JPH09224274A - Card type radio call receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sensitivity by reducing the influence of reception sensitivity drop caused by a vibrator by setting the fixing position of the vibrator near a short-circuiting point away from a feeding point. SOLUTION: Power is supplied from one corner part A-A' where conductor panels 1 and 2 are confronted, other corner parts B-B' and C-C' are short- circuited by a conductor 4, and a vibrator 5 is arranged near the corner part C-C'. Therefore, the arranging position of the vibrator 5 is set near the corner part C-C' most separated from the feeding point A-A', and that corner part C-C' becomes the point of short-circuiting due to the conductor 4. Therefore, even when the upside conductor panel 1 is electrostatically coupled and short- circuited in high frequency menner by generating stray capacity in the gap, the influence upon an effective antenna loop opening area is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small portable radio device, and more particularly to a thin card type radio paging receiver in which a receiver case also serves as an antenna and which has a vibrator for notifying a call. .

[0002]

2. Description of the Related Art FIG. 1 is a schematic perspective view showing the appearance of a conventional thin card type radio paging receiver. In the figure, 1 is an upper conductor plate, 2 is a lower conductor plate, 3 is an insulating frame, 4 is a short-circuit conductor, 5 is a built-in vibrator, A, A ′,
~, D, D'are corners. In this figure, the display window, select button switch,
Illustration of the mode button switch and the operation switch on the side is omitted. 2. Description of the Related Art Conventionally, an antenna of a card type pager (selective call receiver) has, as shown in FIG. 1, two conductor plates 1 and 2 arranged in parallel with a distance h sufficiently smaller than the wavelength, and insulated between them. It also serves as a radio case in which the frame 3 is arranged. In this conventional example, the length L =
It is a flat rectangular parallelepiped having a width of 80 mm, a width W of 50 mm, and a height (interval) h of 5 mm, and a receiver circuit is incorporated in the case.

A feeding point is provided at an arbitrary position (here, a corner AA 'point) between the two conductor plates 1 and 2 arranged in parallel, and an arbitrary position (here, at another position) on the opposite side. Corner B-
One or both of B ′ and C-C ′) are short-circuited by the short-circuit conductor 4 to form a plate-shaped loop antenna. The dimensions of each part in this example, the feeding position and the short-circuiting position are finally determined by experiments. Further, this loop antenna resonates at about 500 MHz, and in reality, a matching circuit using a capacitor is added to the feeding point to lower the resonance frequency and is used in the 280 MHz band.

[0004]

However, in the above-mentioned conventional selective call receiver, the vibrator 5 is arranged mainly in the vicinity of the path through which the antenna current flows. Since the vibrator 5 is made of a material having a low conductivity in a high frequency band (280 MHz in this case), it acts as a loss body for the antenna current. In addition, the vibrator 5
Is fixed in contact with the lower conductor plate 2, but there is a slight gap between the upper conductor plate 1 and the upper conductor plate 1, and the upper and lower conductor plates 1 and 2 are electrostatically coupled by stray capacitance in the gap. Has a function of short-circuiting at high frequency. Therefore, a part of the antenna high-frequency current flows through the vibrator 5, the effective loop opening area of the antenna becomes small, and the efficiency of the antenna decreases, that is, the receiving sensitivity decreases, which is a practical problem. There is.

An object of the present invention is to provide a card-type radio paging receiver in which the deterioration of the reception sensitivity due to the vibrator as described above is reduced.

In order to achieve the above object, a card type radio paging receiver of the present invention accommodates a receiver circuit and a paging vibrator, and an insulator frame is sandwiched by two rectangular conductor plates from both sides. One of the opposite corners of the other short side that is opposed to the short side is defined as a feeding point in the vicinity of the corner of the opposite short side of the two conductor plates of the receiver case fixed by In a card type radio paging receiver configured to also serve as a loop antenna as a short-circuit point where both corners are short-circuited with a short-circuit conductor, the vibrator is
It is characterized in that it is arranged in a range surrounded by 4/5 of the other short side and 1/2 of the long side.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, since the built-in vibrator is arranged near the short-circuit point far from the feeding point, the antenna opening area approaches the loop opening area of the original radio receiver, The effects of high-frequency short circuits are reduced, and antenna efficiency and reception sensitivity are greatly improved.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a perspective view showing the appearance of an embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals. Two conductor plates 1 and 2 are arranged in parallel at a distance h, and an insulating frame 3 is arranged between them, and these both serve as a radio case and an antenna. In the case of this embodiment, the length L =
It is a flat rectangular parallelepiped having a width of 80 mm, a width W of 50 mm, and a height (interval) of h = 5 mm, and a receiver circuit and a driving vibrator 5 are incorporated in the case.

A feeding point is provided at an arbitrary position on the two conductor plates 1 and 2 arranged in parallel, and a plate-shaped loop antenna is formed by arranging a short-circuit point at another position. It has a structure that operates as a loop antenna. Dimensions L, W, h of each part of the antenna of this embodiment,
The position of the feeding point and the position of the short circuit point are determined by the desired antenna characteristics. The distance h between the two conductor plates 1 and 2 is related to the antenna gain, and the antenna gain is improved as the value is sufficiently smaller than the wavelength and the antenna gain is improved. .

In the embodiment shown in FIG. 2, power is supplied from one of the opposing corner portions AA 'of the two conductor plates 1 and 2, and the other corner portions BB' and CC 'are conductors. This is an example in which the vibrator 5 is arranged near the corner C-C 'by being short-circuited by 4. That is, the arrangement position of the vibrator 5 is the feeding point A-
It is set in the vicinity of the corner CC ′ that is farthest from A ′, and the corner CC ′ is a short-circuit point by the short-circuit conductor 4. In this way, if the vibrator 5 is arranged along the side farthest from the feeding point AA ′, even if stray capacitance is generated between the vibrator 5 and the upper conductor plate 1 and electrostatically coupled, and short-circuited at high frequency, There is little effect on the effective antenna loop aperture area. In this case, the corner short-circuit points C-C 'and D-D'
Both may be short-circuited, only one may be short-circuited, or both may not be short-circuited, and three or more points may be short-circuited on this side.

FIG. 3 is a perspective view showing an application example of the present invention, in which the range of the vibrator fixing position where the effect of the present invention is obtained is shown by hatching. L'is 1/2 of the total length L.
That is, it is a range from the short side facing the short side including the corner portion AA ′ of the feeding point to ½ of the long side length L of the case. The width W'is 4/5 of the total width W, and is a range of W'on the short side from the corner CC 'which is farthest from the corner AA' of the feeding point.

In the above description, for the sake of clarity, it has been explained that the short-circuit between the two conductor plates 1 and 2 arranged in parallel is performed by the conductor 4 or the like. The same effect can be obtained when a short-circuit is made with a strip-shaped conductor having a.

In the embodiment of FIG. 2, the receiving sensitivity is improved by 0.5 to 1.0 dB as compared with the case of the conventional example of FIG. This value is almost the same as when the vibrator 5 is removed.

[0014]

As is apparent from the above description, according to the present invention, if the fixed position of the vibrator is set near the feeding point and set near the short-circuit point, the influence of the decrease in the receiving sensitivity due to the vibrator is reduced. An extremely enormous effect that a sensitive wireless receiver can be realized can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing the appearance of a conventional card type radio paging receiver.

FIG. 2 is a schematic external perspective view showing an embodiment of the present invention.

FIG. 3 is a perspective view showing an application example of the present invention.

[Explanation of symbols]

 1, 2 conductor plate 3 insulating frame 4 short-circuit conductor 5 vibrator h spacing A, A'feeding point

Claims (2)

[Claims] 1. A receiver case in which a receiver circuit and a calling vibrator are housed and an insulator frame is sandwiched and fixed by two rectangular conductor plates from both sides, and the two conductor plates face each other. A loop antenna is used as a short-circuit point in which one or both of the corners of one of the two short sides facing each other in the opposite relationship to the short side are short-circuited with a short-circuit conductor, with the vicinity of the corner of one short side being the feeding point In a card type radio paging receiver configured to be shared, the vibrator is arranged in a range surrounded by 4/5 of the other short side and 1/2 of the long side. Radio call receiver. 2. The card-type radio paging receiver according to claim 1, wherein the vibrator is arranged near the short-circuit point.