JPH01138823A - Portable wireless transmitter - Google Patents

Abstract

PURPOSE:To reduce the spurious radiation remarkably by mounting an oscillation circuit part provided with a loop antenna and a frequency multiplication circuit to an insulation board and providing a conductive shield to a part other than the loop antenna onto other side. CONSTITUTION:A double side copper clad laminating plate adhered with copper foil is used to both front and rear sides of an insulation board, the one side is subject to etching processing to form the circuit pattern, a required electric component is mounted and the oscillation circuit part 10 is formed together with the loop antenna 13 and a conductive shield plate 1 is formed to the rear side while the copper foil of the part except a part 6 corresponding to the part formed with the antenna 13. Through the constitution above, if a high frequency signal caused by the oscillation circuit and the multiplication amplifier circuit part of the circuit 10 is made incident in the shield plate 1, an eddy current is induced in the shield plate 1 by the high frequency magnetic field and a magnetic field to block the eddy current is produced, then the incoming magnetic field is cancelled and the heat loss due to the resistance of the plate 1 caused by the current flowing to the plate 1 is attenuated. Thus, the spurious radiation is reduced considerably.

Description

[Detailed description of the invention] [Technical bone! ! P1 The present invention relates to improvements in portable wireless transmitters.

[Background technology] Recently, wireless transmitters have been developed that use weak radio waves to notify the occurrence of an emergency when an elderly person who requires nursing care walks alone or a sick person leaves a caregiver. .

FIG. 12 is a diagram showing an example of its use. In the figure,
When m, such as a bedridden old man, is lying on the bed, the wireless transmitter a is housed in a holder near the bed, and in this state, no signal is transmitted from the wireless transmitter a. However, old man M takes wireless transmitter a out of the holder and moves it away from the bed.
If an emergency situation occurs while you are carrying the device, and you operate the trigger switch, an emergency signal will be transmitted as a radio wave signal, detected by the receiver, and alarm means such as housing information board C will sound. to notify the occurrence of an emergency situation.

By the way, to explain such a conventional portable wireless transmitter, FIG. 11 shows this structure.
The lid cover 300 can be removably attached as a separate piece to a part of the upper case 200 in which the push switch 201 is provided, and when the lid cover 300 is removed, the upper case 200 and the main body 500 are exposed. It has a structure in which a battery accommodating part and various switches 401 and 402 are provided in a part of the case, and the lid cover 300 has its retaining convex part 301 in a recess 203 provided in a corresponding part of the upper case 200. They are integrally connected by engaging and can be removed by releasing this engagement.

However, creating a wireless transmitter with such a three-piece outer shell increases the thickness of the main body itself, increases the number of parts, and causes problems such as some of the parts may be lost during use.

In addition, when considering the intended use of such portable wireless transmitters, they are often used in environmental conditions with a lot of vibration and shock, so in order to obtain frequency stability of the radio waves to be transmitted, it is necessary to use a crystal oscillator. Although a crystal oscillation circuit using a oscillator is preferably employed, an inexpensive crystal oscillator with a frequency band lower than the oscillation frequency is used. For this purpose, the oscillation frequency by the crystal oscillator is frequency multiplied to achieve the desired
A method of obtaining frequency is commonly used.

However, frequency multiplication produces many harmonic components by distorting the oscillation frequency of the crystal oscillator itself, and the desired harmonic is selected from among them using a resonant circuit, so the wiring pattern of the frequency multiplication circuit is A large number of harmonics and subharmonics other than the intended transmission frequency are radiated from the antenna and components, and the harmonics and subharmonics generated during frequency multiplication are transmitted to other electrical devices, such as television receivers and radio receivers. This will cause interference to the aircraft. 1. Recently, from the perspective of preventing radio wave interference, not only the transmission frequency of communication equipment but also the
Legal regulations regarding harmonics and subharmonics are becoming extremely strict, and the absence of such spurious signals in portable wireless transmitters is an issue that must be resolved as soon as possible.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides a portable wireless oscillator that can reduce a large number of harmonics and subharmonics generated from a frequency multiplier circuit with a simple configuration and has less spurious radiation. The purpose is to provide.

[Disclosure of the Invention] A portable wireless transmitter of the present invention proposed to achieve the above object has a transmitting circuit section having a loop antenna and a frequency multiplier circuit mounted on one side of an insulating substrate, and a transmitting circuit section having a loop antenna and a frequency multiplier circuit mounted on one side of the insulating substrate. The present invention is characterized in that it includes a thin plate main body having a conductive shield plate provided in a portion other than the loop antenna portion.

Example The present invention will be described in detail below with reference to the drawings.

1 and 2 are exploded perspective views showing one embodiment of the wireless transmitter of the present invention, with FIG. 1 being a view seen from the surface, and FIG.
The figure is a view from the back.

As shown in these figures, the portable wireless transmitter A of the present invention has three operation switches 3a in three recesses 20 formed on the surface of a thin card-shaped main body case 2.
3c, and has a structure in which the battery case 4 can be removably inserted.

The three pushbutton operation switches 3a to 3c are operated depending on the purpose of the call, for example 3a is for mere communication.

3b is for notification when going out of the transmission area, 3c is for emergency use, etc. 9 The back structure of the main body case 2 is as shown in FIG. , and then insert and remove the battery case 4 into the space 21 formed in the main body case 2.

Such a space 21 provided for accommodating a battery case
have locking claws 21a, 21. a is formed, and a corresponding claw 4 provided at the tip of the leg portion 41.41 of the battery case 4.
In the example shown in FIG. 0, the battery case 4 is provided with a recess 40 corresponding to the circular mercury battery 5, and the mercury battery 5 is fitted into this part.

A conductive plate 42 having a plurality of small protrusions shaped like comb blades is placed on the recess 40 that accommodates the battery.
The small protruding piece 2 is located in the space 21 of the main case 2 where the battery case 4 is located.
[The conductive pattern provided on the circuit board 6 side]
5 to selectively turn on and off the terminals of the IC element 15 mounted on the circuit board 6 to set the house code.

FIG. 3 shows a concavity showing the component side of the circuit board 6, where 1] is an oscillation circuit section, 12 is a frequency multiplication and power amplification circuit section, 13 is a loop antenna, and 14 is an LED for operation display. , 15 is a pattern in which the small protrusions of the conductive plate 42 selectively come into contact to set a house code, and 16 is a pattern other than the transmitting circuit section, frequency multiplication and amplification circuit section, and loop antenna section of this wireless oscillator. It shows an IC with integrated circuits.

FIG. 4 is a view of the opposite side of the component surface of the circuit board 6, and the area other than the portion corresponding to the loop antenna 13 is f! of the circuit board 6. Foil 1 is left as is. In this way, the transmitting circuit section 10 is formed on the circuit board 6,
FIG. 5 shows the configuration of the transmitting circuit section as an electric circuit.

This oscillation circuit section 10 includes an oscillation circuit 11, a frequency multiplication section 1
2 and an antenna section 13. In the figure,
Ql is a transistor of a crystal oscillation circuit, and this transistor Q1 is directly biased by resistors R1 and R2, and is subjected to negative DC feedback by a resistor 173.

It also oscillates at a frequency determined by the crystal oscillator X, coil L1, and capacitor Ct, but in order to keep the oscillation stable,
Positive feedback is provided by capacitor C2, and capacitors C3 and C
4. The amount of negative feedback is determined by the coil L2 to maintain stable oscillation. The output of the oscillation circuit section 11 is applied to the transistor Q2 biased by the resistors R4 and R5 through the capacitor C6, and the harmonics of the frequency of the resonant circuit formed by the coil L3 and the capacitor C7 are selectively amplified and sent to the capacitors C8 and C10. is supplied to the loop antenna through. Here, the parallel resonant circuit formed by the capacitor C9 and the coil L4 is tuned to the target oscillation frequency, and has a low impedance for other frequencies.
It acts as a filter to remove interference waves. Further, the capacitor C1l connected to the loop antenna causes resonance between the inductance component of the loop antenna and the capacitor C1l, thereby increasing radiation efficiency.

In the case of a wireless transmitter having such a circuit board 6 as a thin plate main body, high frequencies generated from the oscillation circuit 11 and the multiplication amplifier circuit section 12 of the transmitting circuit section 10 formed on the surface are incident on the conductive shield plate 1. In this case, this high-frequency magnetic field induces an eddy current in the conductive shield plate 1, and a magnetic field is generated that tries to block this eddy current, so the incoming magnetic field is canceled out, and the R electric shield due to the current flowing through the conductive shield plate 1 is canceled. Heat loss due to the resistance of the plate also contributes to attenuation.

According to electromagnetic theory, the shielding effect of a floating conductive plate such as the conductive shield plate 1 in the present invention is that when electromagnetic waves reach the surface of a conductor, part of it is reflected by the surface of the conductor, and other electromagnetic waves are reflected. It has been shown that radio waves are absorbed inside a conductor, and are accompanied by attenuation in both cases.When a radio wave is incident on an insulated conductive shield plate, in addition to the loss due to reflection and absorption, the back electromotive force The radio waves will be attenuated due to the loss of resistance.

FIG. 6 is a spectrum diagram showing the oscillation frequency and electric field strength of spurious radiation when the conductive shield plate is not provided, and FIG. 7 is a spectrum diagram when the shield plate is provided. From the figure, it is clear that the conductive shield plate of the present invention can reduce spurious radiation.

FIG. 8 shows an example of manufacturing a thin plate main body, which is the main part of the present invention.

In the example of FIG. 8, Table 2 of the insulating substrate. A double-sided copper-clad laminate with copper foil pasted on both sides is used, and one side is etched to form a circuit pattern, and necessary electronic components are mounted to form the transmitting circuit section 10 into a loop antenna. 13 (see figure (a)), but a conductive shield plate is formed on the back side of the insulating substrate, leaving the copper foil on the front side except for the part where the loop antenna 13 is formed (see figure (b)). (see figure)).

FIG. 9 shows the process of forming the thin plate body of the present invention using a single-sided copper-clad laminate.

The copper foil attached to one side of the laminate is etched to form the transmitting circuit section 10 and the loop antenna 13, as in the case of FIG. It is formed by adhering another copper foil to the portion of the surface other than the loop antenna 13 on which no copper foil is attached.

FIG. 10 is a diagram illustrating an example of use of the wireless transmitter A of the present invention.

When an elderly person walking alone or a sick person who is away from a caregiver carries it, and an emergency situation arises and the button 3C is pressed, a radio wave signal with a house code added is generated in the transmitting circuit section IO. It is radiated in the form of a radio wave signal from the loop antenna inside it. In this case, the radio signal is transmitted using, for example, the FSK method, and the radiated radio signal is received by the receiver B and sent to a host computer (not shown) or the like, where necessary measures are taken.

In the wireless transmitter of the present invention having such a thin plate main body, the surface of the thin plate main body to which the conductive shield plate is attached is used as the outer surface of the transmitter, and a custom-packed sticker is affixed to that surface. If you print S on it, you can use it as a nameplate, and with something like this f3, you can get an even thinner wireless transmitter.

[Effects of the Invention] According to the present invention, it is possible to significantly reduce spurious radiation, which has been a problem in wireless transmitters using a frequency multiplication method, and as a result, it is possible to increase the power of the target transmission frequency to the regulated value. can be realized, and the radio wave transmission distance of the portable wireless transmitter is significantly improved.

[Brief explanation of the drawing]

Figure 1 is a front view of an embodiment of the wireless generator (i) of the present invention, Figure 2 is an exploded perspective view of the device as seen from the back, and Figure 3 is a main part of the present invention mounted on a thin plate main body. FIG. 4 is a diagram showing the conductive shield plate formed on the thin plate body, FIG. 5 is a circuit diagram of the transmitting circuit section, and FIGS. 6 and 7 are: FIGS. 8 and 9 are explanatory diagrams of the spurious radiation reduction effect according to the present invention, and FIGS. 8 and 9 are manufacturing process diagrams of the thin plate main body. FIG. Fig. 12 is an explanatory diagram of the structure of a portable wireless transmitter, and an example diagram of its use. ) 10... Transmission circuit section 12... Multiplication amplifier circuit section 13... Loop antenna

Claims (4)

[Claims] (1) A thin plate body comprising a transmitting circuit section having a loop antenna and a frequency multiplier circuit mounted on one side of an insulating substrate, and a conductive shield plate provided on the other side of the insulating substrate except for the loop antenna section. A portable wireless transmitter characterized by: (2) A patent in which the insulating substrate has a circuit pattern formed by etching a double-sided steel-clad laminate, and the conductive shield plate is formed by leaving the copper foil surface of the copper-clad laminate intact. A portable wireless transmitter according to claim 1. (3) The insulating substrate has a circuit pattern formed by etching a single-sided copper-clad laminate, and the conductive shield plate has another conductive layer on the surface of the copper-clad laminate on which the steel foil surface is not formed. Claim 1, which is formed by pasting a plate.
Portable wireless transmitter as described in section. (4) The portable wireless transmitter according to claim 2 or 3, wherein the shield plate is formed as a name plate exposed on the outer surface of the wireless transmitter.