance. The

  In addition, the materials of the ultrasonic receiving element 32 and the ultrasonic receiving element 33 are based on lead zirconate titanate ceramic (PZT), with additives added to improve performance, PVDF ( A material having good workability, large area and easy thinning made from Polyvinylidene fluoride is used.

  A plan view of the digitizer device 1 of FIG. 1 is shown in FIG. The function of each member has been described in the description of FIG.

  Now, when the pen 4 is touched on the liquid crystal panel 21, a switch (not shown) in the pen 4 is turned on, and infrared rays are transmitted from the infrared transmission element 41 by ultrasonic control under the control of a microcomputer or the like inside the pen 4. Ultrasonic waves are output simultaneously from the element 42. The output infrared rays and ultrasonic waves are received by the infrared receiving element 31 and the ultrasonic receiving elements 32 and 33 arranged beside the liquid crystal panel 21. FIG. 3 shows a timing chart of received signals of infrared rays and ultrasonic waves. As described above, the pen 4 shown in FIG. 4 is detected by detecting the ultrasonic waves transmitted from the pen 4 by the two ultrasonic receiving elements 32 and 33 with the arrival signal to the infrared receiving element 31 as a reference. The distances L1 and L2 from the two to the two ultrasonic receiving elements 32 and 33 are calculated, and from the distance L0 between the two ultrasonic receiving elements 32 and 33, the coordinates of the pen 4 ( X, Y) is determined.

  In actual surveying, a total of three signal waveforms input to the infrared receiving element 31 and the two ultrasonic receiving elements 32 and 33 are amplified by the amplification circuits 41 to 43 as shown in FIG. Digitized by the circuits 51 to 53, digital data is further input to the calculation unit 60 such as a microcomputer, and the coordinates (X, Y) calculated by the calculation unit 60 are displayed on the liquid crystal panel 21.

  Next, in the ultrasonic receiving circuit of the ultrasonic digitizer, the difference in the degree of interference between the case where the winding type coil is used as the boosting element of the inverter used in the backlight and the case where the piezoelectric element is used will be described. .

For each of the winding type coil and the piezoelectric element, the distance between the receiving part and the lamp inverter was kept constant, and a comparative experiment was conducted to determine how the ultrasonic waves oscillated from the lamp inverter affect the receiving circuit. It was.
A 12-type TFT-LCD was used for the display panel.
1. A 4.0 W backlight inverter manufactured by TDK was used as the winding type inverter.
2. A 4.0 W backlight inverter manufactured by NEC TOKIN was used as the piezoelectric inverter.
In both cases, the ground of the inverter was connected to a housing which is a conductor on the back side. The receiving circuit is arranged on the left short side of the 12-type TFT-LCD, and the inverter is arranged on the lower long side.

The voltage peak values of each noise at this time are as follows.
0. Background (initial circuit noise) 60 mV
1. Winding type inverter 80mV
2. Piezoelectric inverter 750 mV
As can be seen from the above results, noise is small in the inverter using the winding type coil. The winding coil is mounted on an inverter that lights a cold cathode tube lamp used in a backlight for a liquid crystal display. Generally, it is a winding coil capable of outputting about 1 W to 7 W.

  Therefore, in this embodiment, the inverter 22c in FIG. 1 is an inverter using a winding coil. Since the inverter 22c, which is a drive circuit for the lamp 22b, uses a wound coil as a boosting element, unlike the case where a piezoelectric element is used, the interfering ultrasonic waves are not generated much. Therefore, even if the receiving unit 3 and the inverter 22c are arranged in a continuous or common space, there is no ultrasonic interference from the inverter 22c to the receiving unit 3.

  As described above, even if the space of the housing in which the inverter 22c is housed and the space of the housing in which the receiving unit 3 is housed are made continuous or common, interference noise to the reception ultrasonic waves of the receiving unit 3 is generated. Ultrasonic waves are not easily generated.

  6 to 8 show examples in which the receiving unit 3 of the digitizer apparatus 1 and the inverter 22c are arranged in the same casing C. FIG. In these drawings, a configuration in which the liquid crystal display 2 (= liquid crystal panel 21 + backlight 22) and the receiving unit 3 are combined is housed in a housing C.

  In FIG. 6, the receiving unit 3 and the inverter 22 c are arranged outside the two opposing short sides of the liquid crystal panel 21 so as to sandwich the liquid crystal panel 21. In FIG. 7, the receiving unit 3 is arranged outside one short side of the liquid crystal panel 21, and the inverter 22 c is arranged outside the one long side of the liquid crystal panel 21 so as to be juxtaposed with the lamp 22 b. Yes. In FIG. 8, the receiving unit 3 and the inverter 22 c are arranged so as to overlap the outside of one short side of the liquid crystal panel 21 so that the receiving unit 3 is on the upper side and the inverter 22 c is on the lower side.

  As described above, since there is almost no interference of ultrasonic waves, a large degree of freedom can be obtained in the arrangement of the receiving unit 3 and the inverter 22c as shown in FIGS. Further, since the receiving unit 3 and the inverter 22c are arranged in the same housing, the digitizer device 1 can be reduced in size. Furthermore, since the substrate of the receiving unit 3 and the substrate of the inverter 22c can be made the same substrate, the digitizer device 1 can be made very small.

  FIG. 9 shows a configuration of a digitizer device 11 that is an input / output integrated display device using the ultrasonic digitizer of this embodiment. Members having the same functions as those in the first embodiment are denoted by the same reference numerals.

  The digitizer device 11 is the same as the digitizer device 1 shown in FIG. 1 except that the backlight 22 is the backlight 5 and the backlight 5 and the liquid crystal panel 21 are the liquid crystal display 6. The backlight 5 includes a light guide plate 22a and an LED unit 22d. The LED 22d includes an LED that is a backlight light source and a drive circuit that drives the LED. Since the display operation of the digitizer device 11 is the same as that of the digitizer device 1, description thereof is omitted.

  In this embodiment, since an LED is used as the backlight light source, there is no need to use a boosting element used in the inverter circuit, and unlike the case where a piezoelectric element is used, interfering ultrasonic waves are not generated. Therefore, even if the receiving unit 3 and the LED driving circuit (LED unit 22d including the LED driving circuit in FIG. 9) are arranged in a continuous or common space, the driving circuit to the receiving unit 3 is connected to the receiving unit 3. There is no ultrasonic interference.

  As described above, the space of the housing that houses the LED drive circuit (LED unit 22d including the LED drive circuit in FIG. 9) and the space of the housing that houses the receiving unit 3 are continuous or shared. However, the ultrasonic wave which becomes interference noise to the reception ultrasonic wave of the receiving unit 3 is not generated.

  FIG. 10 shows an example in which the receiving unit 3 of the digitizer device 11 and the LED unit 22d are arranged in the same housing D. In this figure, a configuration in which the liquid crystal display 6 (= liquid crystal panel 21 + backlight 5) and the receiving unit 3 are combined is housed in a housing D. In addition, the receiving unit 3 is disposed outside one short side of the liquid crystal panel 21, and the LED unit 22 d is disposed outside one long side of the liquid crystal panel 21.

  As described above, since there is no ultrasonic interference, a large degree of freedom can be obtained in the arrangement of the receiving unit 3 and the LED unit 22d or the LED drive circuit. In addition, since the receiving unit 3 and the LED unit 22d or the LED drive circuit are arranged in the same housing, the digitizer device 11 can be reduced in size. Furthermore, since the substrate of the receiving unit 3 and the substrate of the LED unit 22d or the substrate of the LED drive circuit can be made the same substrate, the digitizer device 11 can be made very small.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view illustrating a first configuration of an input / output integrated display device according to an embodiment of the present invention. It is a top view which shows the layout of the member of the input-output integrated display display apparatus of FIG. It is a wave form diagram which shows the reception detection waveform of the infrared rays and ultrasonic wave of the input-output integrated display display apparatus of FIG. It is a top view which shows the detection method of the pen input coordinate by the three-point survey of an input-output integrated display display apparatus. It is a block diagram which shows the flow of the signal from the reception of the infrared rays and the ultrasonic wave of the input / output integrated display device of FIG. It is a disassembled perspective view which shows the 1st structural example which has arrange | positioned the receiving unit and inverter circuit of the input-output integrated display display apparatus of FIG. 1 in the same housing | casing. FIG. 5 is an exploded perspective view showing a second configuration example in which the receiving unit and the inverter circuit of the input / output integrated display device of FIG. 1 are arranged in the same housing. FIG. 10 is an exploded perspective view showing a third configuration example in which the receiving unit and the inverter circuit of the input / output integrated display device of FIG. 1 are arranged in the same housing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view illustrating a second configuration of an input / output integrated display device according to an embodiment of the present invention. FIG. 10 is an exploded perspective view showing a configuration example in which the receiving unit and the inverter circuit of the input / output integrated display device of FIG. 9 are arranged in the same housing. It is a disassembled perspective view which shows the prior art and shows the structural example which has arrange | positioned the receiving unit and inverter circuit of the input-output integrated display display apparatus in a separate housing | casing.

Explanation of symbols

1,11 Digitizer device (Input / output integrated display device)
3 Receiving unit 22b Lamp (Backlight light source)
22c Inverter (Inverter circuit)

Claims (4)

In an input / output integrated display device equipped with a backlight light source using an ultrasonic digitizer,
An input / output integrated display device characterized in that the backlight light source is boosted by an inverter circuit, and the inverter circuit uses a wound coil as a boosting element.   2. The input / output integrated display device according to claim 1, wherein the ultrasonic receiving unit and the inverter circuit are arranged in the same casing. In an input / output integrated display device equipped with a backlight light source using an ultrasonic digitizer,
The input / output integrated liquid crystal display device, wherein the backlight light source is an LED.   4. The input / output integrated display device according to claim 3, wherein the ultrasonic receiving unit and the LED driving unit are disposed in the same casing.

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