JP6915246B2 - Display device - Google Patents

Description

The present invention relates to a display device provided with a tuner device for receiving, for example, television broadcasting, and more particularly to an improvement in a technique for reducing unnecessary radiation (EMI: Electro-Magnetic Interference) from a metal housing of the tuner device.

Conventionally, as a display device for reducing unnecessary radiation, Patent Document 1 describes each of the vertical, horizontal, depth, and diagonal (straight line distances between the farthest vertices) of a shield case (metal housing) accommodating a tuner IC. A configuration is adopted in which all the dimensions are set shorter than the half wavelength of the highest frequency among the source oscillation frequencies of the oscillation unit of the tuner IC to be accommodated.

Further, in Patent Document 2, in the central portion of the upper surface of the conductor shield (housing) in which the electronic component is sealed, the central portion of the upper surface and the ground of the circuit board are connected by a plurality of conductor columns, and in those conductor columns. By adopting a configuration in which the distance between the conductor columns is set to be 1/4 or less of the wavelength at the maximum operating frequency, unnecessary radiation caused by resonance of the conductor shield is reduced.

Further, in Patent Document 3, conductive posts (grounding posts) connecting the metal housing and the printed circuit board are evenly arranged inside the housing, or as much as possible along the edge of the housing. It is arranged evenly, and the spacing between the grounding posts is set to one-fourth or less of the wavelength of the electromagnetic wave corresponding to the frequency at which EMI is not desired to be generated.

Japanese Unexamined Patent Publication No. 2015-109551 International release WO2015 / 119151A1 Japanese Unexamined Patent Publication No. 2007-299099

However, in recent years, although the tuner ICs provided in tuner devices have been integrated and miniaturized, there is a limit to the miniaturization of capacitors and inductors accommodated in the metal housing. There is a limit to the size such as depth and diagonal. On the other hand, with the miniaturization of capacitors built into ICs, the oscillation frequency of the voltage controlled oscillator (VCO) housed in the metal housing is as high as several to a dozen GHz, for example, for receiving TV broadcasts. Therefore, due to this relationship, the half value (λ / 2) of the wavelength λ of the signal having the highest oscillation frequency becomes an extremely small value. Therefore, even if the vertical, horizontal, depth, and diagonal sizes of the metal housing are set to half the wavelength (λ / 2) or less of the signal having the highest oscillation frequency of the VCO as in the technique described in Patent Document 1. In reality, it is quite difficult, and as a result, a portion having a high impedance is generated in the metal housing, and a large amount of unnecessary radiation is generated from this portion.

Further, in the technique described in Patent Document 1, the diagonal dimension (straight distance between the farthest vertices) of the housing, for example, the upper left corner of the front surface of the square housing and the upper right of the rear surface facing the front surface. Even if it is assumed that the linear distance connecting the corners is less than half the wavelength (λ / 2) of the signal with the highest oscillation frequency of VCO, for example, the lower left corner of the front surface of the housing and the lower right corner of the rear surface can be set. When grounded, the conductor shield resonates with the total dimension of twice the height of the square housing and the diagonal length of the upper surface of this housing, so this total dimension is half of the signal with the highest oscillation frequency. It also results in large unwanted radiation that greatly exceeds the wavelength (λ / 2).

Further, in the technique described in Patent Document 2 and the technique described in Patent Document 3, the number of grounding posts is increased because the grounding posts are arranged as evenly as possible along the inside and the end of the housing. There is a drawback that the number is large, the configuration is complicated, and the price is high.

In view of the above points, an object of the present invention is to display a display device in which a housing for accommodating an oscillation unit is connected to the ground of a substrate, and the size of the housing such as vertical and horizontal is half of the maximum oscillation frequency of the oscillation unit. Even when the wavelength is longer than the wavelength (λ / 2), the impedance can be lowered anywhere in the housing while reducing the number of grounding points, so that unnecessary oscillation can be effectively reduced.

In order to achieve the above object, in the present invention, unnecessary radiation is inevitably generated in the housing portion having high impedance with the grounded portion of the housing as the reference impedance. Therefore, the housing portion having high impedance is used as much as possible. It is configured to be eliminated to reduce unwanted radiation.

That is, the display device of the invention according to claim 1 includes an oscillating unit that outputs an oscillating signal, a signal processing unit that processes a high-frequency signal, a display unit that displays an image, and the signal processing unit are arranged and grounded. A substrate having a portion and a conductive housing connected to a first portion of the ground portion and a second location different from the first location are provided, and in the housing , the first portion and the ground portion are provided. A predetermined first high impedance condition is obtained by locating the first region and the second region, respectively, in a region separated from the second location by an odd multiple of 1/4 of the wavelength of the oscillation signal. the filled, the the first location, wherein the housing that satisfies a first region of a given said first high impedance satisfying the housing, by said second location, a predetermined first high impedance condition the distance between the second region and overlaps two points of the body, characterized in that it is arranged on the wavelength becomes lambda / 10 or less as lambda position of the oscillating signal.

In the invention according to claim 1, the first and second ground connection points provided in the housing overlap with the first and second regions having high impedance due to the two grounding points in the housing. Since the distance between the points is arranged at a position where the wavelength of the oscillation signal is λ and is λ / 10 or less, the range of the first region and the second region having high impedance is the narrow range of the housing as a whole. Can fit within the area. Therefore, when lowering the impedance of the high impedance region in the narrow range, it is sufficient to lower the impedance only in the narrow range, which has the effect of facilitating design .

Display of the invention請Motomeko second aspect, comprises an oscillation unit for outputting an oscillation signal, a signal processing unit for processing a high frequency signal, and a display unit for displaying an image, said signal processing unit is arranged, the ground portion A substrate having a only separate areas odd multiple distance of 1/4 of that first region is located, satisfy a predetermined first high impedance condition, the in housing, the second is located in the ground outer By locating the second region in a region separated from the location by an even multiple of 1/4 of the wavelength of the oscillation signal , a predetermined second high impedance condition is satisfied, and the predetermined location satisfies the predetermined second high impedance condition. Between two points where the first region of the housing satisfying the first high impedance condition and the second region of the housing satisfying the predetermined second high impedance condition are overlapped by the second location. Is arranged at a position where the distance is λ / 10 or less with the wavelength of the oscillating signal as λ .

And in the invention of claim 2 Symbol placement, although the first region and the second region becomes the other regions more high impedance region than the casing, it is possible to limit these regions less.

Further, since the first and second locations of the housing are arranged so that the distance between the two points where the first region and the second region overlap is λ / 10 or less of the wavelength λ of the oscillation signal. , It is possible to effectively reduce some or all of these first and second regions.

The invention according to claim 3 is characterized in that the wavelength of the oscillation signal is the wavelength at the lowest frequency in the frequency variable range of the oscillation unit.

In the invention according to claim 3 , even if the two high impedance regions are located farthest from the first and second locations, the distance between the two overlapping points of the two high impedance regions is the second. Since it is below the threshold, these high impedance regions can be reliably limited to a small number.

The invention according to claim 4 is characterized in that an extension line connecting the housing and the first location is provided, and the first location is arranged at a position separated from the housing.

The invention according to claim 5 is characterized in that an extension line connecting the housing and the second location is provided, and the second location is arranged at a position separated from the housing.

In the inventions of claims 4 and 5 , since the first and second locations are arranged at positions separated from the housing, the high impedance generated in the housing by the first and second locations is obtained. The distance between two points where the first region and the second region overlap can be easily set to be equal to or less than the second threshold value.

The invention according to claim 6 is characterized in that the housing is arranged in a predetermined area of the substrate, and the second portion is arranged in a predetermined area of the substrate.

In the invention according to claim 6 , even when the second location is arranged at a position away from the housing, the second location is arranged in a predetermined area of the substrate on which the housing is arranged. Even if other components of the tuner device, such as digital processing circuits and audio circuits, are placed close to each other on the side of the housing, the grounding point is not disturbed by these components. Can be placed away from the housing.

The invention according to claim 7 includes a connector portion provided in the housing and to which a signal cable is connected, and the first region and the second region are located at locations separated from the connector portion by a predetermined distance or more. It is characterized by that.

In the invention according to claim 7 , for example, even in a housing in which a signal cable for television broadcasting is connected to a connector portion, a first region and a second region having high impedance are provided at locations away from the connector portion. Since it is located, the impedance distribution on the housing is not easily affected by the variation in the state (type, material, shape, etc.) of the signal cable, and the generation of unnecessary radiation due to the variation in the state of the signal cable can be suppressed.

In the invention according to claim 8 , the substrate has a third portion, and in the third location, the third region of the housing whose impedance is lower than a predetermined threshold value by the third location is the first region. And, it is characterized in that it is arranged so as to overlap at least one of the second regions.

In the invention according to claim 8 , the third portion is arranged on the substrate so that the third region having low impedance overlaps at least one of the first region and the second region having high impedance in the housing. Unwanted radiation from the first region or the second region will be effectively reduced.

In the invention according to claim 9 , the third location is connected to the ground portion, and the third region is a distance of an even multiple of 1/4 of the wavelength of the oscillation signal from the third location in the housing. It is characterized in that it is located only in a distant area.

In the invention according to claim 9 , the third region is connected to the ground portion, and the third region is located in a region separated from the third location by an even multiple of 1/4 of the wavelength of the oscillation signal. Therefore, the first region or the second region having high impedance can be surely made low impedance by the third location, and the generation of unnecessary radiation from the first region or the second region can be effectively reduced. Is possible.

In the invention according to claim 10 , the third portion is not connected to the ground portion, and the third region is an odd number of 1/4 of the wavelength of the oscillation signal from the third location in the housing. It is characterized by being located in an area that is twice as far away.

In the invention according to claim 10 , the third region is not connected to the ground portion, and the third region is located in a region separated from the third location by an odd multiple of 1/4 of the wavelength of the oscillation signal. Since it is located, the first region or the second region having high impedance can be surely made low impedance by the third location, and the generation of unnecessary radiation from the first region or the second region is effectively reduced. It is possible to do.

The invention according to claim 11 is characterized in that an extension line connecting the housing and the third location is provided, and the third location is arranged at a position separated from the housing.

In the invention according to claim 11 , since the third portion is arranged at a position separated from the housing via an extension line, the first region or the second region where the impedance becomes high in the housing depending on the third location. It is possible to reliably reduce the impedance.

The invention according to claim 12 is characterized in that the housing is arranged in a predetermined region of the substrate, and the third portion is arranged in a predetermined region of the substrate.

In the invention according to claim 12 , even when the third location is arranged at a position away from the housing, the third location is arranged in a predetermined region of the substrate on which the housing is arranged, so that the substrate Even if other components of the tuner device, such as digital processing circuits and audio circuits, are placed close to each other on the side of the housing, the grounding point is not disturbed by these components. Can be placed away from the housing.

The invention according to claim 13 is characterized in that the range of the oscillation frequency of the oscillation signal is 2 GHz or more.

According to the thirteenth aspect of the present invention, the frequency range of the VCO used for receiving the television broadcast is included, and unnecessary radiation can be effectively reduced as a tuner device for receiving the television broadcast.

The invention according to claim 14 is characterized in that the signal processing unit is a tuner unit that receives a broadcast signal or a wireless communication unit that transmits and receives an information signal.

As described above, according to the tuner device of the present invention, the distance between two overlapping points of two regions having high impedance on the conductor line where the oscillation signal propagates through the housing is limited to a predetermined threshold value or less. In addition, the range in which unnecessary radiation is generated in the housing can be narrowed and eliminated, and unnecessary radiation can be effectively reduced.

FIG. 1 is a block diagram showing a circuit configuration of a tuner IC provided in the tuner device according to the first embodiment. FIG. 2 is a plan view showing a configuration of a main part of the tuner device in a state where a part of the housing is cut out. FIG. 3 is a side view showing a main configuration of the tuner device. FIG. 4 shows the state of generation of unnecessary radiation from the housing accommodating the tuner IC. FIG. 4A shows a case where two places are grounded, and FIG. 4B shows a case where three places are grounded. c) is a diagram exemplifying each of the cases where four points are grounded. FIG. 5 shows the state of generation of unnecessary radiation when the housing is grounded at three points. FIG. 5A shows the case where the oscillation frequency is 6 GHz, and FIG. 5B shows the case where the oscillation frequency is 7 GHz. FIG. 3C is a diagram illustrating each case where the oscillation frequency is 8 GHz. FIG. 6 shows the range of high impedance generated in the housing when the housing is grounded in two places, FIG. 6A shows the range of occurrence in a plan view, and FIG. 6B shows a developed view of the housing. The range of occurrence in is shown. FIG. 7 is a diagram showing a developed view of the housing. FIG. 8 (a) is a view of the main board to which the housing is attached from the back side, FIG. 8 (b) is a cross-sectional view around the grounded land provided on the main board, and FIG. 8 (c) is the non-grounded view. It is a cross-sectional view around the land of the state. FIG. 9 is a diagram showing a high impedance range in a state where the housing is unfolded when the front left corner portion and the rear right corner portion of the housing are grounded on the main board. FIG. 10 is a diagram showing a high impedance range in a state where the housing is unfolded when the front left corner portion and the right corner portion of the housing are grounded on the main board. FIG. 11A is a diagram showing a configuration in which the left corner portion on the front surface of the housing is grounded and the right corner portion on the rear surface is grounded across a line to narrow the high impedance range generated in the housing to one point. FIG. (B) is a diagram showing a specific example of a configuration in which the right corner portion of the rear surface is grounded to the grounding pattern of the main board via an extension line. FIG. 12A is a diagram showing the locus of the high impedance point C generated by the two grounding points, and FIG. 12B is a diagram in which the oscillation frequency is in the range of f1 ≦ f ≦ f2 on the locus of the high impedance point C. It is a figure which shows the high impedance range which occurs in the case. FIG. 13 shows variations in the distribution of the high impedance range that occur when the oscillation frequency is in the range of f1 ≤ f ≤ f2, and FIG. 13 (a) shows the distance between two high impedance points at the maximum frequency f2 at that frequency. The figure showing the case where the interval is larger than 1/10 of the frequency, the figure (b) shows the case where the interval between the two high impedance points is 1/10 or less of the frequency at that frequency, and the figure (c). ) Shows the case where the points having high impedance at the maximum frequency f2 overlap at one point, and the figure (d) shows the case where the points having high impedance at the frequency f4 lower than the maximum frequency f2 overlap at one point. The figure (e) shows the case where the distance between two points having high impedance at the lowest frequency f1 is 1/10 or less of the wavelength at that frequency, and the figure (f) shows the case where the lowest frequency f1. It is a figure which shows the case where only one point which becomes high impedance remains. FIG. 14 shows a second embodiment of the present invention, in which FIG. 14A is an extension line in which the left corner portion on the front surface is grounded and the right corner portion on the rear surface is arranged in the area of the main board located below the housing. A diagram showing how the high impedance range generated in the housing is narrowed to one point by grounding at a distance, and FIG. 3B is a diagram showing the state of the grounding pattern around the housing arrangement position of the main board. (C) is a diagram showing a specific configuration of an extension line arranged in the area of the main board located below the housing, and FIG. 3D is a cross-sectional view taken along the line DD of FIG. .. FIG. 15 shows a modified example of the line arranged in the area of the main board located below the housing, FIG. 15A shows an example in which the line has an arc shape, and FIG. 15B shows an arc shape. FIG. 6C is a diagram showing an example in which the shape is combined with the linear shape, and FIG. 3C is a diagram showing an example in which the shape is a wave shape. 16A and 16B show a second modification of the line, FIG. 16A is a plan view of a connection portion between the housing and the main board, FIG. 16B is a cross-sectional view, and FIG. 16C is a bottom view. Is. FIG. 17 shows a third modified example of the line, and is a perspective view in which the line is configured by using a metal wire. FIG. 18 shows a fourth modified example of the line, and is a cross-sectional view of a connecting portion between the housing and the main board when the line is configured by using a linear conductor and a wiring pattern. FIG. 19 shows a fifth modified example of the line, and is a cross-sectional view of a connecting portion between the housing and the main board when the line is configured by using a leaf spring-shaped conductor. FIG. 20 shows a third embodiment of the present invention, and is a diagram showing a configuration in which high impedance points generated in a housing are reduced in impedance. FIG. 21 shows a modified example of the same embodiment, and is a diagram showing an example in which all the grounding points of the housing to the main board are arranged at positions away from the housing. FIG. 22 shows a fourth embodiment of the present invention, and is a diagram showing a configuration that eliminates a high impedance range generated in a housing. FIG. 23 shows a fifth embodiment of the present invention, and is a diagram showing a configuration in which a high impedance range is not generated around the connector. FIG. 24 is an explanatory diagram considering only signal propagation centered on the top surface of the housing when the electrical connection between the side surfaces of the housing accommodating the tuner IC is weak. FIG. 25 (a) is a development view of the housing when the electrical connections between the side surfaces of the housing are strong, and FIG. 25 (b) shows the space between the side surfaces of the housing when the electrical connections between the side surfaces of the housing are strong. It is explanatory drawing which also considers signal propagation. FIG. 26 shows a sixth embodiment of the present invention, in which FIG. 26A is a view in which an open portion provided in a housing is arranged at a position away from the housing, and FIG. 26B is a configuration around the open portion. It is a figure which shows.

Hereinafter, embodiments of the present invention will be described.

(First Embodiment)
FIG. 1 shows a circuit diagram of a tuner IC included in the tuner device of the display device according to the first embodiment of the present invention. This tuner IC (tuner unit) is for, for example, television broadcasting, and its output broadcast signal is output to a display unit (not shown), and the display unit displays an image corresponding to the broadcast signal.

In the tuner IC 10 in the figure, 1 is an RF-amplifier (Gain Control Amplifire), 2 is an interstage filter, 3 is a VCO / PLL circuit, 4 is a 1 / N circuit, 5 is a mixer, 6 is a detector, and 7 is a stage. An inter-filter, 8 is an IF-amplifier (Gain Control Amplifire), and 9 is an AGC (Auto Gain Control) circuit.

The RF-amplifier 1 amplifies a received signal having an RF frequency of 90 to 767 MHz, which is, for example, a Japanese terrestrial television broadcasting frequency band, and the interstage filter 2 band-limits the amplified signal. The VCO / PLL circuit (oscillation unit) 3 generates an oscillation frequency in a frequency range of 2 GHz or more, for example, 6 to 8 GHz by changing the oscillation frequency of the oscillation signal output by the built-in local oscillator according to the tuning voltage of the PLL circuit. Let me. The 1 / N circuit 4 is obtained by multiplying the oscillation frequency generated by the VCO / PLL circuit 3 by 1 / N (N is, for example, 6 to 133) to obtain a local oscillation frequency of, for example, 96.5 to 770.5 MHz. Is. Further, the mixer 5 mixes the RF frequency received signal from the interstage filter 2 with the local oscillation frequency from the 1 / N circuit 4 to perform frequency conversion of the received signal. The detector 6 detects the difference voltage of the differential output from the mixer 5. The interstage filter 7 band-limits the differential output signal of the mixer 5 that has passed through the detector 6, and the IF-amplifier 8 amplifies the received signal after the band-limited frequency conversion, for example, 3. Outputs a signal with an IF frequency of .5 MHz. Further, the AGC circuit 9 is a gain control signal RF AGC that controls the amplification degree of the RF-amplifier 1 and the IF-amplifier 8 based on the difference voltage between the differential outputs of the mixer 5 detected by the detector 6. , IF AGC occurs.

As shown in FIG. 2, the tuner IC 10 having the above configuration is arranged on the main board (board) 20 together with the crystal oscillator 15, the capacitor, the inductor, and other chip components 16. The tuner IC 10, the crystal oscillator 15, and the chip component 16 are all shielded by a rectangular conductive housing 22 that covers them. The housing 22 is composed of a conductive frame or cover made of metal or non-metal plated. Therefore, the housing 22 is configured to suppress noise from being mixed into the tuner circuit such as the mixer 3 in the tuner IC 10 from the outside, and to reduce leakage and radiation of signals generated in the tuner circuit to the outside. Has been done.

The tuner IC 10 constitutes a signal processing unit that processes a signal having a frequency higher than a predetermined threshold value. Here, since the tuner IC 10 constitutes the signal processing unit in the present embodiment, the predetermined threshold value is 50 MHz when the bandwidth of the received RF signal is 50 MHz to 3.2 GHz.

Further, in the present embodiment, the signal processing unit is configured by the tuner IC10, but the present invention is not limited to this, and other signals are transmitted by wireless communication units such as wifi and bluetooth (registered trademark) that transmit and receive information signals. A processing unit may be configured. In this case, since the bandwidth of the RF signal of the wireless communication unit such as wifi and bluetooth (registered trademark) is 2.4 to 2.5 GHz or 5 to 6 GHz, the predetermined threshold value is approximately 2.4 GHz and is wireless. In the case of a communication oscillation signal, the frequency is the same as the tuner oscillation signal, so the predetermined threshold is approximately 2 GHz. As shown in FIG. 2, an F-type connector (connector portion) 23 is attached to the housing 22. Then, an RF cable (signal cable) 24 for transmitting a television broadcast frequency signal (RF signal) is connected to the F type connector 23, and the RF signal is input to the RF-amplifier 1 of FIG.

As shown in FIG. 3, in the housing 22, for example, leg portions 22a are arranged at two corner portions 22v and 22s, respectively, and these leg portions 22a are inserted into through holes 20a formed in the main board 20. Soldering 25 is applied, and the leg portion 22a is grounded to the conductive pattern (grounding pattern = ground portion) 20c of the grounding potential formed on the upper surface and the lower surface of the main board 20 through the through holes 20a of the main board 20.

The housing 22 accommodating the tuner IC 10 and the like and the main board 20 on which the housing 22 is arranged constitute a tuner device on the television broadcast receiving circuit of the present embodiment.

In the television broadcast receiving circuit, the housing 22 is arranged on the main board 20, and is further formed on a microcomputer, a memory, a power supply component, and a main board 20 that perform processing such as demodulating television broadcast waves. Noise countermeasure parts to prevent noise from being mixed into a large number of signal patterns, an external interface for connecting TV cables, etc. are arranged.

(Case dimensions)
For example, the dimensions of the housing 22 have a vertical length L = 17 mm, width W = 20 mm, height H = 10 mm, diagonal length D = 26.24 mm. Since the frequency of the oscillation signal generated by the VCO / PLL circuit 3 of the tuner IC 10 is 6 to 8 GHz, the minimum length at which the shielding effect against unnecessary radiation completely disappears in the housing 22, that is, the maximum oscillation of the oscillation signal. The half value (λ / 2) of the wavelength λ at the frequency (8 GHz) is 18.75 mm. Therefore, in the dimensions of the housing 22, the width W = 20 mm and the diagonal length D = 26.24 mm exceed the half wavelength (λ / 2), so that measures for reducing unnecessary radiation are required. Further, since the diameter size of the F type connector 23 is defined by the standard, when the housing 22 is grounded to the main board 20 by, for example, the two corner portions C1 and C2 shown in FIG. 2, both corner portions thereof. The distance between C1 and C2 is width W + 2 and height H = 37 mm, and even if the width W (= 20 mm) and the diagonal length D (= 26.24 mm) are the half wavelength (λ / 2 = 18.75 mm). Even if it can be reduced to the above, it is practically difficult to reduce unnecessary radiation in the housing 22.

The results of measurement by the present inventor of how unnecessary radiation is generated in the housing 22 as described above are shown in FIGS. 4 (a) to 4 (c). Unwanted radiation is high-frequency noise that is output to the outside from a device that processes high-frequency signals and is different from the signals originally used for external devices (broadcast signals, communication signals, etc.) and causes radio interference. That is. As used herein, "unwanted radiation" has this meaning. FIG. 4 shows the number of grounded points of the housing 22 to the main board 20 as corners when the oscillation frequency in the VCO / PLL circuit 3 is fixed to a predetermined value (6 GHz). (A) shows the dispersion, the radiation direction, and the peak intensity of the unnecessary radiation in the housing 22 when the number of places is 2 in the figure (b), 3 in the figure (b), and 4 in the figure (c). As can be seen from these figures, the case where the number of grounding points in FIG. 3B is three is the least unnecessary radiation, but it is generated.

FIG. 5 shows how unnecessary radiation is generated when the oscillation frequency in the VCO / PLL circuit 3 is changed when there are three grounding points in FIG. 4 (b) where the unnecessary radiation is small. The figure (a) shows an example in which the oscillation frequency is set to 6 GHz, the figure (b) shows a case where the oscillation frequency is set to 7 GHz, and the figure (c) shows a case where the oscillation frequency is set to 8 GHz. As can be seen from the figure, when the oscillation frequency is changed even at the same three grounding points, the dispersion, radiation direction, and peak intensity of unnecessary radiation change, respectively, and the peak intensity of unnecessary radiation at the maximum oscillation frequency (= 8 GHz). Is the highest.

Therefore, it is usually extremely difficult to specifically specify the grounding point of the housing 22 that can reduce unnecessary radiation below the standard over the entire variable range of the oscillation frequency in the VCO / PLL circuit 3.

(Characteristic points of this embodiment)
In the present embodiment, even when any of the various dimensions of the housing 22 cannot be set to less than half a wavelength (λ / 2) at the maximum oscillation frequency (8 GHz) as described above, unnecessary radiation is easily and effectively ensured. Adopt a configuration that reduces the frequency. Hereinafter, a detailed description will be given.

(Designation of candidates for grounding points)
First, a candidate for a grounding point is arbitrarily specified. In the present embodiment, this grounding point is defined as a case where the number of grounding points shown in FIG. 4A is small, that is, a case where two points, a front left corner portion and a rear right corner portion, are designated as grounding points in the same figure. It will be described by way of example. The designated portion may be another corner portion, or may be three or four locations as shown in FIGS. 4 (b) and 4 (c).

As described above, FIGS. 6A and 6B show a range in which the housing 22 has a high impedance when the grounding points are the front left corner portion and the rear right corner portion of the housing 22.

The housing 22 is formed into a quadrangular prism shape by processing one metal plate. FIG. 7 shows an unfolded view of the housing 22, and the four side surfaces b to e are folded with respect to the top surface a to create a square housing 22. At this time, on the front surface b and the rear surface d on which the mounting holes 23a for the F type connector 23 are formed, the legs 22h and 22i extending downward for grounding to the main board 20 are formed at both lower corners thereof, respectively. 22j and 22k are formed, and square holes 22l, 22m, 22n and 22o are formed at positions above the legs 22h to 22k, respectively. On the other hand, on the two side surfaces c and e that are in contact with the front surface b and the rear surface d at the time of folding, the protrusions 22c that are fitted into the holes 22l to 22o formed in the front surface b and the rear surface d at both lower corners thereof, respectively. 22e, 22f, 22g are formed. Then, the housing 22 is connected to the grounding pattern 20c of the main board 20 in the assembled state in which one metal plate is folded.

On the other hand, the main board 20 is configured as follows. FIG. 8A shows a state in which the main board 20 on which the housing 22 is arranged is viewed from the back surface. In the main board 20 shown in the figure, lands 20e to 20h are formed at positions corresponding to the four corners of the housing 22. The lands 20e and 20g corresponding to the two corners 22r and 22s of the housing 22 as the grounding points are connected to the grounding pattern 20c arranged on the back surface of the main board 20, and the other two lands 20f and 20h are grounded. It is not connected to the pattern 20c. In the figure (a), reference numeral 20d is a land for connecting the F type connector 23 to a signal pattern (not shown) on the main board 20.

As shown in FIGS. (B) and (c), through holes 20s are formed in the four lands 20e to 20h of the main board 20 at positions corresponding to the four corners of the housing 22. Then, in the lands 20e and 20g corresponding to the two corner portions 22r and 22s as the grounding points of the housing 22, the through holes 20s are at least one of the front surface and the back surface of the main board 20 as shown in FIG. In the lands 20f and 20h corresponding to the other two non-grounded corners 22t and 22u of the housing 22 which are connected to the grounding pattern 20c arranged in the above, the through holes 20s have the grounding pattern 20c as shown in FIG. Not connected to.

Then, as shown in FIG. 8A, of the legs 22h to 22k of the front surface b and the rear surface d of the housing 22, the legs 22h of the left corner portion 22r of the front surface b to be grounded and the right corner portion of the rear surface d. With the legs 22k of 22s inserted into the through holes 20s of the main board 20, the through holes 20s and the legs 22h and 22k are soldered 25, and these legs 22h and 22k are grounded to the main board 20. It is connected to the pattern 20c.

On the other hand, in the two non-grounded corners 22t and 22u of the housing 22, the through holes 20s have the legs 22i and 22j inserted into the through holes 20s of the main board 20 as well as the grounded corners 22r and 22s. And the legs 22i and 22j are soldered 25 to fix the two ungrounded corners 22t and 22u of the housing 22 to the lands 20f and 20h of the main board 20, but they are not connected to the grounding pattern 20c. It is supposed to be.

From the above configuration, in the present embodiment, due to the configuration of the housing 22 shown in FIG. 7, when one metal plate is folded to assemble the hollow square housing 22, the lower angle of the left side surface e thereof. The upper corner portion 22q of the portion 22p and the right side surface c has a low degree of ground contact due to the mechanical engagement between the protrusions 22c and 22f of FIG. 7 and the holes 22l and 22o. When the lower left corner portion 22r on the front surface and the lower right corner portion 22s on the rear surface of the housing 22 are grounded as shown in FIG. The right corner portion 22s of the above becomes the grounding potential, and the grounding effect at both corner portions 22p and 22q having a low degree of grounding is ignored.

(Specification of high impedance range in the housing)
As described above, when the maximum frequency of the oscillation signal in the VCO / PLL circuit 3 is 8 GHz and its wavelength λ is shortened to about 40 mm, it oscillates when the size of the housing 22 exceeds the half wavelength (λ / 2). In the housing 22 which is the signal propagation path, the impedance becomes a distribution constant. In this distributed constant circuit, the grounded portion is used as the reference impedance, and the portion separated by an odd multiple of λ / 4 from the grounded portion is an open end and has a high impedance. When a plurality of grounding points are provided, the overlapping portion at an odd multiple of λ / 4 from the grounding points has the highest impedance.

Specifically, on the developed view of the housing 22 shown in FIG. 6B, as described above, the ground potential is located at two points, the left corner portion 22r of the front surface b and the right corner portion 22s of the rear surface d. Therefore, the highest impedance is obtained at a position that is an odd multiple of λ / 4 at both of these two grounding points 22r and 22s. In the figure, the high impedance range A in which the high impedance portion λ / 4 away from the left corner portion 22r of the front surface b and the high impedance portion λ / 4 away from the right corner portion 22s of the rear surface d overlap, and the rear surface d. A range B is drawn in which a high impedance portion λ / 4 away from the right corner portion 22s and a high impedance portion 3 times λ / 4 away from the left corner portion 22r of the front surface b overlap. In this way, when the left corner portion 22r of the front surface b and the right corner portion 22s of the rear surface d are set to the ground potential on the developed view of the housing 22, the high impedance ranges A and B are the front surface b, the rear surface d, and the ceiling. It occurs in the lower left corner and the upper right corner of the surface a. In the two high impedance ranges A and B, the points shown by white circles are when the frequencies of the oscillation signals of the VCO / PLL circuit 3 are 6 GHz, 6.5 GHz, 6.8 GHz and 6.9 GHz. A high impedance point λ / 4 away from the left corner 22r of the front surface b and 3 times λ / 4 away from the right corner 22s of the rear surface d, and λ / 4 away from the right corner 22s of the rear surface d and the front surface b. It shows a high impedance point 3 times as large as λ / 4 from the left corner portion 22r of.

Therefore, in the developed view of FIG. 6B, a large amount of unnecessary radiation is generated in the two high impedance ranges A and B.

In addition, in FIGS. 6A and 6B, the high impedance ranges A and B that occur when the housing 22 is assembled by folding the metal plate shown in FIG. 7 are shown. For example, the metal plate shown in FIG. 7 is shown. After assembling, the parts where the front surface b and the rear surface d are in contact with the right side surface c and the left side surface e are firmly joined by soldering to increase the degree of ground contact. The lower corner portion 22p of e has the same potential as the left corner portion 22r of the front surface b, and the upper corner portion 22q of the right side surface c has the same potential as the right corner portion 22s of the rear surface d. There are four grounding points on the figure. In this case, the generated high impedance ranges C and D are generated in the lower left corner portion and the upper right corner portion of the top surface a, and large unnecessary radiation is generated from these ranges C and D.

FIG. 10 shows a state in which the left corner portion 22r and the right corner portion 22v of the front surface b are grounded when the housing 22 is created using the metal plate shown in FIG. In the figure, the generated high impedance ranges E and F are generated in the upper center of the front surface b and the upper center of the rear surface d, and large unnecessary radiation is generated from these ranges C and D. In the case of the main grounding, the area of the high impedance range is smaller than that in the case of the grounding shown in FIG. 6 and the case of the grounding shown in FIG. 9, but the occurrence occurs.

(Reduction of high impedance range of housing)
As described above, the housing 22 has a high impedance range, and the position and area of this high impedance range change according to the grounding point of the housing 22. In this embodiment, a configuration that reliably reduces this high impedance range is adopted. This will be described in detail below.

FIG. 11A shows the case of the ground contact state of FIG. 6B, that is, the left corner portion 22r of the front surface b and the right corner portion 22s of the rear surface d on the developed view of the housing 22 of FIG. 6B. The configuration for grounding the main board 20 to the grounding pattern 20c is modified to reduce the high impedance range generated in the housing.

In the figure, the high impedance range B (see FIG. 6) generated on the developed view of the housing 22 is reduced. As described above, in the housing 22 in which the oscillation frequency of the oscillating unit is high and the impedance is a distribution constant, a predetermined impedance determined in advance is set at a position that is an odd multiple of λ / 4 from the grounded portion with the grounded portion as the reference impedance. Higher impedance than. Therefore, on the developed view of the housing 22 shown in FIG. 6B, a region separated from the left corner portion 22r of the front surface b by a linear distance of 3 times λ / 4 and λ / from the right corner portion 22s of the rear surface d. The high impedance range B is a range that overlaps with a region that is one times as far away as 4.

In the present embodiment, as can be seen from FIG. 11A, the left corner portion (first location) 22r of the front surface b is grounded, and one end of the extension line L is connected to the right corner portion 22g of the rear surface d to extend the extension line L. A configuration is adopted in which the other end (second location) of the wire L is used as the grounding portion 22w and the housing 22 is connected to the grounding pattern 20c of the main board 20.

FIG. 11B shows a specific example of a configuration in which the right corner portion 22g of the rear surface d is grounded to the grounding pattern 20c of the main board 20 via the extension line L.

In FIG. 3B, the leg portion 22n provided at the right corner of the rear surface d of the housing 22 is inserted into the through hole 20s of the land 20 g in the non-grounded state provided on the main board 20, and after soldering 25, it is performed. One end of the metal line 35 is connected to the soldered portion 25 as the extension line L, and the other end of the metal line 35 is connected to the grounding pattern 20c arranged on the back surface of the main board 20.

In the present embodiment, on the developed view of the housing 22 of FIG. 11A, the lowest frequency in the variable frequency range of the oscillation signal of the VCO / PLL circuit 3 from the left corner portion (first location) 22r of the front surface b (the same). In the figure, among the points at a distance of 3 times the wavelength λ at 6 GHz) (points within the high impedance range B shown in FIG. 6 (b)), the point closest to the right corner portion 22 g of the rear surface d. Let be a point P, the total of the distance from this point P to the land 20g at the right corner of the rear surface d of the housing 22 and the distance from this land 20g to the ground contact point 22w (that is, the line length of the extension line L). The line length of the extension line L is set so that the distance corresponds to 1/4 of the wavelength λ at the lowest frequency (6 GHz) of the variable frequency range of the oscillation signal. That is, a region (this region (first location)) that is 3/4 of the wavelength λ in the variable frequency range of the oscillation signal of the VCO / PLL circuit 3 from the left corner portion (first location) 22r of the front surface b of the housing 22. 1 region) is shown by a thick solid line in FIG. 11A) and a region (this region) that is 1/4 of the wavelength λ in the variable frequency range from the grounding location (second location) 22w. The line length of the extension line L is set so that the region (second region) is shown by a thick broken line in FIG. 3A) at one point of the point P.

Since the extension line L is an aerial wiring in this embodiment, the wavelength shortening according to the dielectric constant does not occur. Therefore, for the calculation of the distance to the high impedance point P, the actual size of the line length of the extension line L may be used.

Therefore, in the present embodiment, the high impedance range generated in the housing 22 is only the high impedance point P generated at the lowest frequency (6 GHz) at which the wavelength λ of the oscillation signal is the longest, so that the high impedance range generated is the narrowest. Become. Therefore, in the present embodiment, unnecessary radiation generated from the housing 22 can be effectively reduced.

In the present embodiment, the case where the high impedance range is reduced to only one point of the high impedance point P is illustrated, but the present invention is not limited to this, and for example, the line length of the extension line L is set to the above line length. Of course, even if the high impedance range is set to be shorter than that and the high impedance range is slightly widened, the same can be applied as long as the high impedance range B is reduced as shown in FIG.

<Generalized model that reduces the high impedance range>
Next, a case where the conventional high impedance range B is reduced will be described using a generalized model.

In FIG. 12A, points A and B are grounding points and are arranged at a distance l from each other. Further, the point C is a point separated from the points A and B by nλ / 4 and mλ / 4, respectively. As described above, if the integers n and m are odd, the point C represents a high impedance point.

If the coordinates of points A, B, and C are (x _a , y _a ) = (0,0), (x _b , y _b ) = (0, l), (x _c , y _c ), the following equation is To establish.

nλ / 4 ＝ √ (x _c ² + y _c ² ), mλ / 4 ＝ √ {x _c ² + (ly _c ) ² }
∴ m ² (x _c ² + y _c ² ) ＝ n ² {x _c ² + (ly _c ) ² }
When m = n, y _c = l / 2
When m> n, x _c ² + {y _c --n ² l / (m ² --n ² )} ² = {n ² l / (m ² --n ² )} ²
Therefore, when the wavelength λ is changed, the locus of point C becomes the median of AB when m = n, and the center (0, −n ² l / (m ² − n ² )) when m> n. , Draw an arc with a radius of ml / (m ² -n ^2).

If the oscillation frequency is f1 ≤ f ≤ f2, the wavelength λ = c / f is in the range λ2 ≤ λ ≤ λ1 (in the case of an arc, the range drawn by the thick line in FIG. 12B), and unnecessary radiation is generated. The target high impedance range is the range of λ2 ≦ λ ≦ λ1 on the middle line AB or the arc (in the case of the arc, the range drawn by the thick line in FIG. 12B).

If the high impedance range that is the target of unwanted radiation shown in FIG. 12B can be narrowed as much as possible, the range of influence of unwanted radiation can be suppressed. Further, if the high impedance range that is the target of unnecessary radiation is narrowly suppressed, it is possible to completely eliminate unnecessary radiation by applying other impedance reducing means to this narrow high impedance range.

Here, since the impedance can usually be suppressed low in the range from the grounding point to the distance λ / 20, the plurality of grounding points provided on the housing or the substrate, which are not particularly limited in cost or shape, are λ / 10, respectively. It is often designed at intervals of, and the intermediate position between those grounding points is set to be exactly the distance λ / 20 from the grounding point.

From this, also in the present invention, if the distance between the two regions having high impedance can be kept within the range of the width λ / 10 (second threshold value), the entire region having high impedance is limited to a narrow range. Is possible. Specifically, it will be described in detail with reference to FIG. 12 (b). In FIG. 12B, for example, when the oscillation frequency f of the VCO / PLL circuit 3 is the lowest frequency f1, a region on a circle having a radius of 1/4 of nλ1 centered on the grounding point A (first location) ( The first region) (this region is shown by a thick solid line in the figure) and the region on a circle with a radius of 1/4 of mλ1 centered on the other grounding point B (second location) (second region) ( It is desirable that this region (shown by a solid line in the figure) overlaps at two points, and the distance D1 between these two points is within the range of 1/10 (second threshold value) of the width λ1. Similarly, when the oscillation frequency f of the VCO / PLL circuit 3 is the highest frequency f2, a region (first region) on a circle having a radius of 1/4 of nλ2 centered on the grounding point A (first location) (1st region). This region is shown by a thick broken line in the figure) and the region on a circle with a radius of mλ2 centered on the other grounding point B (second location) (second region) (this region is shown in the same figure). (Indicated by the middle broken line) overlaps at two points, and the distance D2 between these two points is shorter than the distance D1 between the two points at the lowest frequency f1 (D2 <D1). Variations in the distribution of the high impedance range that can occur depending on the distance between B and the frequency that is the target of unnecessary radiation will be described with reference to FIGS. 13 (a) to 13 (f).

<Variation of distribution in high impedance range>
FIG. 13A shows a case where the distance between two points having high impedance at the highest frequency f2, which is the target of unnecessary radiation, is larger than 1/10 of the wavelength λ2 at this frequency. Here, each of the two high impedance ranges includes the entire frequency range and is the widest state. Moreover, since the two high impedance ranges are distributed at intervals larger than 1/10 of the wavelength λ2, even if other impedance reducing means including the method described later are used in combination, both high impedance ranges are lowered at the same time. It is difficult to make it impedance.

In FIG. 13B, the distance between two points having high impedance at the highest frequency f2, which is the target of unnecessary radiation, is 1/10 or less of the wavelength λ2 at this frequency. As a result, although each of the two high impedance ranges includes the entire frequency range, for example, the midpoint of the line segment connecting the two points having high impedance at the maximum frequency f2 is set as D, and the position of this point D is set. By using an impedance reducing means to reduce the impedance, it is possible to sufficiently reduce the impedance within a range separated from the point D by a distance of λ / 20 within the two high impedance ranges. Further, if the distance between the two points having high impedance is further narrowed, the frequency range in which the distance is λ / 20 or less from the point D increases, so that the frequency range in which the impedance is lowered within the two high impedance ranges is increased. Will increase. In the case of FIG. 13B, since the separation between the two high impedance regions is 1/10 or less of the wavelength λ2, the entire high impedance range is narrowed as surrounded by a broken line in the figure. Can be restricted. Therefore, it is possible to reduce the impedance by using other impedance reducing means aiming at the high impedance range in a narrow region as a whole in this way. Easy to design.

In FIG. 13 (c), the points having high impedance at the highest frequency f2, which is the target of unnecessary radiation, overlap at one point. At this time, the frequency at which the distance between the two points having high impedance coincides with 1/10 of the wavelength λ of that frequency is represented by f3 in the figure. Here, the midpoint of the line segment connecting two points where f1 <f3 <f2 and high impedance at the frequency f3 is set as D, and this point D is set in combination with other impedance reducing means including the method described later. By lowering the impedance, the impedance can be sufficiently lowered in the frequencies f3 to f2 in each of the two high impedance ranges. In FIG. 13 (c), as shown by being surrounded by a broken line, the entire range of high impedance can be limited to a narrower region as compared with the case of FIG. 13 (b), so that the high impedance range of this narrow region is low. Impedance design becomes even easier.

In FIG. 13D, a point where high impedance is obtained at a frequency f4 lower than the maximum frequency f2, which is the target of unnecessary radiation, overlaps at one point. At this time, the frequency at which the distance between the two points having high impedance coincides with 1/10 of the wavelength of that frequency is lower than the frequency f3 in FIG. 13 (c) (f5). It is expressed as <f3)). Here, f1 <f5 <f4 <f2, and even if the point D is not lowered in impedance, there is no point where the impedance becomes high at a frequency higher than the frequency f4, and the impedance is high at the frequency f5. The middle point of the line segment connecting the two impedance points is set as D, and by using other impedance reducing means including the method described later in combination to lower the impedance of this point D, the high impedance range f1 to f4 is ranged. Even within, the impedance can be sufficiently lowered in the frequency range of f5 to f4.

In FIG. 13 (e), the distance between two points having high impedance at the lowest frequency f1 that is the target of unnecessary radiation is 1/10 or less of the wavelength λ1 at this frequency. In this case, f1 <f4 <f2, and even if the point D is not made low impedance, there is no point that becomes high impedance at a frequency higher than the frequency f4, and high impedance is obtained at the lowest frequency f1. The midpoint of the line segment connecting these two points is set as the point D, and the impedance is lowered sufficiently by using other impedance reducing means including the method described later to sufficiently lower the impedance in the entire frequency range f1 to f2. Is possible.

In FIG. 13 (f), only one point (point D) that has high impedance at the lowest frequency f1 that is the target of unnecessary radiation remains, and this point is used in combination with other impedance reducing means including the method described later. By lowering the impedance of D, the impedance can be completely lowered in the entire frequency range f1 to f2.

As described above, in order to narrow the high impedance range, at least the distance between two points having high impedance at the maximum frequency f2, which is the target of unnecessary radiation, is 1/10 of the wavelength at that frequency (FIG. 13 (b)). ~ (F)), and if possible, the distance between two points that have high impedance at the lowest frequency f1 is 1 / of the wavelength at that frequency so that the entire oscillation frequency range can be lowered. It is desirable that the frequency is 10 or less (FIGS. 13 (e) and 13 (f)).

(Second Embodiment)
14 (a) to 14 (d) show the second embodiment of the present invention. In the first embodiment, the grounding portion 22w at the corner (land) 20g is arranged outside the housing 22, but in the present embodiment, the grounding portion is located in the area of the main board 20 where the housing 22 is arranged. It is arranged in a predetermined area (hereinafter referred to as a predetermined area).

In FIG. 6A, an extension line L extends from the land 20g at the corner of the rear surface d of the housing 22 toward a predetermined area of the main board 20 located below the housing 22, and the end of the extension line L extends. Is grounded as a grounding point 22w'.

Specific examples of this are shown in FIGS. (B) and (c). In FIGS. (B) and (c), the legs 22n provided at the right corner of the rear surface d of the housing 22 are soldered 25 to the land 20g of the main board 20. For example, a copper foil constituting the grounding pattern 20c is cut out around the land 20g of the main board 20, and as the extension line L from the land 20g toward a predetermined area of the main board 20 below the housing 22. The copper foil is cut out so that the wiring pattern of 20 m is formed. Therefore, the leg portion 22n of the housing 22 is connected to the grounding pattern 20c via a linear wiring pattern 20m, and the connection point between the wiring pattern 20m and the grounding pattern 20c connects to the second grounding point 22w'. Configure.

The length of the wiring pattern 20 m is determined as follows. In the present embodiment, since the wiring pattern 20 m is arranged on the main board 20, the wavelength λ'of the oscillation signal on the main board 20 is 1 of the wavelength λ in vacuum due to the relative permittivity er of the main board 20. It is shortened to / (er ^1/2). For example, when the distance from the position of the high impedance point P of the housing 22 to the right corner portion 20g of the rear surface d of the housing 22 is 90% of the wavelength λ in the air, which is 1/4 times. The line length of the wiring pattern 20 m may be a distance of 10%, which is 1/4 times the wavelength λ'at the relative permittivity er. Specifically, assuming that the relative permittivity er of the main board 20 is er = 4 and the oscillation frequency f of the oscillation signal is f = 6 GHz, the wavelength λ'at the relative permittivity er is
λ'= (1 / (er ^1/2 )) λ = (1/2) x (c / f)
c: Speed of light = (1/2) x (3 x 10 ⁸ / (6 x 10 ⁹ )) = 0.025 m = 25.00 mm
Therefore, the line length is 25.00 × (1/4) × 0.1 = 0.625 mm ≈ 0.6 mm.
Can be calculated.

FIG. 2D is a cross-sectional view taken along the line DD at the location of the wiring pattern 20 m in FIG. When the characteristic impedance of the extension line L (wiring pattern 20 m) on the main board 20 is set to 75 Ω according to the general design specifications of the tuner device for television broadcasting, for example, the relative permittivity er of the main board 20 is set. Assuming that er = 4, the height h is h = 400um, and the thickness t of the wiring pattern 20m is t = 35um, the width s of the wiring pattern 20m and the cutout width of the copper foil (wiring pattern 20m and grounding pattern 20c) If the separation) w is calculated using a general line impedance design tool, the width s of the wiring pattern 20 m and the cutout width w of the copper foil are both calculated and determined as s = w = 200 um. It is not necessary to set the characteristic impedance of the extension line L on the main board 20 to 75Ω, and it is of course possible to set it to, for example, several tens to several hundreds of Ω.

Therefore, in the present embodiment, since the second grounding point 22w'is arranged in a predetermined area of the main board 20 below the housing 22, a microcomputer, a memory, or the like is arranged in the vicinity of the outside of the housing 22. Even in such a case, it is possible to satisfactorily arrange the second grounding portion 22w'from the housing 22 by the length of the wiring pattern 20m without being disturbed by these devices.

(Modification example of extension line)
FIG. 15 shows a first modification of the extension line L extending from the corner of the housing 22. In the above embodiment, instead of the extension line L having a linear shape, in the figure (a), the extension line L2 formed in an arc shape extending around 20 g of the land is used. Further, in FIG. 3B, an extension line L3 formed in combination with an arc shape extending around the land 20g and a linear shape extending from the tip thereof toward a predetermined area of the main board 20 below the housing 22. In the figure (c), it is an extension line L4 formed in a wave shape extending from the land 20 g. In these modified examples, since it is possible to ground at a position close to the land 20 g, interference with other wiring of the tuner circuit is avoided, and the grounding effect is reduced due to the large division of the grounding pattern. The effect of being able to prevent this occurs.

FIG. 16 shows a second modification of the extension line L. In the figure, the line length is adjusted by using the through holes formed in the main board 20.

Specifically, as shown in FIG. 6A, a wiring pattern 20q extending from the ungrounded land 20g toward a predetermined region of the main board 20 below the housing 22, and as shown in FIG. As shown in FIGS. (B) and (c), the through hole 20t formed at the tip of the wiring pattern 20q is connected to the lower end of the through hole 20t and formed on the lower surface of the main board 20. The extension line L5 is formed by the grounding pattern 20c. Therefore, in this modification, the line length of the extension line L5 is the total length of the extension pattern 20q and the height of the through hole 20t.

In the above-described embodiment and the first and second modifications, the extension lines L2 to L5 use the wiring pattern formed on the main board 20, so that the extension lines do not require other members such as metal wires. It is possible to easily configure L to L5.

FIG. 17 shows a third modification of the extension line L. In the figure, a metal wire L5 is used, one end thereof is soldered 25 with a land 20g, the other end is connected to the grounding pattern 20c of the main board 20, and the connection point is a grounding point 22w'.

FIG. 18 shows a fourth modification of the extension line L. In the figure, a linear conductor L6 such as a metal wire is used as the extension line L. Specifically, a wiring pattern 20q connected to the land 20g located at the corner of the housing 22 is formed on the upper surface of the main board 20, and a through hole 20o connected to the wiring pattern 20q and its side. The other through holes 20p arranged in the above are provided, and one end and the other end of the linear conductor L6 bent in an inverted U shape are inserted into the two through holes 20o and 20p to perform soldering 25. The lower end of the other through hole 20p is connected to the grounding pattern 20c formed on the lower surface of the main board 20.

Therefore, in the fourth modification, it is possible to adjust the distance between the corner portion 20g of the housing 22 and the ground contact portion 20w'by simply adjusting the wiring pattern 20q and the length of the linear conductor L6. ..

FIG. 19 shows a fifth modification of the extension line L. In the figure, a through hole 20o is formed on the side of the land 20g located at the corner of the housing 22, one end of the leaf spring-shaped conductor L7 is inserted into the through hole 20o, and the other end is the housing 22. One end of the conductor L7 is soldered to the through hole 20o while being in contact with the side surface, and the lower end portion of the through hole 20o is connected to the grounding pattern 20c formed on the lower surface of the main board 20.

Therefore, in this modification, it is possible to adjust the distance between the corner portion 20g of the housing 22 and the ground contact portion 22w'by simply adjusting the length of the leaf spring-shaped conductor L7.

In each of the various modifications of the extension line L described above, the length of the extension line L can be freely set to be long or short, regardless of the oscillation frequency range of the oscillation signal of the VCO / PLL circuit 3. It is possible to accurately set the distance from the high impedance point P of the housing 22 to the grounding point 22w to an odd multiple of 1/4 of the wavelength λ.

(Third Embodiment)
Subsequently, a third embodiment of the present invention will be described with reference to FIG.

In the first embodiment, as shown in FIG. 11, a high impedance point P is generated in the housing 22, but in the present embodiment, this high impedance point P is reduced in impedance.

In the present embodiment, in FIG. 20, in addition to the configuration of FIG. 11, another grounding point (third place) 22s is arranged on the lower side portion k of the left side surface e on the developed view of the housing 22. As described above, in the housing 22 in which the oscillation frequency of the oscillating unit is high and the impedance is a distribution constant, the impedance is higher than the predetermined impedance in a region separated by an odd multiple of λ / 4 with the grounded portion as the reference impedance. On the other hand, in a region (third region) separated by an even multiple of 1/4 of the wavelength λ of the oscillation signal, the impedance is lower than the predetermined impedance (predetermined threshold). Therefore, in FIG. 20, with respect to the high impedance point (point at the lowest oscillation frequency of 6 GHz) P on the developed view of the housing 22, this oscillation frequency (6 GHz) on the developed view of the housing 22 from this point P. The ground contact point 22s is arranged at a position separated by a linear distance by a distance of 1/2 (twice 1/4) the wavelength λ at).

Therefore, in the present embodiment, the high impedance point P generated on the developed view of the housing 22 can be made low impedance by another grounding point 22s. As a result, unnecessary radiation from the high impedance point P generated by the two grounding points (first and second points) 22r and 22w can be effectively reduced by the other grounding points (third point) 22s. It is possible.

Further, as in the above embodiment, this embodiment is effective even when the high impedance range is slightly widened.

That is, in FIGS. 13 (b) to 13 (f), the midpoint of the line connecting the two high impedance points at the lowest oscillation frequency in which the distance between the two high impedance points is within 1/10 of the wavelength of that frequency. From (Point D), the high impedance range can be effectively lowered by providing a grounding point at a position separated by a linear distance by an even multiple of 1/4 of the wavelength λ at this oscillation frequency. can.

(Modification example)
FIG. 21 shows a modified example of this embodiment.

In the third embodiment, the housing 22 is grounded at a position separated from the right corner portion of the rear surface d by the extension line L as a grounding portion 22w. It is grounded at the grounding points 22j and 22z separated from both the land 22s provided on the lower side portion k of the left side surface e and the extension lines R1 and R2, respectively.

In this modification, even if the minimum frequency of the oscillation signal of the VCO / PLL circuit 3 is lower than 6 GHz or the size of the housing 22 is relatively small, there are three grounding points away from the housing 22. Since the mutual distance between 22j, 22w, and 22z can be freely adjusted, the high impedance point P can be more reliably and easily lowered in impedance.

(Fourth Embodiment)
Subsequently, a fourth embodiment of the present invention will be described with reference to FIG.

In the first embodiment, the grounding portion is arranged in the housing 22 at a position where only the high impedance point P is generated, but in the present embodiment, the grounding portion is arranged at a position where the generated high impedance range is eliminated. ..

That is, in FIG. 11 of the first embodiment, the left corner portion 22r of the front surface b of the housing 22 is three times the wavelength λ at the lowest frequency (6 GHz) of the oscillation signal of the VCO / PLL circuit 3. The position P at a distance and the position P at a distance of 1/4 of the wavelength λ at the lowest frequency (6 GHz) from the ground contact point 22w separated by the extension line L from the right corner portion 20 g of the rear surface d. The overlapping positions P became high impedance, but in the present embodiment, the high impedance point is provided by arranging the extension line R in which the line length of the extension line L is set longer than that in the case of FIG. It is configured to eliminate the occurrence of P.

With the above configuration, in the present embodiment, the other end of the extension line R having a long line length is set as the grounding point 22x, and the distance M from the grounding point 22x to the high impedance point P is the wavelength at the lowest frequency (6 GHz). Since the distance can be more than 1/4 of λ, the occurrence of the high impedance point P can be eliminated, and the effect that unnecessary radiation is not generated anywhere in the housing 22 can be obtained.

Further, when the distance M is an even multiple (for example, 1/2) of 1/4 of the wavelength λ, the high impedance point P can be directly set to low impedance.

(Fifth Embodiment)
FIG. 23 shows a fifth embodiment of the present invention.

In the present embodiment, as shown in FIG. 23, the position separated from the left corner portion 22r of the front surface b of the housing 22 by the extension line Y is set as the grounding point 22y, and the right corner portion 22v of the front surface b is used as the grounding point. There is.

With the above configuration, in the present embodiment, it is possible to eliminate overlapping points at a distance of 1/4 and 3 times the wavelength λ of the oscillation signal of the VCO / PLL circuit 3 from the grounded points 22y and 22v. ..

Therefore, as shown in FIG. 10, the high impedance ranges E and F at the upper center portion of the front surface b and the upper center portion of the rear surface d, which occur when both corner portions 22r and 22v are grounded, are eliminated. , It is possible to eliminate the generation of unnecessary radiation.

Moreover, a signal cable 24 for television broadcasting is connected to the F type connector 23 attached to the mounting hole 23a on the front surface b of the housing 22, and in the vicinity of the signal cable 24, the front surface of the housing is shown in FIG. Although a high impedance range E is generated in the upper center portion of b, in the present embodiment, the occurrence of this high impedance range E is eliminated, so that the impedance distribution on the housing is the state (type, material, It is less susceptible to variations in shape, etc.), and has the effect of suppressing the generation of unnecessary radiation due to variations in the state of the signal cable.

In the present embodiment, the high impedance range E generated in the vicinity of the F type connector 23 is eliminated, but the present invention is not limited to this. For example, even if a high impedance range is generated in the housing 22, the height thereof is high. As the influence of unnecessary radiation generated from the impedance range is less or less, it is sufficient that the generated high impedance range is located at a distance of a predetermined distance or more from the F type connector 23. Further, when the distance from the grounding point 22y to the F type connector 23 is an even multiple (for example, 1/2) of 1/4 of the wavelength λ, the vicinity of the F type connector 23 can be directly set to low impedance.

In the fourth and fifth embodiments, only one of the two corners is grounded with the extension line R or Y separated, but all the corners to be grounded may be grounded with the extension line separated. Of course it is good.
(Sixth Embodiment)
Subsequently, a sixth embodiment of the present invention will be described with reference to FIG.

In the first embodiment (FIG. 11), on the developed view of the housing 22, the grounding point 22w is grounded from the right corner portion 22g of the rear surface d via the extension line L, but in the present embodiment, the grounding point 22w is grounded. Is not grounded, but is an open location, and the length of the extension line L is changed.

Specifically, in the present embodiment, on the developed view of the housing 22 of FIG. 26A, one end of the extension line is connected to the right corner portion 22g of the rear surface d, and the other end of the extension line L (housing 22). The other end of the extension line L is the open portion 22 op of the housing 22.

Then, on the developed view of the housing 22, 3 of 1/4 of the wavelength λ at the lowest frequency (6 GHz in the figure) of the variable frequency range of the oscillation signal of the VCO / PLL circuit 3 from the left corner portion 22r of the front surface b. The point closest to the right corner 22g of the rear surface d among the points of the doubled distance (points in the high impedance range B shown in FIG. 6B) is defined as the point P, and the point P to the rear surface d of the housing 22. The total distance between the distance to the land 20g at the right corner of the oscillating signal and the distance from the land 20g to the open portion 22op (that is, the line length of the extension line L) is the lowest frequency (6GHz) in the variable frequency range of the oscillation signal. The line length of the extension line L is set so as to correspond to an even multiple (2 times) value (= λ / 2) of 1/4 of the wavelength λ at.

Therefore, in the present embodiment, in the housing 22, a region separated by an odd multiple (3 times) of λ / 4 by a linear distance on the developed view from the grounded portion of the left corner portion 22r of the front surface b as a reference impedance. And, the region of the distance from the open portion 22op (the other end of the extension line L) of the housing 22 to an even multiple (twice) of the wavelength λ at the lowest frequency (6 GHz) of the oscillation signal is only the position P. Therefore, the high impedance range generated is the narrowest. Therefore, in the present embodiment, unnecessary radiation generated from the housing 22 can be effectively reduced.

When the extension line L is an aerial wiring, the wavelength is not shortened according to the dielectric constant. Therefore, for the calculation of the distance to the high impedance point P, the actual size of the line length of the extension line L may be used.

The configuration in which the other end of the extension line L is open can be, for example, the configuration shown in FIG. 26 (b). As can be seen in comparison with the configuration of FIG. 11B, the configuration of FIG. 11B has the other end of the metal line 35 constituting the extension line L on the back surface of the main board 20 on the back surface of the main board 20. The other end of the metal line 35 is open by connecting to a non-grounding pattern 37 that is not connected to the arranged grounding pattern 20c.

The configuration in which the other end of the extension line L is open is shown in FIGS. 14 (b), 15 (a) to (c), 16 (a) to (c), 17 and 18 and FIGS. The same applies to the configuration of 19. Also in these cases, similarly to the above, a non-grounding pattern that is not connected to the grounding pattern 20c arranged on the front surface or the back surface of the main board 20 may be provided, and the other end of the extension line L may be connected to this non-grounding pattern. , The illustration is omitted.

Therefore, in the present embodiment, by opening the other end of the extension line L, the point P in the high impedance range can be positively lowered in impedance, so that the generation of unnecessary radiation can be further eliminated. Is possible.
(Modification example)
As described above, when the distance from the high impedance point P to the open portion 22 op is an even multiple (for example, 1/2) of 1/4 of the wavelength λ, the high impedance range of the housing 22 can be limited to the point P. However, it is possible to apply the method described in the fourth embodiment also in the present embodiment.

That is, when the distance from the high impedance point P to the open portion 22 op is made an even multiple (for example, 1/2) or more of 1/4 of the wavelength λ, the high impedance point P can also be prevented from occurring. Further, when the distance from the high impedance point P to the open portion 22 op is further extended to be an odd multiple (for example, 3/4) of the wavelength λ, the high impedance point P is directly set to low impedance. be able to.

Also, with respect to FIGS. 20 and 21 in the third embodiment, instead of providing a grounding point at a distance of an odd multiple (for example, 1/4) of the wavelength λ from the high impedance point, the high impedance point The same effect can be obtained by providing an open portion at a distance even multiples (for example, 1/2) of the wavelength λ. Further, in FIG. 21, the high impedance point P is set to low impedance by providing the grounding point 22z at a distance of even multiples (for example, 1/2) of the wavelength λ from the high impedance point P via the extension line R2. However, the same effect can be obtained by providing an open portion at an even-numbered multiple (for example, 3/4) of the wavelength λ from the high impedance point P via an extension line. ..

(About the development view of the housing 22)
<When the connection between the sides is weak>
In the expanded view of the housing 22 shown in FIG. 7, when the housing 22 is assembled, the side surfaces b, c, d, and e are weakly connected to each other. There is no signal propagation between eb. Therefore, since it is only necessary to consider the signal propagation between the four side surfaces b, c, d, e and the top surface a, the developed view of the housing 22 shows the top surface a as shown in FIG. 24. You only have to think about the development centered on it. Therefore, in the developed view of the housing 22 of FIG. 24, when the left corner portion 22r of the front surface b is grounded, the oscillation signal propagates from the left corner portion 22r of the front surface b into the front surface b, and then the front surface b and the sky. It propagates to the top surface a via the ba tangent line with the surface a, and further connects the points of the propagation distance λ / 4 when the signal propagates from the top surface a to each side surface c, d, e other than the front surface b. The line is indicated by a solid line, the line connecting the points having a propagation distance of λ / 2 is indicated by a broken line, and the line connecting the points having a propagation distance of 3λ / 4 is indicated by a dash-dotted line.

<When the connection between the sides is strong>
On the other hand, as shown in FIG. 25 (a), when the parts where the adjacent side surfaces are in contact (tangential part) are firmly joined by soldering, for example, and the connection between the adjacent side surfaces is strong, the side surfaces are formed. In addition to the signal propagation between b, c, d, e and the top surface a, it is necessary to consider the signal propagation between the side surfaces bc, cd, d-e, and e-b. Therefore, not only the signal propagation on the developed view centered on the top surface a as shown in FIG. 24, but also the signal propagation between the side surfaces when the other side surfaces are developed centered on the side surfaces b, c, d, and e. Also need to be taken into account.

For example, in FIG. 25 (b), the left side surface (e'plane) developed from the rear surface d and the front surface (b'plane) developed from the right side surface c are added. Further, the grounding point on the left side surface e corresponding to the grounding point 22r at the left corner of the front surface b is described as 22r', and the corresponding grounding point on the two newly developed side surfaces b'and e'is 22r. It is written as'', 22r'''.

In FIG. 25 (b), similarly to FIG. 24, the propagation distance λ / 4 is set in the propagation path of the ground contact point 22r → the front surface b → the tangent to ba → the top surface a → the side surfaces c, d, and e. In addition to the line connecting the points, the line connecting the points with the propagation distance λ / 2, and the line connecting the points with the propagation distance 3λ / 4, the grounding point 22r'→ inside the left side e → e-a tangent → top surface Inside a → Propagation path of each side surface b, c, d, grounding point 22r'' → Inside newly developed side surface b'→ inside b'-c tangent → Inside left side surface c → inside c-a tangent → Inside top surface a → Propagation path of each side surface d and e, and grounding point 22r'''→ newly developed side surface e'inside → e'-d tangent line → rear surface d inside → da tangent line → top surface a inside → each side surface b , C, in the propagation path of c, the line connecting the points of the propagation distance λ / 4, the line connecting the points of the propagation distance λ / 2, and the line connecting the points of the propagation distance 3λ / 4 are described, and further, they are described. In the overlapping part of the lines, each line selected and connected so that the shortest distance from each grounding point 22r, 22r', 22r'', 22r'''is λ / 4, λ / 2, 3λ / 4 Is indicated by a solid line, a broken line, and a one-point chain line in the figure, and each of these lines finally represents each line of propagation distances λ / 4, λ / 2, and 3λ / 4 from the ground contact point 22r.

As described above, when the side surfaces of the housing 22 are strongly connected to each other, it is necessary to supplement the development drawing in consideration of all the electrically strongly connected paths.

(Other embodiments)
In the above description, the oscillation frequency range of the oscillation signal of the VCO / PLL circuit 3 is set to 6 to 8 GHz for receiving TV broadcast waves, but the present invention is not limited to this, and other frequency ranges may be used.

Further, although the circuit configuration of the tuner IC 10 is specifically illustrated in FIG. 1, it goes without saying that other configurations may be added or changed to this configuration.

Further, in the above description, the tuner device is illustrated as a tuner device for receiving television broadcasts, but it goes without saying that the tuner device can be similarly applied to a tuner device for recording / playback.

As described above, in the present invention, when the housing covering the oscillating portion arranged on the board is connected to the board and grounded, the impedance is higher than the predetermined impedance with the grounding point of the housing to the board as the reference impedance. Since the grounding point is arranged at a position where the overlapping range of the housing portion is narrowed or eliminated, unnecessary radiation from the housing can be effectively reduced, and it is applied to a tuner device for receiving TV broadcasts or recording / reproducing. It is useful.

3 VCO / PLL circuit (oscillator)
10 Tuner IC (tuner section, signal processing section)
20 Main board (board)
20a Through hole 20c Grounding pattern (ground part)
20e to 20h, 20x land 20m Wiring pattern (extension line)
22 Housing 22h-22k Legs 22l-22o Holes 22c, 22q-22s Protrusions 22r 1st location 22w 2nd location 22s 3rd location 22j, 22v, 22w',
22x, 22y, 22z Grounding point a Top surface b Front surface c Right side surface d Rear surface e Left side surface k Lower side part A to F High impedance range L, L2 to L7, R Extension line 23 F type connector (connector part)
24 RF cable (signal cable)
25 Soldering 36 Metal leaf spring

Claims (14)

A signal processing unit that processes high-frequency signals, including an oscillating unit that outputs an oscillating signal,
A display unit that displays images and
A substrate on which the signal processing unit is arranged and having a ground unit,
A conductive housing connected to a first location of the ground portion and a second location different from the first location is provided.
In the housing, the first region and the second region are located in regions separated from the first location and the second location located in the ground portion by an odd multiple of 1/4 of the wavelength of the oscillation signal, respectively. Satisfies the predetermined first high impedance condition by the position of
By the first location, said first region of a given said first high impedance satisfying the housing, by said second location, said of the housing that satisfies a predetermined first high impedance condition A display device characterized in that the distance between two points where the second region overlaps is λ / 10 or less with the wavelength of the oscillation signal as λ. A signal processing unit that processes high-frequency signals, including an oscillating unit that outputs an oscillating signal,
A display unit that displays images and
A substrate on which the signal processing unit is arranged and having a ground unit,
A conductive housing connected to a first location of the ground portion and a second location different from the first location is provided.
In the housing, the first region is located in a region separated from the first location by an odd multiple of 1/4 of the wavelength of the oscillation signal, thereby satisfying a predetermined first high impedance condition.
Wherein the housing, the Grand said second portions located in outer in a region apart even multiple distance of a quarter of the wavelength of the oscillating signal, when the second region is located, a predetermined second Satisfies the high impedance condition of
The first region of the housing that satisfies the predetermined first high impedance condition by the first location, and the first region of the housing that satisfies the predetermined second high impedance condition by the second location. the distance between two points and two regions overlap is, the display device you being disposed on the wavelength becomes lambda / 10 or less as lambda position of the oscillating signal. The display device according to claim 1 or 2 , wherein the wavelength of the oscillation signal is a wavelength at the lowest frequency in the frequency variable range of the oscillation unit. An extension line for connecting the housing and the first location is provided.
The display device according to any one of claims 1 to 3 , wherein the first place is arranged at a position separated from the housing. An extension line for connecting the housing and the second location is provided.
The display device according to any one of claims 1 to 4 , wherein the second place is arranged at a position separated from the housing. The housing is arranged in a predetermined area of the substrate and
The display device according to claim 5 , wherein the second location is arranged in a predetermined area of the substrate. A connector portion provided in the housing and to which a signal cable is connected is provided.
The display device according to any one of claims 1 to 6 , wherein the first region and the second region are located at a position separated from the connector portion by a predetermined distance or more. The substrate has a third location.
The third location is characterized in that the third region of the housing whose impedance is lower than a predetermined threshold value is arranged so as to overlap at least one of the first region and the second region. The display device according to any one of claims 1 to 7. The third location is connected to the ground portion and is connected to the ground portion.
The display device according to claim 8 , wherein the third region is located in the housing in a region separated from the third location by an even multiple of 1/4 of the wavelength of the oscillation signal. The third place is not connected to the ground part.
The display device according to claim 8 , wherein the third region is located in the housing in a region separated from the third location by an odd multiple of 1/4 of the wavelength of the oscillation signal. An extension line for connecting the housing and the third location is provided.
The display device according to any one of claims 8 to 10 , wherein the third place is arranged at a position separated from the housing. The housing is arranged in a predetermined area of the substrate and
The display device according to any one of claims 8 to 11 , wherein the third place is arranged in a predetermined area of the substrate. The display device according to any one of claims 1 to 12 , wherein the oscillation frequency range of the oscillation signal is 2 GHz or more. The signal processing unit
The display device according to any one of claims 1 to 13 , wherein the tuner unit receives a broadcast signal or a wireless communication unit that transmits and receives an information signal.

Images