JP2004303980A - Electromagnetic shield device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic shield device simplified in structure yet capable of highly reliable electromagnetic interference inhibition. <P>SOLUTION: The device has a signal processing circuit 11 having inverters 13, 13 for generating signals reversed in phase from normal signals for display, a transmission channel 14 wherein lines for transmitting normal signals and reversed signals outputted by the signal processing circuit 11 are located adjacent to each other, and a liquid crystal display 15 into which the normal signals and reversed signals transmitted by the transmission channel 14 are inputted. The electromagnetic waves from the normal signal lines and those from the reversed signal lines are offset in the space accommodating the transmission channel 14, and this protects an interference-susceptible section 16 positioned near the transmission channel 14 from electromagnetic interference. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electromagnetic shield device that suppresses an adverse effect on other circuits and the like due to an electromagnetic wave generated on a signal line on a transmission line connecting two circuits.
[0002]
[Prior art]
For example, it is known that electromagnetic interference is generated in a transmission process of supplying a drive signal to a liquid crystal display panel, which adversely affects nearby circuits and the like.
[0003]
Conventionally, as a countermeasure against such electromagnetic interference, a technique of arranging a shield plate at a necessary place (for example, see Patent Document 1), a technique of keeping components susceptible to the electromagnetic interference away from the generation site, a drive signal The technology of changing the supply wiring pattern at the design stage, the technology of removing disturbing components with a filter, etc. have been used, but it is impossible to remove the disturbing components propagating in space to a level that does not cause problems, especially at low frequencies. It was very difficult.
[0004]
Techniques for detecting signal components of electromagnetic interference and creating components that are in phase opposite to the signal components in the device to cancel the electromagnetic interference have also been studied, but complicated techniques are required to improve accuracy. In practical use, the circuit scale becomes very large, such as a circuit configuration and a large amount of delay elements are required. Therefore, it cannot be applied to a small electronic device.
[0005]
[Patent Document 1]
JP-A-10-153766
[0006]
[Problems to be solved by the invention]
For example, in a radio-controlled wristwatch that corrects time by receiving a standard radio wave on which accurate time information is superimposed, many signal components are placed on a signal line that drives a display unit that displays time and the like. A lot of radiated interference from this portion occurs, which often affects the antenna for receiving the standard radio wave and causes a problem that accurate reception operation cannot be performed due to weak electrolysis or the like.
[0007]
For this reason, a method of temporarily stopping the display when receiving the standard radio wave has been considered, but it is incomplete as a product, and there is a demand for reliable removal of electromagnetic interference.
[0008]
However, even if the signal line portion is shielded, it is difficult to secure a sufficient thickness for the shield member in a wristwatch having a limited capacity (mounting area), and in particular, the frequency of electromagnetic interference can be reduced. Therefore, the thickness of the shield member is also necessary, and it is practically impossible to use a shield member having such a thickness.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electromagnetic shield device capable of reliably suppressing electromagnetic interference with a simpler configuration.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a first circuit having a generating means for generating an inverted signal whose phase is inverted from a normal signal to be output, and transmitting the normal signal output from the first circuit. A transmission line in which a normal signal line and an inverted signal line for transmitting the inverted signal are disposed close to each other, and a second circuit for inputting the normal signal and the inverted signal sent via the transmission line. The electromagnetic wave generated in the forward signal line and the electromagnetic wave generated in the inverted signal line cancel each other out in the space where the transmission line is located, thereby preventing electromagnetic interference to a disturbed portion arranged near the transmission line. It is characterized by prevention.
[0011]
With such a configuration, simply adding a simple circuit and signal lines such as an inverter cancels out the electromagnetic waves generated in the space where each signal line is located by each signal line, thereby reliably suppressing electromagnetic interference. Becomes possible.
[0012]
According to a second aspect of the present invention, in the second aspect of the invention, in the second circuit, the terminal of the inverted signal line is substantially equivalent to a load connected to the terminal of the non-inverted signal line. It is characterized in that it is connected to a load.
[0013]
With such a configuration, in addition to the operation of the invention described in claim 1, the behavior at the time of signal transmission on the inversion signal line is exactly inverted from the behavior at the time of information transmission on the forward signal line. And more reliably canceling out the electromagnetic waves generated in the two lines and reducing the electromagnetic interference to a sufficient level.
[0014]
According to a third aspect of the present invention, in the first aspect of the present invention, a terminal of the inverted signal line is opened in the second circuit.
[0015]
With such a configuration, in addition to the effect of the first aspect of the present invention, when the load connected to the terminal of the non-inverting signal line in the second circuit is sufficiently light, the circuit configuration is further improved. Electromagnetic interference can be suppressed to some extent while simplifying.
[0016]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the generation means of the first circuit generates a signal having one phase inverted corresponding to the sum of a plurality of signals to be output. The transmission line is characterized in that one inversion signal line is disposed close to the plurality of normal signal lines.
[0017]
With such a configuration, in addition to the effect of the invention described in claim 1, the same effect can be obtained even when the number of usable signal lines and the number of terminals of the first and second circuits are limited. Can be.
[0018]
According to a fifth aspect of the present invention, in the first aspect of the present invention, the transmission line has a normal signal line and an inverted signal line opposed to each other via an insulating material.
[0019]
With such a configuration, in addition to the operation of the invention described in claim 1, for example, a transmission path can be formed using both front and back surfaces such as a flexible circuit board and a liquid crystal glass surface. It can be easily applied to places where the grounding cannot be performed well, and can cope with low frequency interference components.
[0020]
According to a sixth aspect of the present invention, in the invention of the fifth aspect, at least one of the normal signal line and the inverted signal line of the transmission line is formed in a zigzag line pattern bent along the other line. It is characterized by having.
[0021]
With such a configuration, in addition to the operation of the invention described in claim 5, the generated magnetic flux component is more effectively removed as compared to a case where both lines are simply laid in parallel in a straight line. be able to.
[0022]
According to a seventh aspect of the present invention, in the first aspect of the invention, the second circuit executes an output operation based on both a signal input through a normal signal line and an inverted signal line of the transmission line. It is characterized by doing.
[0023]
With such a configuration, in addition to the operation of the first aspect of the present invention, not only can the generated inverted signal be effectively used, but also the loads on both lines in the second circuit can be made substantially equal. Therefore, the electromagnetic waves generated in both lines can be more reliably canceled to reduce the electromagnetic interference to a sufficient level.
[0024]
In the invention described in claim 8, in the invention described in claim 7, the first circuit is a liquid crystal display panel drive, and the second circuit divides one display pixel into two segments. A liquid crystal display panel having a structure in which two segments forming one display pixel are driven and displayed based on both a signal input through the normal signal line and a signal input through the corresponding inverted signal line. .
[0025]
With this configuration, in addition to the effect of the invention described in claim 7, apparent display definition can be increased, and display quality can be improved.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a case where the present invention is applied to a liquid crystal display device will be described as a first embodiment with reference to the drawings.
[0027]
FIG. 1 shows the concept of the basic configuration according to the present embodiment. In FIG. 1, reference numeral 11 denotes a signal processing circuit for performing display and other signal processing, and a display driver 12 for generating a display drive signal is provided in the signal processing circuit 11.
[0028]
In this display driver 12, while the drive signals a, b, and な required for the liquid crystal display unit 13 to be driven are output as they are in the normal rotation, the phase of each signal is controlled by the inverters 13, 13, and ‥‥. The inverted signal is generated and output. The forward signal and the inverted signal are output to the liquid crystal display unit 15 via the transmission line 14.
[0029]
In the following description and drawings, for example, an inverted signal obtained by inverting the phase of the normal signal “a” by the inverter 13 is expressed as “−a”.
Since the phases of the original signals “a” and “−a” are opposite to each other, the electromagnetic interference component D1 generated from the signal line of the normal rotation signal “a” on the transmission line 14 and the inverted signal “ The electromagnetic interference component D2 generated from the signal line “−a” has the same waveform and a phase relationship opposite to each other.
[0030]
Therefore, even if a disturbed portion 16 (for example, an antenna if this liquid crystal display device is employed in a radio-controlled wristwatch) is provided in the vicinity of the transmission path 14, the above-described electromagnetic interference can be prevented. The components D1 and D2 cancel each other, and the effect on the disturbed portion 16 is nullified.
[0031]
The above is not limited to the signal lines of the normal rotation signal “a” and the inversion signal “−a”, but also applies to all the signal lines constituting the transmission line 14.
[0032]
As a result, for the disturbed portion 16 disposed near the transmission line 14, the electromagnetic interference generated from the entire transmission line 14 cancels each other and is almost nullified, so that the predetermined electromagnetic interference is not adversely affected. Function can be performed.
[0033]
In addition, especially with respect to the low frequency component of the electromagnetic interference, the distance between the transmission line 14 and the disturbed portion 16 is considered to be sufficiently small compared to the wavelength thereof, so that the influence on the disturbed portion 16 is similarly invalidated. Can be expected.
[0034]
Next, the processing of the transmission line 14 end in the liquid crystal display unit 15 will be described.
[0035]
FIG. 2 shows an example in which the end of the normal signal line of the transmission line 14 is connected to the liquid crystal panel terminal 15a in the liquid crystal display unit 15, while the end of the inverted signal line is connected to the other end of the capacitance C having one end grounded. It is shown.
[0036]
By setting the capacitance value of the capacitance C to correspond to each pixel (segment) of the liquid crystal display panel, the behavior at the time of signal transmission on the inverted signal line and the behavior at the time of signal transmission on the non-inversion signal line are accurately reversed. Since they can be in phase, the electromagnetic interference can also be canceled out by canceling each other out.
[0037]
FIG. 3 exemplifies a wiring pattern in the case where the liquid crystal display section 15 performs segment display of the static drive system. 3A shows the wiring pattern of the upper transparent signal electrode with the liquid crystal layer interposed therebetween, and FIG. 3B shows the wiring pattern of the lower transparent scanning electrode.
[0038]
Here, in the upper signal electrode, eight segments including the seven segments forming the character “8” and one segment indicating the decimal point are driven by the normal signal lines “a” to “h”, and each normal signal is driven. Corresponding inverted signal lines "-a" to "-h" are wired along the lines and electrodes, and the ends thereof are connected with capacitances C as pseudo loads equivalent to the respective segments as shown in FIG. are doing.
[0039]
The lower scan electrode is constituted by only one segment corresponding to all the upper segments because of the static drive, and is driven by the forward signal line i and along the forward signal line "i" and the electrode. In this way, the inverted signal line "-i" is wired, and at its end, the capacitance C is connected as a pseudo load equivalent to one segment corresponding to all the upper segments as shown in FIG.
[0040]
FIG. 4 illustrates a wiring pattern in the case where the liquid crystal display unit 15 performs a segment display of a dynamic drive system. FIG. 4A shows the wiring pattern of the upper transparent signal electrode with the liquid crystal layer interposed therebetween, and FIG. 4B shows the wiring pattern of the lower transparent scanning electrode.
[0041]
Here, in the upper signal electrode, 7 segments forming the character "8" and 1 segment indicating the decimal point, that is, 8 segments are divided into 4 groups of 2 segments each, and the normal signal lines "a" to "d" ], And the corresponding inverted signal lines "-a" to "-d" are wired along the normal signal lines and the electrodes, and at the ends thereof, as shown in FIG. Are connected as pseudo loads equivalent to the capacitance viewed from the respective non-inverted signal lines of “a” to “d”.
[0042]
The lower scan electrode is divided into two so as to have a different division pattern from all the upper segments because of the dynamic drive, and is driven by the normal rotation signal lines “e” and “f”. The inverted signal lines "-e" and "-f" are wired along the inverted signal lines "e" and "f" and the electrodes, and the capacitance C is changed to "e" at each end as shown in FIG. , And "f" are connected as pseudo loads equivalent to the capacitance as viewed from the normal signal lines.
[0043]
In each of FIGS. 2 to 4, it is assumed that each segment constituting the liquid crystal panel of the liquid crystal display unit 15 is a load having a capacitance component, and an equivalent capacitance C serving as a pseudo load is connected to each inverted signal line. However, if the load connected to the non-inverting signal line is not a capacitance component, or if the capacitance component is replaced with a resistance load and has an appropriate effect on electromagnetic interference, the capacitance C Instead, a resistor may be connected to the end of each inverted signal line.
[0044]
FIG. 5 shows an example in which the end of the normal signal line of the transmission line 14 is connected to the liquid crystal panel terminal 15a in the liquid crystal display unit 15, while the end of the inverted signal line is connected to the other end of a resistor R having one end grounded. It is shown.
[0045]
By setting the impedance value of the resistor R to correspond to each pixel (segment) of the liquid crystal display panel, the behavior at the time of signal transmission on the inverting signal line is exactly opposite to the behavior at the time of signal transmission on the normal signal line. The electromagnetic interference can be canceled out and nullified.
[0046]
The specific wiring pattern is the same as the case shown in FIGS. 3 and 4, and the same effect can be obtained by replacing the capacitance C with the resistor R.
[0047]
Further, when the load on the liquid crystal display unit 15 side is extremely small and has a negligible level, the terminal of each inversion signal line may be intentionally opened instead of the capacitance C and the resistance R.
[0048]
FIG. 6 shows an example in which the end of the normal signal line of the transmission line 14 is connected to the liquid crystal panel terminal 15a in the liquid crystal display unit 15, while the end of the inverted signal line is opened.
[0049]
By opening the end of each inversion signal line in this way, it is possible to suppress electromagnetic interference while simplifying the circuit configuration.
[0050]
Next, the configuration of the transmission line 14 will be specifically described.
[0051]
FIG. 7 shows a flexible circuit board (FPC) 21 in which a normal signal line 22 is printed on the upper surface and an inverted signal line 23 is printed on the lower surface.
[0052]
In this way, by arranging the normal rotation signal line 22 and the reverse rotation signal line 23 in parallel and opposed to each other with the flexible circuit board 21 as an insulating material therebetween, the opposite-phase electromagnetic waves generated in both lines can be accurately canceled. Thus, the influence on the disturbed portion 16 located near the transmission path 14 can be nullified. Note that the transmission paths 14 are arranged on the same plane.
[0053]
In addition, since the transmission path 14 is configured using the flexible circuit board 21 having flexibility, the transmission path 14 can be easily applied to places where shielding is difficult or where grounding of the shield is not properly achieved.
[0054]
In this case, both the normal signal line 22 and the inverted signal line 23 may have a linear wiring pattern. For example, as shown in FIG. On the other hand, the inverted signal line 23 'may be formed to have a zigzag pattern in which the inverted signal line 23' is bent along the normal signal line 22 '(with the flexible circuit board 21 interposed).
[0055]
Further, both the normal signal line 22 and the inverted signal line 23 may be formed in a zigzag pattern in which both of them are bent.
[0056]
By forming such a zigzag pattern, it is possible to more effectively remove the generated magnetic flux component than when simply laying both straight lines in parallel.
[0057]
Although FIGS. 7 and 8 have described the case where the normal signal line 22 and the inverted signal line 23 are laid on the flexible circuit board 21, the present invention is not limited to this. For example, the glass forming the liquid crystal display panel may be used. In the same manner as the case of forming the pixel (segment) electrode, the normal signal line and the inverted signal line may be formed using a transparent conductive film such as an ITO film.
[0058]
In particular, in the case of a device in which the total number of signal lines in the transmission path 14 is limited, the number of non-inverting signal lines and the number of inverting signal lines do not have to correspond to 1: 1.
[0059]
FIG. 9 shows an example in which one inverted signal line is provided for each of a plurality of, for example, three normal signal lines, and an inverted signal is generated from the total value. In this case, the display driver 12 ″ outputs, for example, the first three forward rotation signals a to c as they are, calculates the total value “(a + b + c)” from these signals by the summation circuit 18, and calculates the result. The inverted signal is inverted by the inverter 13 to generate an inverted signal g (= − (a + b + c)), and is output to the liquid crystal display unit 15 by a line along the line of the normal rotation signals a to c.
[0060]
The same applies to the non-inverted signals d to f. Hereinafter, one inverted signal line is provided for every three non-inverted signal lines, and the inverted signal generated from the total value of the non-inverted signals is converted into the corresponding inverted signal. Is transmitted to the liquid crystal display unit 15 via the inverted signal line laid along the line.
[0061]
As described above, even when the number of usable signal lines and the number of input / output terminals of the signal processing circuit 11 and the liquid crystal display unit 15 are limited, each signal line can be simply added by adding a simple arithmetic circuit and signal lines. Cancels out the electromagnetic waves generated in the space where the transmission line is located, and can reliably suppress the electromagnetic interference.
[0062]
(Second embodiment)
Hereinafter, a case where the present invention is applied to a radio-controlled wristwatch will be described as a second embodiment with reference to the drawings.
[0063]
FIG. 10 shows the circuit configuration, and reference numeral 31 denotes a control unit that controls all operations. The control unit 31 fixes a CPU, a program for executing a correction operation for receiving the standard time signal on which the CPU has a timekeeping operation and accurate time information and correcting the current time information held by the timekeeping operation, and the like. The control unit 31 is connected to a key input unit 32, an oscillating unit 33, a timer unit 34, a receiving unit 35, and a display driving unit 36.
[0064]
The key input unit 32 includes, for example, several key button switches arranged on the outer peripheral portion of the housing of the wristwatch, and directly inputs an operation signal corresponding to a pressing operation to the control unit 31.
[0065]
The oscillating unit 33 drives the crystal oscillator to oscillate a reference clock of, for example, 32768 [Hz]. Based on the oscillation of the oscillation unit 33, the clock unit 34 measures the current time, that is, the year, month, day, hour, minute, and second, and updates and retains the time information.
[0066]
The receiving unit 35 is provided with an antenna 37 incorporated in the timepiece housing to provide accurate information at a preset time every day, for example, 2:00 am, and when a time correction is instructed by a key operation of the key input unit 32 at any time.
A standard radio wave on which time information is carried is received, the time information is taken out, and transmitted to the control unit 31.
[0067]
The display driving unit 36 generates a normal rotation signal and an inversion signal for driving the display of the liquid crystal display unit 38 based on the display data given from the control unit 31, and supplies these signals to the liquid crystal display panel terminals of the liquid crystal display unit 38. To drive the display.
[0068]
However, the liquid crystal driving section 36 corresponds to the signal processing circuit 11 having the principle configuration in FIG. 1 and the liquid crystal display section 38 corresponds to the liquid crystal display section 15.
[0069]
FIG. 11 illustrates a part of a wiring pattern in the case where the liquid crystal display section 38 performs a segment display of a static drive system. FIG. 11A shows the wiring pattern of the upper transparent signal electrode with the liquid crystal layer interposed therebetween, and FIG. 11B shows the wiring pattern of the lower transparent scanning electrode.
[0070]
Here, in the upper signal electrode, 7 segments constituting the character “8” and 1 segment indicating the decimal point, that is, 8 segments in total, are divided into two portions, and the segment portion indicated by coarse hatching rising to the right in the figure is shown. Driving is performed by the non-inverting signal lines "a" to "h", and a segment indicated by dense hatching in the lower right in the figure is driven by the inverting signal lines "-a" to "-h".
[0071]
Since the lower scan electrode is of the static drive type, all the upper segments correspond to the segment portions corresponding to the inverted signal lines "a" to "h" and the inverted signal lines "-a" to "-h". It is composed of two segments divided into two segments, and is driven by the normal signal line “i” and the inverted signal line “−i”.
[0072]
FIG. 12 illustrates a part of a wiring pattern in a case where the liquid crystal display section 38 performs a segment display of a dynamic drive system. FIG. 12A shows the wiring pattern of the upper transparent signal electrode with the liquid crystal layer interposed therebetween, and FIG. 12B shows the wiring pattern of the lower transparent scanning electrode.
[0073]
In the upper signal electrode shown in FIG. 12 (A), 8 segments are divided into 4 groups of 2 segments each including 7 segments forming the character “8” and 1 segment indicating a decimal point, and each segment is divided into four groups. It is divided into two along the axial direction, and is divided into a segment driven by a forward rotation signal indicated by coarse hatching rising to the right in the figure and a segment driven by an inverted signal indicated by dense hatching falling to the right in the figure. are doing.
[0074]
Therefore, the four segment groups are driven by the normal signal lines “a” to “d” and the inverted signal lines “−a” to “−d”.
[0075]
The lower scanning electrode shown in FIG. 12B is divided into two so as to have a division pattern different from that of all the upper segments because of the dynamic driving, and the segment driven by the normal rotation signal and the inverted one are used. It is further divided into two so as to correspond to segments driven by signals, and is driven by normal signal lines "e" and "f" and inverted signal lines "-e" and "-f".
[0076]
FIG. 13 exemplifies a driving waveform when one segment driven by the normal rotation signal and one segment adjacent to the segment and driven by the inverted signal are driven. Here, a driving waveform of a voltage averaging method of the バ イ ア ス bias method, which is a basic driving method of the segment display of the dynamic driving, is exemplified.
[0077]
Assuming that the waveform of the scanning electrode driven by the normal rotation signal line is Vx (x = e, f) as shown in FIG. 13A, the scanning driven by the corresponding inversion signal line as shown in FIG. It can be seen that the waveform of the electrode is -Vx, which is completely out of phase.
[0078]
On the other hand, assuming that the waveform of the signal electrode driven by the non-inverting signal line is Vy (y = a to d) as shown in FIG. 13C, the corresponding inversion signal as shown in FIG. It can be seen that the waveform of the signal electrode driven by the line is -Vy, which is also completely out of phase.
[0079]
As a result, as shown in FIG. 13 (5), the waveform of the segment driven by the normal rotation signal is “Vx−Vy”, and the “half-selected state”, “selected state”, “half-selected state”, and “non-selected state” Is one cycle, and the display driving is performed.
[0080]
Similarly, as shown in FIG. 13 (6), the waveform of the segment driven by the inversion signal is “− (Vx−Vy)”, and the “half-selected state”, “selected state”, “half-selected state”, and “non-selected state” It can be seen that the display drive is performed with the “selection state” as one cycle, and the drive waveform of the segment driven by the normal rotation signal is completely in reverse phase.
[0081]
Thus, not only can the inverted signal generated by the liquid crystal display unit 38 be effectively used by the liquid crystal display unit 38, but also the loads on both lines can be made substantially equal by the liquid crystal display unit 38.
[0082]
Therefore, the electromagnetic waves generated on both the normal signal line and the inverted signal line are more reliably canceled, and the electromagnetic interference when the antenna 37 receives the standard radio wave on which the time information is superimposed is reduced to a sufficient level. be able to.
[0083]
In each of the first and second embodiments, a case has been described in which a segment-type liquid crystal display is driven. However, the present invention can be easily applied to a device for driving a dot-matrix type liquid crystal display. .
[0084]
Furthermore, the present invention is not limited to a liquid crystal display unit and a circuit for outputting a drive signal thereof, but also provides a printer or a sound emitting unit having a speaker, an indicator unit using an LED or the like, and outputs a drive signal to any output circuit and its output circuit. It can be applied to a signal processing circuit to be supplied in a similar manner.
[0085]
In addition, the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the gist thereof.
[0086]
Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some components are deleted from all the components shown in the embodiments, at least one of the problems described in the column of the problem to be solved by the invention can be solved and the effects described in the column of the effect of the invention can be solved. When at least one of the effects described above is obtained, a configuration from which this component is deleted can be extracted as an invention.
[0087]
【The invention's effect】
According to the first aspect of the present invention, by simply adding a simple circuit such as an inverter and a signal line, each signal line cancels out the electromagnetic waves generated in the space where the transmission line is located, and reliably suppresses the electromagnetic interference. It is possible to do.
[0088]
According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the behavior at the time of signal transmission on the inverted signal line is exactly inverted from the behavior at the time of information transmission on the forward signal line. In this case, the electromagnetic waves generated in the two lines are more reliably canceled to reduce electromagnetic interference to a sufficient level.
[0089]
According to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, when the load connected to the non-inverting signal line terminal in the second circuit is sufficiently light, the circuit configuration Can be further simplified, and electromagnetic interference can be suppressed to some extent.
[0090]
According to the fourth aspect of the invention, in addition to the effect of the first aspect of the invention, the same effect can be obtained even when the number of usable signal lines and the number of terminals of the first and second circuits are limited. Obtainable.
[0091]
According to the fifth aspect of the invention, in addition to the effects of the first aspect of the invention, for example, a transmission path can be formed using both the front and back sides of a flexible circuit board, a liquid crystal glass surface, or the like. It can be easily applied to places where the grounding of shields or shields cannot be taken well, and it can cope with low frequency interference components.
[0092]
According to the invention of claim 6, in addition to the effect of the invention of claim 5, the generated magnetic flux component can be more effectively reduced as compared with the case where both lines are simply laid in parallel in a straight line. Can be removed.
[0093]
According to the seventh aspect of the invention, in addition to the effect of the first aspect of the invention, not only can the generated inverted signal be effectively used, but also the loads on both lines in the second circuit can be made substantially equal. Therefore, the electromagnetic waves generated in both lines can be more reliably canceled, and the electromagnetic interference is reduced to a sufficient level.
[0094]
According to the invention of claim 8, in addition to the effect of the invention of claim 7, the apparent display definition can be increased, and the display quality can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the concept of a basic configuration according to a first embodiment of the present invention.
FIG. 2 is a view exemplifying a load process at the end of an inverted signal line according to the embodiment;
FIG. 3 is a diagram illustrating a case where the load processing of FIG. 2 is applied to a segment display of a static drive system.
FIG. 4 is a diagram illustrating a case where the load processing of FIG. 2 is applied to a segment display of a dynamic drive system.
FIG. 5 is a view exemplifying another load processing of the inverted signal line end according to the embodiment;
FIG. 6 is a view exemplifying another load processing of the inverted signal line end according to the embodiment;
FIG. 7 is an exemplary sectional view illustrating a specific configuration of the transmission line according to the embodiment;
FIG. 8 is a view exemplifying another specific configuration of the transmission line according to the embodiment;
FIG. 9 is an exemplary view showing another concept of the basic configuration according to the embodiment;
FIG. 10 is a block diagram showing a circuit configuration of an entire radio-controlled wristwatch according to a second embodiment of the present invention.
11 is a diagram illustrating a case where the liquid crystal display unit of FIG. 10 is applied to a segment display of a static drive system.
12 is a diagram illustrating a case where the liquid crystal display unit of FIG. 10 is applied to a segment display of a dynamic drive system.
FIG. 13 is a view exemplifying a driving waveform of a voltage averaging method for driving each segment in FIG. 12;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Signal processing circuit, 12 and 12 "... Display driver, 13 ... Inverter, 14 ... Transmission line, 15 ... Liquid crystal display part, 16 ... Disturbed part, 17 ... Averaging circuit, 18 ... Total circuit, 21 ... Flexible circuit Substrate, 22, 22 '... normal signal line, 23, 23' ... inverted signal line, 31 ... control unit, 32 ... key input unit, 33 ... oscillation unit, 34 ... clock unit, 35 ... reception unit, 36 ... display Driving unit, 37 antenna, 38 liquid crystal display unit, C capacitance, D1, D2 electromagnetic interference component, R resistance.

Claims (8)

A first circuit having a generating means for generating an inverted signal whose phase is inverted from a normal signal to be output;
A transmission line, which is provided with a normal signal line for transmitting a normal signal and an inverted signal line for transmitting the inverted signal, which are output by the first circuit;
A second circuit for inputting a normal signal and an inverted signal sent through the transmission line, and transmitting the electromagnetic wave generated on the normal signal line and the electromagnetic wave generated on the inverted signal line to the transmission circuit. An electromagnetic shield device that cancels out in a space where a path is located, and prevents electromagnetic interference to a disturbed portion disposed near the transmission path. 2. The electromagnetic shield device according to claim 1, wherein, in the second circuit, a terminal of the inverted signal line is connected to a load substantially equivalent to a load connected to a terminal of the normal signal line. . 2. The electromagnetic shield device according to claim 1, wherein an end of the inverted signal line is opened in the second circuit. The generating means of the first circuit generates a signal with one phase inverted corresponding to the sum of a plurality of signals to be output,
2. The electromagnetic shield device according to claim 1, wherein the transmission path includes one inverting signal line disposed close to the plurality of normal signal lines. 2. The electromagnetic shield device according to claim 1, wherein the transmission path has a normal signal line and an inverted signal line opposed to each other with an insulating material interposed therebetween. 6. The electromagnetic shielding device according to claim 5, wherein at least one of the normal signal line and the inverted signal line of the transmission path has a zigzag line pattern bent along the other line. 2. The electromagnetic shield device according to claim 1, wherein the second circuit performs an output operation based on both signals input through a normal signal line and an inverted signal line of the transmission line. The first circuit is a liquid crystal display panel drive,
The second circuit is a liquid crystal display panel configured by dividing one display pixel into two segments,
8. The electromagnetic shield device according to claim 7, wherein two segments forming one display pixel are driven and displayed based on both the signal input through the normal signal line and the signal input through the corresponding inverted signal line. .

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