JPH0742191U - Transceiver for wireless communication device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a transceiver device for a communication device capable of improving the shield effect. A double-sided structure in which a shield plate 40 covers a region of the printed circuit board 20 housed in a shield case 10 on which a radio signal transmission / reception circuit is mounted and which corresponds to a voltage-controlled oscillator of a reception circuit. It has a shield structure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a transceiver for a wireless communication device, and more particularly to an improvement for suppressing spurious emission in a compact transceiver for a wireless communication device such as a cordless telephone device.

[0002]

[Prior art]

 As an example of this type of transceiver for a wireless communication device, a case of a cordless telephone device will be described with reference to FIG. In FIG. 7, this transmitting / receiving device has a receiving circuit 70 for processing a voice signal received through the antenna ANT and a transmitting circuit 90 for transmitting the voice signal. To briefly explain the configuration, the receiving circuit 70 includes a surface wave filter 71, an RF amplifier 72, a bandpass filter 73, a first local frequency signal supplied from a receiving side voltage controlled oscillator 74 via an amplifier 75, and a bandpass filter. The first mixer 76, the crystal filter 77, the IF amplifier 78, the crystal oscillator 79, the amplifier 80, the FM demodulator 81, the low-pass filter 82, and the level adjustment for mixing the signal from 73 to obtain the first intermediate frequency signal It includes a container 83.

The FM demodulator 81 mixes the second local frequency signal supplied from the crystal oscillator 79 via the amplifier 75 with the first intermediate frequency signal to obtain a second intermediate frequency signal. 84, an IF amplifier 85, and a detector 86 for extracting a sound signal. As a circuit external to the FM demodulator 81, a filter 87 is connected between the second mixer 84 and the IF amplifier 85, and a regulator 88 is connected.

On the other hand, the transmission circuit 90 includes a low-pass filter 91, a frequency deviation adjuster 92 for adjusting the frequency deviation width of an audio signal, a transmission side voltage controlled oscillator 93, a buffer amplifier 94, a power amplifier 95, It includes a first RF amplifier 96, a second RF amplifier 97, and a bandpass filter 98.

In addition, a PLL circuit 100 is provided as a circuit common to the receiving circuit 70 and the transmitting circuit 90, and a low-pass filter 101 is provided between the PLL circuit 100 and the receiving-side voltage-controlled oscillator 74, and a PLL circuit 100 is provided. The low-pass filters 102 are connected to the transmission-side voltage-controlled oscillator 93. SW1 and SW2 are switches, and are regulators for supplying 103 + B power. In the following description, the portion from the antenna ANT to the first mixer 76 on the receiving circuit 70 side and the portion from the buffer amplifier 94 to the antenna ANT on the transmitting circuit 90 side will be referred to as an RF (Radio Frequency) unit. .

Further, the present apparatus has a voice signal input terminal T 1 as a signal input / output terminal, a transmission side voltage controlled oscillator switch terminal T 2 for supplying an ON / OFF control signal to the switch SW 1, and a transmission in the PLL circuit 100. Side PLL lock output terminal T3, clock signal input terminal T4, data signal input terminal T5, ground terminal T6, audio signal output terminal T7, ground terminal T8, transmitter side for supplying ON / OFF control signal to switch SW2 RF amplifier switch terminal T9, receiving side PLL lock output terminal T10 in PLL circuit 100, power supply input terminal T11, enable signal input terminal T12 in PLL circuit 100, noise squelch output terminal T13, S meter output terminal T14, RF input / output 17 terminals: T15, ground terminals T16, T17 Equipped with a force terminal.

In the case of a cordless telephone device, the channel pair transmission / reception frequencies of the master unit and slave unit are: transmission frequency (1 to 80 CH) 930.0125 to 931.998 75 MHz, reception frequency (1 to 80 CH) for the master unit. It is 885.0125-8866.9875 MHz. On the other hand, for the slave unit, the transmission frequency is 885.0125-886. The reception frequency is 9387525 to 931.9875 MHz, the first intermediate frequency is 64.45 MHz, and the second intermediate frequency is 450 kHz.

A transmitter / receiver having the above-described configuration and standard is well known, and therefore the description of the operation will be omitted.

By the way, this type of transmitter / receiver is usually used indoors, and in that case, spurious radiation from each of the above-mentioned parts, that is, unnecessary radiation, poses a problem. In other words, such unnecessary radiation adversely affects other electronic devices indoors, such as malfunction and noise, and thus it is required to be suppressed as much as possible.

[0010]

[Problems to be solved by the device]

 Therefore, the circuit shown in FIG. 7 is mounted on a printed circuit board, and the printed circuit board is housed in a shield case to suppress unnecessary radiation. However, in recent years, especially in foreign countries, the standards regarding the suppression of unwanted radiation have become stricter, and it is no longer possible to meet the requirements of the standards only with the shield case as described above.

Therefore, an object of the present invention is to provide a transmitter / receiver for a communication device capable of improving the shield effect.

[0012]

[Means for Solving the Problems]

 The present invention relates to a transceiver device for a wireless communication device, which comprises a shield board housing a board on which a radio signal reception circuit and a transmission circuit are mounted, and a voltage-controlled oscillator on the front surface side of the board It is characterized by a double shield structure by covering the corresponding area with a shield plate.

[0013]

【Example】

 An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the transmitter / receiver circuit shown in FIG. 7 mounted on a printed circuit board 20 and housed in a shield case 10. FIG. 2 is a view of the printed circuit board 20 viewed from the back side. In addition, in this figure, only the representative parts constituting the transmission / reception circuit are shown, and other parts and circuit patterns are not shown. FIG. 3 shows a shield case 10, in which a partition wall 11 is formed for each circuit that requires a shield. The partition wall 11 is usually stamped and formed integrally with the shield case 10, and is formed by bending as shown in FIG.

Blocks A to K (excluding I) shown in FIG. 1 correspond to the blocks A to K shown in FIGS. 3 and 7, respectively. The block A includes a low-pass filter 91, a frequency deviation adjuster 92, a transmission side voltage control oscillator 93, and a buffer amplifier 94 in the transmission circuit 90. For example, the audio input adjustment volume 21 and the transmission side voltage control oscillator 93 A frequency adjusting volume 22 is mounted.

The block B includes the power amplifier 95 and the first and second RF amplifiers 96 and 97 in the transmission circuit 90. For example, the transmission output adjusting volume 23 that constitutes the power amplifier 95 is mounted. . On the other hand, the bandpass filter 98 in the transmission circuit 90 includes a plurality of coil components to form a filter, and these coil components need to be individually shielded so that they are separately mounted in three blocks C, D, and E. It Here, the coil component 24 is mounted on the block C, the coil component 25 is mounted on the block D, and the coil components 26 and 27 and the terminals T15 to T17 are mounted on the block E, respectively.

In the receiving circuit 70, the filter 28 that constitutes the surface wave filter 71 is mounted in the block F, and the blocks G and H include the RF amplifier 72, the bandpass filter 73, and the first mixer 76. The coil components 29 and 30 are mounted by being partitioned by the partition wall 11. Further, the block J includes a receiving side voltage controlled oscillator 74, and the frequency adjusting volume 31 thereof is mounted.

Further, in the block K, the remaining circuits of the receiving circuit 70 are mounted, and terminals T1 to T5 and T7 to T14 are mounted at positions opposite to the terminals T15 to T17. As an example of the mounted components in the block K, filters 32a and 32b constituting the crystal filter 77 and its adjuster 33, FM detection IC 34 constituting the detector 86, and audio output adjusting volume constituting the level adjuster 83 are shown. 35, a squelch adjusting volume 36, a ceramic filter 37, a package 38 including a crystal oscillator 79 and its temperature compensating circuit, an IC package 39 for the PLL circuit 100, etc. are mounted.

As shown in FIG. 4, the transmission / reception circuit mounted on the printed circuit board 10 as described above is covered by the upper cover 12 and the lower cover 13 which form the shield case 10 from above and below, and is shielded. To be done. Reference numerals 14 are claws for mounting the transmitting / receiving apparatus on the main circuit board, and are provided near the four corners of the shield case 10. The plurality of holes 15 provided in the upper cover 12 are for allowing adjustment of the above-mentioned various volumes and adjustment parts on the printed circuit board 10 without removing the upper cover 12. . That is, this kind of adjustment work is performed by inserting a jig such as a driver into the groove of the adjustment component through the hole 15.

By the way, in the present invention, in addition to the shield by the shield case 10 described above, in order to improve the effect of suppressing spurious radiation, a specific block among the blocks A to K described above is shielded by a shield plate. It enables double shield.

That is, regarding the front surface side of the printed circuit board 10, referring to FIG. 1, the entire area of the block J in which the receiving side voltage controlled oscillator 74 is mounted is covered with the shield plate 40. The shield plate 40 is provided with a hole 40-1 for adjusting the frequency adjusting volume 31.

Referring to the back surface side of the printed circuit board 10, referring to FIG. 2, all of the blocks B to C, D, E, F, G, H, and J and part of the block K are referred to. The shield plate 41 covers a part of the block A, more specifically, the transmission side voltage controlled oscillator 93, by the shield plate 42. The round holes and the square holes provided in the shield plate 41 avoid contact with components (not shown) mounted on the back surface of the printed circuit board 20 and prevent the components mounted on the front surface of the printed circuit board 20 from contacting. It is provided in order to avoid contact with the protruding portion when the terminal protrudes to the back surface side of the printed circuit board 20. Further, as for the portion to be shielded by the shield plate 41, in the case of the receiving circuit 70, it may be between the surface wave filter 71 and the first mixer 76, that is, the blocks F, G and H in FIG. May be between the transmission side voltage controlled oscillator 93 and the bandpass filter 98, and may be the RF section in the whole transmitting / receiving circuit.

As described above, by shielding a portion having a large amount of spurious radiation with the double shield structure, the effect of suppressing spurious radiation can be further enhanced as compared with the shield having only the shield case 10.

In addition to the double shield structure as described above, in the present embodiment, the filter in the RF section, here the bandpass filter 73 in the receiving circuit 70, is divided into the coil component 29 and its peripheral circuit by the partition wall 11-1. And a block G on which the coil component 30 and its peripheral circuit are mounted are shielded by dividing the band pass filter 98 in the transmission circuit 90 by the partition walls 11-2 and 11-3. 24 Shielded by partitioning into a block C on which the circuit 24 and its peripheral circuits are mounted, a block D on which the coil component 25 and its peripheral circuits are mounted, and a block E on which the coil components 26 and 27 and their peripheral circuits are mounted. We are trying to improve the effect.

In the present embodiment, the shielding effect is further improved by further improving the ground structure of the mounting component having the shield plate and the metal case. The first example is, with reference to FIGS. 1, 4 and 5, an upper cover 12 forming a shield case 10 and two cut-and-raised claws formed by two cut-and-raised parts at a position corresponding to the shield plate 40. Is formed. The cut-and-raised claw 16 is cut and raised toward the lower surface side, that is, inward of the shield case 10 so that the cut-and-raised claw 16 contacts the shield plate 40 when the upper cover 12 is attached to the main body of the shield case 10. I have to .

According to such a structure, the shield plate 40 is connected to the surrounding partition wall 11 by soldering or the like, so that not only the earth connection with the shield case 10 main body is performed through the partition wall 11. By directly contacting the upper cover 12, the grounding connection with the main body of the shield case 10 is performed, so that the shield effect is improved. In other words, in order to improve the shield effect by grounding a portion such as the shield plate 40 near the center of the printed circuit board, simply connecting it to the main body of the shield case 10 via the partition wall 11 will increase the distance. However, this is not sufficient because the length becomes longer, but improvement can be achieved by directly connecting the shield plate 40 to the shield case 10 as in the present embodiment. Of course, such a structure may be applied to the shield plates 41 and 42.

A second example of the ground structure improvement is to refer to FIGS. 1 and 6 between the metal case of the regulator 33 and the partition wall 11 which constitute the crystal filter 77 in the block K. By connecting with the soldering portion 17, the metal case of the adjuster 33 is grounded to improve the shield effect.

As described above, in the present embodiment, the back side of the printed circuit board 20 corresponding to the RF section and the transmission side voltage controlled oscillator 93 in the reception circuit 70 and the transmission circuit 90 and the reception side voltage controlled oscillator 74. The shield effect can be improved by forming the double shield structure on the surface side of the printed circuit board 20 corresponding to the above. Among the shield plates that make up the above double shield structure, the shield plate near the center of the printed circuit board and the ground structure for mounted components with a metal case have also been improved by adding improvements to the shield structure. The effect can be improved. Of course, in the case of a cordless telephone, the above structure is applied to both the base unit and the handset.

[0028]

[Effect of device]

 As described above, according to the present invention, the area on the front side of the printed circuit board, which is housed in the shield case and on which the radio signal transmission / reception circuit is mounted, and which corresponds to the voltage controlled oscillator in the reception circuit. The shield effect can be improved by covering the with a shield plate to form a double shield structure. As a result, spurious emission can be suppressed, and it is possible to provide a transmission / reception device most suitable for a wireless communication device such as a cordless telephone in which there is an increasing demand for improvement in suppression of spurious emission.

[Brief description of drawings]

FIG. 1 is a view of a transmitter / receiver to which the present invention is applied, viewed from the front side of a printed circuit board.

FIG. 2 is a view of the transmitter / receiver shown in FIG. 1 viewed from the back surface side of a printed circuit board.

FIG. 3 is a top view of the main body of the shield case used in the present invention.

FIG. 4 is a view of a shield case used in the present invention as seen from above (FIG. A), side (FIG. B), and front (FIG. C).

5 is a perspective view of a part of the upper cover of the shield case shown in FIG. 4 as viewed from the inside.

6 is a perspective view for explaining an example of a grounding structure between a mounting component having the metal case shown in FIG. 1 and a partition wall.

FIG. 7 is a block diagram for explaining an example of a transmission / reception circuit of a cordless telephone to which the present invention is applied.

[Explanation of symbols]

 10 shield case 11 partition wall 12 upper cover 13 lower cover 16 cut-and-raised claw 17 soldering part 20 printed circuit board 21 audio input adjustment volume 22, 31 frequency adjustment volume 23 transmission output adjustment volume 24, 25, 26, 27 , 29, 30 Coil parts 28 Filter 32a, 32b Filter 33 Regulator

Claims (1)

[Scope of utility model registration request] 1. A transmitter / receiver for a wireless communication device, comprising a substrate on which a receiver circuit and a transmitter circuit for a radio signal are mounted, which is housed in a shield case, and a voltage controlled oscillator in the receiver circuit on the front surface side of the substrate. A transmitter / receiver for a wireless communication device, which has a double shield structure by covering a corresponding area with a shield plate.