JP6848274B2 - 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 tuner device for a display device that reduces unnecessary radiation, Patent Document 1 states that the shield case (metal housing) accommodating a tuner IC is vertically, horizontally, deeply, and diagonally (the linear distance between the farthest vertices). ) Are set to be shorter than the half wavelength of the highest frequency of the source oscillation frequency of the oscillator IC 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 the 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 1/4 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 the tuner device have been integrated and miniaturized, there is a limit to the miniaturization of the 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 range of high impedance is generated in the metal housing, and a large amount of unnecessary radiation is generated from this range.

Further, in the technique described in Patent Document 1, the diagonal dimension (straight line distance between the farthest vertices) of the housing, for example, the upper left corner of the front surface of the rectangular 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. The wavelength (λ / 2) is greatly exceeded, which also results in large unwanted radiation.

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 that in a tuner device of a display device in which a housing for accommodating an oscillation unit is arranged on a substrate, the size of the housing such as vertical and horizontal is the maximum oscillation frequency of the oscillation unit. Even if the wavelength is longer than half a 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 at the portion of the housing having high impedance with the grounded portion of the housing as the reference impedance, so that the portion of the housing having high impedance is forced. A grounding point that makes the impedance low is provided to reduce unnecessary radiation.

That is, the display device of the invention according to claim 1 includes an oscillation unit that outputs an oscillation signal, a signal processing unit that processes a signal having a frequency higher than 2 GHz, a display unit that displays an image, and the signal processing unit. A substrate having a ground portion and a conductive housing connected to a first portion of the ground portion and a second location different from the first location, the first location and the second location. The location is such that the first region of the housing whose first region has an impedance higher than the reference impedance, which is the impedance of the first location, has an impedance lower than the reference impedance due to the second location. The first region is arranged at a position overlapping with at least a part of the second region of the above, and the first region is a region separated from the first location by an odd multiple of 1/4 of the frequency of the oscillation signal in the housing. The second region is characterized in that the second region is located at a position in the housing at a distance of an even multiple of 1/4 of the frequency of the oscillation signal from the second location .

The display device of the invention according to claim 2 includes an oscillation unit that outputs an oscillation signal, a signal processing unit that processes a signal having a frequency higher than 2 GHz, a display unit that displays an image, and the signal processing unit. A substrate having a ground portion and a first conductor portion, and a conductive housing connected to a first portion of the ground portion and a second portion of the first conductor portion are provided, and the first location and the first conductor portion are provided. In the second location, the first region of the housing, which has an impedance higher than the reference impedance which is the impedance of the first location by the first location, has an impedance lower than the reference impedance by the second location. The first region is arranged at a position overlapping with at least a part of the second region of the housing , and the first region is a region separated from the first location by an odd multiple of 1/4 of the wavelength of the oscillation signal in the housing. The second region is characterized in that the second region is located at a position in the housing at an odd multiple of 1/4 of the wavelength of the oscillation signal from the second location .

According to the first and second aspects of the invention, when the housing is connected to, for example, the first portion of the ground portion arranged at the corner thereof, a part or all of the first region of the housing becomes high impedance by the first portion. However, since the second portion overlaps with the second region of the housing having low impedance, unnecessary radiation in the first region of the housing having high impedance is reduced. Therefore, even if the vertical, horizontal, and other sizes of the housing exceed half the wavelength (λ / 2) of the wavelength λ of the highest oscillation frequency of the oscillating unit, the first region of the housing that has high impedance Part or all of the impedance can be reduced by the second location, and unnecessary radiation can be effectively reduced.

Moreover, unlike the conventional case, it is not necessary to evenly arrange a large number of grounding points inside or on the side of the housing, and the housing can be manufactured with a simple configuration at a low price .

Further, in the inventions according to claims 1 and 2 , the first region separated from the first location by an odd multiple of 1/4 of the wavelength of the oscillation signal has a high impedance, but the impedance is low within that range. Since the second regions overlap, the first region can be reduced and unnecessary radiation can be effectively reduced .

Further, in the invention according to claim 1 , the second region connected to the ground portion is located at a position in the housing that is an even multiple of 1/4 of the wavelength of the oscillation signal from the second location. The impedance of the second region can be effectively reduced. Therefore, the first region having high impedance can be effectively reduced, and unnecessary radiation can be effectively reduced .

Further, in the invention according to claim 2 , the second region of the housing connected to the second portion of the first conductor portion is separated from the second portion by an odd multiple of 1/4 of the wavelength of the oscillation signal. Since it is located at the position of the housing, the impedance of the second region can be effectively reduced. Therefore, the first region of the housing having high impedance can be effectively reduced, and unnecessary radiation can be effectively reduced.

In the invention according to claim 3 , the housing is connected to the first location of the ground portion and a third location different from the second location, and the housing is connected to the reference impedance by the third location. Also has a third region with high impedance, where the wavelength of the oscillation signal is λ, the first region and the third region overlap at two points, and the distance X between the two points satisfies the following conditions. 0 <X ≤ λ / 10
It is characterized by that.

In the invention according to claim 3 , since the distance X between the two points where the first region and the third region overlap satisfies the condition of 0 <X ≦ λ / 10, the whole or all within the region between the two points If a part is set to the second region where the impedance is lowered by the second place, it is possible to lower the impedance of both the first region and the third region by one second place.

In the invention according to claim 4 , the housing has an upper portion of a rectangle and a side portion extending from each side of the upper portion and perpendicular to the upper portion, and the first portion is a short portion of the upper portion. The second portion is arranged on a side portion extending from the side on the hand side, and the second portion is arranged on a side portion extending from the longitudinal side of the upper portion.

The invention according to claim 5 is characterized in that the first region and the second region are each a plurality of regions.

The invention according to claim 6 is characterized in that the first place and the second place are each a plurality of places, and the number of the second places is equal to or less than the number of the first places. To do.

The invention according to claim 7 is characterized in that the first location is at least two locations, and the second location includes one said second region that overlaps the first region at least two locations.

In the inventions of claims 6 and 7 , the number of the second locations is limited to the same number or less with respect to the number of the first locations. Therefore, as in the conventional case, the conductor pillar connecting the housing and the ground of the substrate. It is not necessary to arrange a large number of them evenly, and it is possible to simplify and reduce the cost of the housing configuration.

The invention according to claim 8 is characterized in that the second portion is arranged at a predetermined position on the substrate away from the housing by an extension line connected to the housing.

In the invention according to claim 8 , since the second place can be arranged at an arbitrary position away from the case by the extension line extending from the case, the second place that makes the high impedance range generated by the first place low impedance. It is possible to increase the degree of freedom in the placement position of.

The invention according to claim 9 is characterized in that the housing is arranged in a predetermined area of the substrate, and the second place is arranged in the predetermined area.

The invention according to claim 10 is characterized in that the extension line is a wiring portion arranged on the substrate.

In the inventions of claims 9 and 10 , since the extension line is arranged in a predetermined region of the substrate located below the housing, other components of the tuner device, such as digital, are located near the side of the housing on the substrate. Even when processing circuits and audio circuits are arranged close to each other, it is possible to easily reduce the high impedance range to low impedance without being disturbed by these devices.

The invention according to claim 11 is characterized in that the first region or the second region includes a region corresponding to a change range of the wavelength of the oscillation signal.

In the invention according to claim 11, even if the first region having high impedance changes according to the wavelength change accompanying the frequency change of the oscillation signal of the oscillating unit, the second path having low impedance including the change range. Therefore, no matter which oscillation frequency the oscillating unit oscillates, unnecessary radiation is always effectively reduced anywhere in the housing.

The invention according to claim 12 is characterized in that the housing is provided with a connector portion to which a signal cable is connected, and the first region is in the vicinity of the connector portion.

In the invention according to claim 12 , for example, in a housing in which a signal cable for television broadcasting is connected to a connector portion, even if a range near the connector portion becomes a high impedance as a first region due to the first location, the first region is the same. Since the two locations set a part or all of the first region as the second region to make the impedance low, the impedance distribution on the housing is not easily affected by variations in the state (type, material, shape, etc.) of the signal cable. It is possible to suppress the generation of unnecessary radiation due to variations in the state of the signal cable.

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, unnecessary radiation can be effectively reduced as a display device provided with a tuner device for receiving television broadcasts.

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 display device of the present invention, even if a range of high impedance is generated in the housing due to the grounded portion, a second portion for forcibly lowering the impedance is arranged on the substrate. Therefore, unnecessary radiation generated from the housing can be effectively reduced, and the number of grounding points on the grounding potential portion of the board can be limited to an extremely small number as compared with the conventional case, so that the housing configuration can be simplified and inexpensive. It is possible to do.

FIG. 1 is a block diagram showing a circuit configuration of a tuner IC included in the tuner device of the display 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 points are grounded, and FIG. 4B shows a case where three points 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 a high impedance range generated in the housing when the housing is grounded in two places, FIG. 6A shows the generation range in a plan view, and FIG. 6B shows a developed view of the housing. Indicates the range of occurrence of. 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 right corner portion of the housing are grounded on the main board. FIG. 10A shows a high impedance range generated in the housing when the front left corner and the rear right corner of the housing are grounded on the main board, and FIG. 10B shows the housing. It is a figure which shows the high impedance range in the expanded state. In FIG. 11, the high impedance range generated when the left corner portion on the front surface and the right corner portion on the rear surface of the housing are grounded as the first grounding point is determined by the second grounding point arranged on the lower side portion of the left side surface of the housing. It is a figure which shows the state of low impedance. FIG. 12 is a diagram showing a state in which the other high impedance range generated in the housing by the second grounding portion of FIG. 11 is also lowered. FIG. 13 shows a modified example of the position of the second grounding point in FIG. 12, and is a diagram arranged at a point within 1/20 of the wavelength λ from an even multiple of 1/4 of the wavelength with respect to the high impedance point. Is. FIG. 14 is a diagram showing another modification of the position of the second ground contact portion shown in FIG. FIG. 15 is a diagram showing how the two high impedance ranges generated in the housing shown in FIG. 7 are reduced in impedance by a second grounding portion arranged on the lower side of the right side surface of the housing. FIG. 16 shows that the two high impedance ranges generated in the housing by the second grounding portion provided on the lower side of the left side surface of the housing and the second grounding portion provided on the lower side of the right side surface of the housing are lowered. It is a figure which shows the state of making into impedance. FIG. 17 shows the connection of the second ground contact portion provided on the housing to the main board. FIG. 17 (a) shows the case where the legs are provided on the housing, and FIG. 17 (b) shows the case where the housing is directly connected. Figure (c) shows the case of soldering to the main board, the figure (c) shows the case of using the metal leaf spring, the figure (d) shows the side view of the metal leaf spring, and the figure (e) shows the case of using the metal leaf spring. The cross-sectional view of each is shown. FIG. 18 shows a second embodiment of the present invention, and is a diagram showing how the high impedance range is lowered by a second grounding portion provided on the lower side of the left side surface on the developed view of the housing. FIG. 19 shows a third embodiment of the present invention, FIG. 19A is a view in which a second ground contact portion provided in the housing is arranged at a position away from the housing, and FIG. 19B is a second. It is sectional drawing which shows the structure around the grounding part. FIG. 20 shows a modified example of the third embodiment, and FIG. 20A is a view in which a second grounding point provided in the housing is arranged in a region of the main board located below the housing, FIG. 20B. ) Is a diagram showing the configuration around the second grounding point, and FIG. 3C is a sectional view taken along line CC of the wiring pattern of FIG. 2B. FIG. 21 shows a fourth embodiment of the present invention, in which other grounding points provided on the housing are arranged at positions away from the housing. FIG. 22 shows a modified example of the extension line arranged in the area of the main board located below the housing, FIG. 22A is a diagram showing an example in which the extension line is arcuate, and FIG. 22B is a diagram showing an example in which the extension line is arcuate. A diagram showing an example of combining an arc shape and a linear shape, and FIG. 3C is a diagram showing an example of a wavy shape. FIG. 23 shows a second modification of the extension line, FIG. 23A is a plan view of the connection portion between the housing and the main board, FIG. 23B is a sectional view, and FIG. 23C is a bottom surface. It is a figure. FIG. 24 shows a third modification of the extension line, and is a perspective view in which the extension line is configured by using a metal wire. FIG. 25 shows a fourth modification of the extension line, and is a cross-sectional view of a connection portion between the housing and the main board when the extension line is configured by using a linear conductor and a wiring pattern. FIG. 26 shows a fifth modification of the extension line, and is a cross-sectional view of a connecting portion between the housing and the main board when the extension line is configured by using a leaf spring-shaped conductor. FIG. 27 shows a fifth embodiment of the present invention, in which FIG. 27A is a view in which an open portion provided in a housing is arranged at a position away from the housing, and FIG. 27B is a configuration around the open portion. It is a figure which shows. FIG. 28 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. 29 (a) is a development view of the housing when the electrical connections between the side surfaces of the housing are strong, and FIG. 29 (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.

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 differential 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 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. There is.

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 the radio is wireless. In the case of a communication oscillation signal, the frequency is the same as that of the tuner oscillation signal, so the predetermined threshold value is approximately 2 GHz.

As shown in FIG. 2, an F-type connector (connector portion) 23 is attached to the housing 22, and an RF cable (signal cable) for transmitting a television broadcasting frequency signal (RF signal) to the F-type connector 23. 24 is connected and an 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 a through hole 20a formed in the main board 20. By soldering 25, the leg portion 22a is formed into a conductive pattern (grounding pattern = ground portion) (grounding potential portion) 20c of the grounding potential formed on the upper surface and the lower surface of the main board 20 through the through hole 20a of the main board 20. It is grounded.

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, and is further formed on a microcomputer, a memory, a power supply component, and a main board 20 that perform processing for 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 = even if they are minimized in consideration of the sizes of the tuner IC 10, the crystal oscillator 15, the capacitor, the inductor, and other chip components 16 housed therein. 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 same 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 the first grounding point)
First, the first grounding point is arbitrarily specified. In the present embodiment, the first grounding point is the case where the number of grounding points shown in FIG. 4A is small, that is, the two points of the front left corner and the rear right corner in the figure are the first grounding points. The case where it is specified as a place will be described as an example. The first designated portion may be another corner portion, or may be three or four locations as shown in FIGS. 5 (b) and 5 (c).

6 (a) and 6 (b) show that, as described above, when the grounding points are the front left corner portion and the rear right corner portion (first grounding point) of the housing 22, the impedance of the housing 22 is higher than the predetermined impedance. The range of impedance is shown.

The housing 22 is formed into a square pillar shape by processing one metal plate. FIG. 7 shows an unfolded view of the housing 22 and has an upper portion of a rectangle and four side portions extending from each side of the upper portion and perpendicular to the upper portion. Here, in the developed view of the housing 22, the square housing 22 is created by folding the four side surfaces b to e with respect to the top surface a. 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 ground potential portion 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 first 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. Is not connected to the grounding 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 first grounding points of the housing 22, the through holes 20s are the front surface and the back surface of the main board 20 as shown in FIG. In the lands 20f and 20h that are connected to the grounding pattern 20c arranged on at least one of the above and correspond to the other two corners 22t and 22u of the housing 22 that are not grounded, the through holes 20s are as shown in FIG. It is not connected to the ground pattern 20c.

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, in a state where one metal plate is folded to assemble the hollow square housing 22, the lower angle of the left side surface e thereof. Since 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, FIG. 8A is shown. 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 that serves as a 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 becomes an open end and has high impedance. When a plurality of grounding points are provided, the overlapping portion of the grounding point at an odd multiple of λ / 4 has the highest impedance.

Specifically, on the developed view of the housing 22 shown in FIG. 6B, as described above, the left side of the front surface (the side surface extending from the short side of the upper part of the rectangle) b. Since the two points of the corner 22r and the right corner 22s of the rear surface d are the ground potentials, the highest impedance is obtained at odd multiples of λ / 4 from these two ground points (first place) 22r and 22s. It becomes. In the figure, an arc-shaped high impedance range (No. 1) in which a high impedance portion λ / 4 away from the left corner portion 22r of the front surface b and a high impedance portion λ / 4 away from the right corner portion 22s of the rear surface d overlap. 1 region) A (this high impedance range is surrounded by a thick broken line in the figure), a high impedance portion λ / 4 away from the right corner 22s of the rear surface d, and λ / 4 3 from the left corner 22r of the front surface b. An arc-shaped range (first region) (this high impedance range is surrounded by a thick broken line in the figure) B where the high impedance portion that is twice as far away overlaps is drawn. 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. Further, in the arc-shaped high impedance ranges A and B, the arc-shaped lines shown by the thick solid lines are each located at odd multiples of λ / 4 from the grounding points (first point) 22r and 22s, respectively. This is the region with the highest impedance. Further, the impedance ranges A and B indicate a range including a distance of λ / 20 times the wavelength λ at the oscillation frequency f from the high impedance region of the arcuate line shown by the thick solid line. Further, there are one or two high impedance points corresponding to each frequency f in the high impedance ranges A and B, respectively, and the higher the frequency f, the smaller the distance between the two points. When the distance between these two points is large (separated), the radiation direction of the radio wave is dispersed, but when the distance is short, the radiation directivity becomes stronger. The strength of this radiation directivity has a gradation within the impedance ranges A and B, but in the figure, it is simply expressed in three stages due to the difficulty of expression.

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 lower corner portion 22q of the right side surface c has the same potential as the right corner portion 22s of the rear surface d. Above, there are four grounding points. 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. In the high impedance ranges C and D, the distances from the two ground contact points of the lower corner portion 22p of the left side surface e and the left corner portion 22r of the front surface b are equal, and the lower corner portion 22q of the right side surface c and the rear surface d. Since the distances from the two ground contact points with the right corner portion 22s are equal, the shape becomes linear. Further, in the high impedance ranges C and D. The linear line shown by the thick solid line is a region that is an odd multiple of λ / 4 and has the highest impedance at all of the grounded locations (first location) 22p, 22r, 22q, and 22s. Further, the high impedance ranges C and D indicate a range including a distance of λ / 20 times the wavelength λ at the oscillation frequency f from the high impedance region of the linear line shown by the thick solid line. In the high impedance ranges C and D, the radiation directivity is weak and there is no gradation.

10 (a) and 10 (b) show 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. Shown. 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.

(Lower impedance in the high impedance range in the 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 the present embodiment, a configuration is adopted in which the high impedance range is surely lowered. This will be described in detail below.

FIG. 11 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 reducing the impedance in the high impedance range is shown by taking as an example the case where the grounding pattern 20c of the main board 20 is grounded as the grounding point.

In the figure, the high impedance range B (see FIG. 6) generated on the developed view of the housing 22 is reduced in impedance. 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 at a position that is an odd multiple of λ / 4 from the grounded portion with the grounded portion as the reference impedance. On the other hand, in a region (second region) separated by an even multiple of 1/4 of the wavelength λ of the oscillation signal, the impedance becomes lower than the predetermined impedance. Therefore, in FIG. 11, with respect to a point at an oscillation frequency of 6.8 GHz, which has a particularly high radiation directivity in the high impedance range B on the developed view of the housing 22, this oscillation frequency is shown on the developed view from this point. The left side surface of the housing 22 (extending from the longitudinal side of the upper part of the rectangle) as a position separated by a linear distance by a distance (λ / 2) that is twice the wavelength λ at (6.8 GHz). A second ground contact point (second place) 22w is arranged on the lower side portion k of the side surface) e.

Therefore, in the present embodiment, the high impedance range B (see FIG. 6) generated on the developed view of the housing 22 is the range where the impedance is particularly high and / or the range where the radiation directivity is particularly high is the second grounding point 22w. It is possible to make the impedance lower than the predetermined impedance. As a result, it is possible to effectively reduce the generation of unnecessary radiation from the high impedance range B generated by the two first grounding points 22r and 22s in FIG. 6 by the second grounding point 22w.

In FIG. 11, a case where a wide range of the high impedance range B of the housing 22 is reduced in impedance by the second grounding portion 22w has been described, but the second grounding portion 22w is a casing as shown in FIG. Even within the other high impedance range A (see FIG. 6) that occurs in the body 22, the housing starts from a point near a part with a high impedance value (a part where the oscillation frequency is around 6.8 GHz) (this point is indicated by a black circle in the figure). On the developed view of the body 22, it corresponds to a position separated by a linear distance by a half wavelength (λ / 2) at the oscillation frequency (6.8 GHz). Therefore, it is possible to reduce the impedance over a wide range of the high impedance range A of the housing 22 by the second grounding point (second place) 22w. Therefore, it is possible to reduce the impedance of both the two high impedance ranges A and B of the housing 22 with only one second grounding point 22w, and effectively reduce unnecessary radiation from these ranges A and B. It is possible.

Therefore, in the present embodiment, both of the two high impedance ranges A and B generated by the two first grounding points 22r and 22s are made low impedance in common at the one second grounding point 22w. Therefore, it is possible to limit the number of second grounding points that lower the impedance of the high impedance range to a smaller number than the number of first grounding points that generate the high impedance range.

Therefore, in the present embodiment, unlike the conventional case, it is not necessary to arrange the grounding posts (grounding points) as evenly as possible along the inner side and the end portion of the housing 22, and the configuration of the housing 22 can be simplified. And it is possible to make it at a low price.

In the present embodiment, the second grounding point is arranged at a point that is exactly an even multiple of 1/4 of the wavelength λ of this frequency with respect to the point where the impedance becomes high at the oscillation frequency. The second grounding point may be arranged at a point sufficiently close to the point, even if the distance is slightly even from an even number of 1/4 of the wavelength λ.

Normally, the impedance can be kept low in the range of λ / 20 from the grounding point, so the grounding points of the housing and board that are not particularly limited in cost and shape are often designed at intervals of λ / 10 (grounding). The center between the points is just λ / 20 from the grounding point).

For this reason, also in the present invention, the second grounding point is provided at a point within 1/20 of the wavelength λ from a distance that is an even multiple of 1/4 of the wavelength λ of this frequency with respect to the point where the impedance becomes high at the oscillation frequency. If it is arranged, it may be considered that the effect of the present invention can be sufficiently obtained.

For example, in FIG. 13, from the point that the grounding point 22r and 22s are separated from both the grounding points 22r and 22s by an odd multiple of 1/4 of the wavelength λ of the oscillation frequency and have high impedance, from the circle of the radius of λ / 20 of this oscillation frequency. A second grounding point 22w is provided at a point evenly separated by 1/4 of the wavelength λ.

By doing so, the effect of the present invention can be sufficiently obtained even if there is a restriction on the place where the second ground contact point can be arranged, for example.

Further, in FIG. 14, unlike FIGS. 11 and 13, the housing 22 is grounded at the grounding point (first place) 22r and at another grounding point (third place) 22s', while being grounded at the other grounding point (third place) 22s'. An arcuate region shown by a thick solid line in the figure with high impedance is generated at an odd multiple (1 times in the figure) of 1/4 of the wavelength λ of the oscillation frequency from the grounding point 22s', and the other grounding point. An arc-shaped region shown by a thick broken line in the figure having high impedance is generated at an odd multiple (3 times in the figure) of 1/4 of the wavelength λ of the oscillation frequency from 22r. These two high impedance regions overlap at two points H1 and H2. When the distance between the two points H1 and H2 having high impedance is 1/10 or less of the wavelength λ of the oscillation frequency, the second grounding point (second point) 22w'is 1/4 of the wavelength λ of the oscillation frequency. Two points H1 and H2 having high impedance are included in a circle whose radius is 1/20 of the wavelength of the oscillation frequency, centered on the portion G separated by an even multiple (twice in the figure) of. The position of the second ground contact point 22w'may be selected.

(First modification)
FIG. 15 shows a first modification of the position of the second ground contact portion shown in FIG.

In FIG. 11, since the two first grounding points 22r and 22s are located at point-symmetrical positions on the developed view of the housing 22, in this modified example, in FIG. 15, the second grounding point of FIG. 11 is shown. Instead of 22w, the second grounding point (second place) 22x is located at a position symmetrical with the second grounding point 22w, that is, on the lower side portion n of the right side surface c on the developed view of the housing 22. Have been placed.

Therefore, also in this modification, it is possible to reduce the impedance of both the two high impedance ranges A and B generated by the two first grounding points 22r and 22s with only one second grounding point 22x. Is.

(Second modification)
FIG. 16 shows a second modification of the position of the second ground contact portion shown in FIG.

In this modification, a second grounding point for lowering the impedance of the two high impedance ranges A and B by combining the configuration of FIG. 12 showing the present embodiment and the configuration of FIG. 15 showing the first modification. As (second location), two grounding portions 22w in FIG. 12 and a second grounding portion 22x in FIG. 15 are arranged.

When both of the two second grounding points 22w and 22x are arranged, for example, one of the grounding points (for example, 22w) is placed near the position at the oscillation frequency of 6.8 GHz in the high impedance ranges A and B. Place it at a distance of half a wavelength (λ / 2), and place the other grounding point (for example, 22x) half a wavelength from the vicinity of the position at another oscillation frequency (for example, 6.9 GHz) within the high impedance range A and B. If the high impedance ranges A and B are arranged at positions separated by a distance of (λ / 2), the high impedance ranges A and B can be lowered to a higher range.

In the embodiment and the first and second modifications, the second ground contact points 22w and 22x are arranged at a linear distance of half a wavelength (λ / 2) (that is, λ / 4) on the developed view of the housing 22. Although they are arranged at positions separated by 2 times), the present invention is not limited to this, and when the size of the housing 22 is large such as in the vertical and horizontal directions, it is 4 times or more the wavelength λ of the oscillating signal λ / 4. The high impedance range generated in the housing can be effectively reduced even if the positions are evenly separated from each other.

Further, in the embodiment and the first and second modifications, as illustrated in FIGS. 12, 15 and 16, the case where the first ground contact point is set to two corner portions 22r and 22s has been described. , The position of the first grounding point may be another corner, and the number of the first grounding points is not limited to two, and the same applies to three or four or more. Of course.

(Specific configuration of the second grounding point)
FIG. 17 shows a specific configuration in which the second grounding points 22w and 22x are connected to the grounding pattern 20c of the main board 20.

In FIG. 6A, the second ground contact portion 22w is provided with the leg portion 22y on the lower side portion k of the left side surface e of the housing 22 in the same manner as the first ground contact portion 22r arranged at the corner portion of the housing 22. On the other hand, through holes 20a are arranged in the main board 20 at positions corresponding to the legs 22y, and when the housing 22 is attached to the main board 20, the left side surface e of the housing 22 The leg portion 22y is inserted through the through hole 20a and soldered 25, and the leg portion 22y of the housing 22 is connected to the grounding pattern 20c on the lower surface of the main board 20 via the through hole 20a of the main board 20.

Further, in FIG. 3B, the position of the second left side surface e of the housing 22 to be the second grounding point 22w is soldered 25, and the second grounding point 22w of the housing 22 is directly main. It is connected to the ground pattern 20c on the board 20.

Further, in FIG. 6C, a metal leaf spring 36, which is a surface mount component, is used. The metal leaf spring 36 has a substantially U-shaped cross section as shown in FIG. 3D, and two plate-shaped pieces 36a and 36a arranged to face each other as shown in FIG. The portion that is pressurized in the direction and becomes the second ground contact portion 22w on the left side surface e of the housing 22 is sandwiched and fixed between the plate-shaped pieces 36a and 36a of the metal leaf spring 36, and the fixed metal plate is fixed. The bottom surface of the spring 36 is connected to the grounding pattern 20c on the top surface of the main board 20 by reflow soldering.

(Second embodiment)
FIG. 18 shows a second embodiment of the present invention.

In the present embodiment, the impedance in the vicinity of the F-type connector 23 is reduced on the developed view of the housing 22.

As shown in FIGS. 10A and 10B, when the left corner portion 22r and the right corner portion 22v of the front surface b of the housing 22 are used as the first grounding points, a high impedance is provided at the upper center portion of the front surface b. Range (first region) E has occurred. As shown in FIG. 10A, the F type connector 23 is connected to the RF cable 24 that transmits the television broadcast wave. Therefore, depending on the material and structure of the RF cable 24 or the mounting state such as how to bend it, Unnecessary radiation is also generated on the RF cable 24 due to the influence of unnecessary radiation generated in the vicinity of the F type connector 23. In the figure, the places where unnecessary radiation is generated on the RF cable 24 are illustrated in parentheses.

In the present embodiment, as shown in FIG. 18, the oscillation frequency (6.8 GHz) is from the high impedance point generated at the oscillation frequency of 6.8 GHz in the high impedance range E generated in the upper center portion of the front surface b of the housing 22. ) Is a position separated by a linear distance on the developed view of the housing 22 by a half wavelength (λ / 2) distance, and a second ground contact point (second grounding point) is located at the position of the lower side portion k of the left side surface e of the housing 22. Location) 22z is arranged.

Therefore, in the present embodiment, the high impedance range F generated in the upper center portion of the rear surface d of the housing 22 remains, but the height generated in the upper center portion of the front surface b of the housing 22 due to the second ground contact portion 22z. Since a wide range of the impedance range E can be reduced in impedance, unnecessary radiation from this range E can be reduced, and unnecessary radiation generated in the RF cable 24 connected to the F type connector 23 can be effectively reduced. As a result, the impedance distribution on the housing is less affected by the variation in the state (type, material, shape, etc.) of the signal cable 24, and the generation of unnecessary radiation due to the variation in the state of the signal cable is suppressed. There is.

(Third Embodiment)
19 (a) and 19 (b) show a third embodiment of the present invention.

In FIG. 11 showing the first embodiment, the second grounding point 22w is arranged on the lower side k of the left side surface e of the housing 22, but the second grounding point 22w is located at a position away from the housing 22. It is the one that was placed.

Specifically, in FIG. 19A, the distance from the high impedance range B to the lower side portion k of the left side surface e of the housing 22 on the developed view of the housing 22 is VCO / When the distance is less than the half wavelength (λ / 2) at the predetermined oscillation frequency (6.8 GHz in the figure) of the PLL circuit 3, the extension line Lo is connected from the lower side k of the left side surface e of the housing 22. Therefore, a second grounding point (second place) 22wo is arranged at the tip of the extension line Lo.

As shown in FIG. 3B, the extension line Lo is a leg portion 22n provided on the lower side portion k of the left side surface e of the housing 22 in the through hole 20s of the land 20x in the non-grounded state provided on the main board 20. After inserting and soldering 25, one end of the metal line 35 is connected to the soldered 25 portion as the extension line Lo, and the other end of the metal line 35 is used as the second grounding point 22wo as the main board 20. It is connected to the grounding pattern 20c arranged on the back surface of.

Since the metal line 35 is an aerial wiring, in FIG. 19A, the distance from the high impedance range B of the housing 22 to the lower side k of the left side surface e of the housing 22 and the total length of the metal line 35. Is configured to be equal to the half-wavelength (λ / 2) distance at a predetermined oscillation frequency (6.8 GHz in the figure) of the VCO / PLL circuit 3.

Therefore, in the present embodiment, even when the size of the housing is relatively small, the high impedance range B of the housing 22 is reduced in impedance by the second grounding portion 22wo away from the housing 22. It is possible to do.

Further, according to this configuration, as can be seen from FIG. 19A, half wavelength (λ / 2) at the oscillation frequency (6.8 GHz) is obtained from both of the two high impedance ranges A and B of the housing 22. Even if the portion separated by the distance of is outside the developed view of the housing 22, the impedance of both the high impedance ranges A and B is easily lowered by the second grounding portion 22wo separated from the housing 22. It is possible.

(Modification example)
20 (a) to 20 (c) show modified examples of this embodiment.

In the third embodiment, the second grounding point 22wo is arranged outside the housing 22, but in this modification, the second grounding point is located below the housing 22 in the area of the main board. Place in (predetermined area).

In the figure (a), a second ground contact point (second place) is separated from the lower side portion k of the left side surface e of the housing 22 toward the region of the main board located below the housing 22 with an extension line Lo. 22w1 is arranged.

A specific example of this is shown in FIG. 20 (b). In FIG. 3B, the leg portion 22n provided on the lower side portion k of the left side surface e of the housing 22 is soldered 25 to the land 20x of the main board 20. For example, a copper foil constituting the grounding pattern 20c is cut out around the land 20x of the main board 20, and as the extension line Lo extending from the land 20x to the area of the main board located below the housing 22. The copper foil is cut out so that the wiring pattern (wiring portion) 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 constitutes the second grounding point 22w1. To do.

The length of the wiring pattern 20 m is determined as follows. In this modification, since the wiring pattern 20m 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 (er1 / 2). For example, the distance from the position of the high impedance range B of the housing 22 to the lower side k of the left side surface e of the housing 22 is 90% of the wavelength λ / 2 (twice λ / 4) in the air. In this case, the line length of the wiring pattern 20 m may be set to 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 = 8 GHz, the wavelength λ'at the relative permittivity er is
λ'= (1 / (er1 / 2)) λ = (1/2) x (c / f)
c: Speed of light = (1/2) x (3 x 108 / (8 x 109)) = 0.01875m = 18.75mm
Therefore, the line length is 18.75 × (1/4) × 0.1 = 0.46875 mm ≈ 0.5 mm.
Can be calculated.

FIG. 3C is a cross-sectional view taken along the line CC at the location of the wiring pattern 20 m in FIG. When the characteristic impedance of the extension line Lo (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 Lo 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 this modification, since the second grounding point 22w1 is arranged in the area of the main board located below the housing 22, when the microcomputer, memory, or the like is arranged near the outside of the housing 22. Even so, it is possible to satisfactorily arrange the second grounding portion 22w1 from the housing 22 by a length of 20 m of the wiring pattern without being disturbed by these devices.

In this modification, the extension line Lo is composed of a wiring pattern of 20 m and its shape is linear, but in addition, the wiring pattern 20 m may be an arc shape extending around the land 20x or a wave shape. , The through hole formed in the main board 20 may be used to ground the ground pattern 20c on the back surface of the main board 20 to extend the distance.

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

In the first embodiment shown in FIG. 11, on the developed view of the housing 22, the point at the oscillation frequency of 6.8 GHz, which has a high impedance value even in the high impedance range B, is shown on the developed view from this point. The second position is located on the lower side k of the left side surface e of the housing 22 as a position separated by a linear distance of twice (λ / 2) the wavelength λ at this oscillation frequency (6.8 GHz). The grounding point (second place) 22w was newly arranged, but instead of the second grounding point, the peripheral configuration of the first grounding point 22s provided in the housing 22 was modified to obtain the high impedance range B. This is a configuration that lowers the impedance.

Specifically, in FIG. 21, theoretically, the fact that the impedance becomes lower than the predetermined impedance at a position at an even multiple of 1/4 of the wavelength λ of the oscillation signal from the grounding point is used. One end of the extension line L2 is connected to the right corner portion 22s of the rear surface d of the housing 22, the other end of the extension line L2 is grounded, and the grounding point (the other end of the extension line L2) (second place) 22w2 The distance from the extension line L2 and the right corner portion 22s of the rear surface d of the housing 22 to the point where the impedance value is high in the high impedance range B is 1 / of the wavelength λ at the oscillation frequency (6.8 GHz) of the oscillation signal. A configuration set to an even multiple (2 times) (= λ / 2) of 4 is adopted.

Therefore, in the present embodiment, the line length of the extension line L2 does not shorten the wavelength according to the dielectric constant when the extension line L2 is an aerial wiring, so that the oscillation frequency of the oscillation signal (6.8 GHz). The actual size may be obtained by subtracting the distance between the high impedance point and the right corner portion 22s of the rear surface d of the housing 22 from the length of twice the wavelength λ (= λ / 2) in. ..

(Modification example of extension line)
FIG. 22 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 20 g and a linear shape extending from the tip thereof toward the region of the main board located 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 20 g of the land, it is possible to avoid interference with other wiring of the tuner circuit, or to greatly divide the grounding pattern, thereby reducing the grounding effect. An effect that can be prevented occurs.

FIG. 23 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 the region of the main board located 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 L2 to L5.

FIG. 24 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. 25 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. 26 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 even multiple of 1/4 of the wavelength λ.

(Fifth Embodiment)
Subsequently, a fifth embodiment of the present invention will be described with reference to FIG. 27.

In the fourth embodiment (FIG. 21), on the developed view of the housing 22, the ground is grounded at the grounding point 22w2 from the right corner portion 22s of the rear surface d via the extension line L2, but in the present embodiment, the grounding point 22w2 is grounded. Is not grounded, but is an open location, and the length of the extension line L2 is changed.

Specifically, in the present embodiment, on the developed view of the housing 22 of FIG. 27A, one end of the extension line L3 is connected to the right corner portion 22s of the rear surface d, and the other end of the extension line L3 is open. The other end of the extension line L3 is an open portion (second 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. Among the points of the doubled distance (points in the high impedance range B shown in FIG. 6B), the point closest to the right corner portion 22s of the rear surface d is set as the point P, and from this point P to the rear surface d of the housing 22. The total distance between the distance to the land 20s at the right corner of the oscillating signal and the distance from the land 20s to the open portion 22op (that is, the line length of the extension line L3) is the lowest frequency (6 GHz) in the variable frequency range of the oscillation signal. The line length of the extension line L3 is set so as to correspond to an odd multiple (1 times) value (= λ / 4) of 1/4 of the wavelength λ at.

As described above, in the housing 22 in which the oscillation frequency of the oscillating portion is high and the impedance is a distribution constant, the grounded portion of the left corner portion 22r of the front surface b is used as the reference impedance, and the linear distance from this grounded portion on the developed view is λ. At a position P that is an odd multiple (3 times) away from / 4, the impedance becomes higher than a predetermined impedance, but in this embodiment, it oscillates from the open portion 22 op (the other end of the extension line L3) of the housing 22. Since the position P as a location at an odd multiple (1 times) of 1/4 of the wavelength λ at the lowest frequency (6 GHz) of the signal has a lower impedance than the predetermined impedance, the range around the high impedance point P. It is possible to positively reduce the impedance.

When the extension line L3 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 L3 may be used.

The configuration in which the other end of the extension line L3 is open can be, for example, the configuration shown in FIG. 27 (b). As can be seen in comparison with the configuration of FIG. 19B, the configuration of FIG. 19B has the other end of the metal line 35 constituting the extension line L3 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 (first conductor portion) 37 which is an open pattern that is not connected to the arranged grounding pattern 20c.

The configuration in which the other end of the extension line L3 is open is shown in FIGS. 20 (b), 22 (a) to 22 (c), 23 (a) to (c), 24, 25 and FIGS. The same applies to the 26 configurations. 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 L3, 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.

(About the development view of the housing 22)
<When the connection between the sides is weak>
In the developed view of the housing 22 shown in FIG. 7, at the time of assembling the housing 22, the side surfaces bc, cd, d-e, e are weakly connected to each other. There is no signal propagation between −b. 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. 28. You only have to think about the development centered on it. Therefore, in the developed view of the housing 22 of FIG. 28, 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 tangent line of ba 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. 29 (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. 28, 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. 29B, 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. 29 (b), similarly to FIG. 28, 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 substrate is grounded to the substrate, even if a range of high impedance is generated in the housing due to the grounding, the high impedance range is maintained. Since other grounding points or open points that lower impedance are placed in the housing, unnecessary radiation from the housing can be effectively reduced, which is useful when applied to tuner devices for receiving TV broadcasts and recording / playback. Is.

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, wiring part)
22 Housing 22r, 22s, 22v First grounding point (first place)
22h-22k Legs 22l-22o Holes 22c, 22e-22g Protrusions 22w, 22w', 22wo,
22w1, 22w2,
22x, 22z 2nd grounding point (2nd place)
a Top surface b Front surface c Right side surface d Rear surface e Left side surface k, n Lower side A to F High impedance range (first region)
Lo, L2, L3 Extension line 22op Opening point 23 F type connector (connector part)
24 RF cable (signal cable)
25 Soldering 30 Microcomputer 35 Metal line (extension line)
36 Metal leaf spring 37 Non-grounded pattern (first conductor part)

Claims (14)

A signal processing unit that includes an oscillating unit that outputs an oscillating signal and processes signals with a frequency higher than 2 GHz, and a signal processing unit.
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 first place and the second place, the first region of the housing whose impedance is higher than the reference impedance which is the impedance of the first place by the first place is higher than the reference impedance by the second place. Is arranged at a position overlapping with at least a part of the second region of the housing, which has a low impedance .
The first region is a region in the housing separated from the first location by an odd multiple of 1/4 of the wavelength of the oscillation signal.
The display device is characterized in that the second region is located at a position in the housing at an even multiple of 1/4 of the wavelength of the oscillation signal from the second location. A signal processing unit that includes an oscillating unit that outputs an oscillating signal and processes signals with a frequency higher than 2 GHz, and a signal processing unit.
A display unit that displays images and
A substrate on which the signal processing unit is arranged and having a ground unit and a first conductor unit,
A conductive housing connected to a first portion of the ground portion and a second portion of the first conductor portion is provided.
In the first place and the second place, the first region of the housing whose impedance is higher than the reference impedance which is the impedance of the first place by the first place is higher than the reference impedance by the second place. Is arranged at a position overlapping with at least a part of the second region of the housing, which has a low impedance .
The first region is a region in the housing separated from the first location by an odd multiple of 1/4 of the wavelength of the oscillation signal.
The display device is characterized in that the second region is located at a position in the housing at an odd multiple of 1/4 of the wavelength of the oscillation signal from the second location. The housing is connected to the first location of the ground portion and a third location different from the second location.
The housing has a third region in which the impedance is higher than the reference impedance due to the third location.
Let the wavelength of the oscillation signal be λ.
The first region and the third region overlap at two points, and the distance X between the two points is 0 <X ≦ λ / 10 that satisfies the following conditions.
The display device according to claim 1 or 2. The housing has a rectangular upper portion and a side portion extending from each side of the upper portion and perpendicular to the upper portion.
The first portion is arranged on a side portion extending from the side on the short side of the upper portion.
The display device according to any one of claims 1 to 3 , wherein the second portion is arranged on a side portion extending from the longitudinal side of the upper portion. The display device according to any one of claims 1 to 4 , wherein the first region and the second region are each a plurality of regions. The first location and the second location are each a plurality of locations.
The display device according to any one of claims 1 to 5 , wherein the number of the second location is equal to or less than the number of the first location. The first place is at least two places,
The second place is
The display device according to claim 6 , further comprising one said second region overlapping the first region at least two places. The display according to any one of claims 1 to 7 , wherein the second portion is arranged at a predetermined position on the substrate away from the housing by an extension line connected to the housing. apparatus. The housing is arranged in a predetermined area of the substrate and
The display device according to claim 8 , wherein the second location is arranged in the predetermined area. The display device according to claim 9 , wherein the extension line is a wiring portion arranged on the substrate. The display device according to any one of claims 1 to 10 , wherein the first region or the second region includes a region corresponding to a change range of the wavelength of the oscillation signal. 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 11 , wherein the first region is in the vicinity of the connector portion. 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