JPH0375093B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is designed to be worn by workers engaged in various live line construction works such as power transmission, substation, and distribution, as well as other general construction work, and The present invention relates to a telephone helmet that allows communication between workers and between workers and a control room, etc., while protecting workers.

(Prior Art) Helmets incorporating wireless devices for mutual communication have been known for a long time, as shown in Japanese Patent Application Laid-Open No. 48-30809, but in conventional telephone helmets, the transmitting and receiving circuits are integrated. It was common to have an antenna for both transmitting and receiving purposes installed along the outer surface of the helmet. For this reason, if the sensitivity of the receiver was improved to improve communication performance, the transmitted radio waves would loop around to the receiving side, making it difficult to make good wireless calls. In addition, since the metal antenna is exposed to the outside, it is dangerous to use it for electrical work, and because the distance between the antenna and the human head is small, the capacitance between the antenna and the human head becomes large. Antennas made of wires have large reactance, making it impossible to obtain sufficient antenna gain, and they also have the drawback of not being able to obtain good sensitivity.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and can be safely used for electrical work, and allows wireless communication with high sensitivity even when the output of radio waves is low. It was completed with the aim of making it a helmet that can be used for telephone calls.

(Means for Solving the Problems) The present invention attaches a band-shaped receiving antenna with a length of 1/2 wavelength and a width/length ratio of 0.02 to 0.1 on the inner ear flap side of the helmet body. , a similar transmitting antenna is attached to the opposite side.

(Example) Next, the present invention will be explained in more detail with reference to the drawings. In Fig. 1, 1 is a helmet body made of fiber-reinforced plastic, polyethylene, polycarbonate, etc., and 2 is a helmet body that fixes the helmet to the head. The space formed between the two is provided with a buffer body 3 made of a material with excellent shock absorption performance, such as styrofoam resin. Reference numeral 4 denotes an ear pad protruding from one side of the helmet body 1, and a band-shaped receiving antenna 5 is attached to the inside of the helmet body 1 above the ear pad 4. The receiving antenna 5 is preferably of a dipole type, with a length of 1/2 wavelength and a width/length ratio in the range of 0.02 to 0.1. When installing the antenna inside the helmet, the capacitance becomes large because the antenna and the human head are close to each other.
In a high frequency range such as Hz, the reactance of the antenna must be reduced to achieve tuning between the transmitter/receiver and the antenna. In addition, in the case of a band-shaped antenna, the reactance of the antenna can be reduced in proportion to its width, so in the present invention, the width/length can be reduced.
It was set at 0.02 or more. If this ratio is smaller than this, sufficient tuning cannot be achieved, resulting in a decrease in antenna gain and poor reception sensitivity. On the other hand, if the width is increased beyond this range, the antenna area becomes too large and the capacitance between the human head also increases, making it impossible to tune. A major feature of the present invention is that the dimensions of the antenna are set to optimal values in consideration of the capacitance between the antenna and the human head. It is preferable to use copper foil or aluminum foil for such a receiving antenna 5 in order to match the curved surface of the helmet body 1, and from the viewpoint of weight reduction, it is preferable to use a compact antenna with a thickness of 0.5 mm or less. On the other hand, on the opposite inner side of the helmet body 1, a transmitting antenna 6 having the same dimensions and shape as the above-described receiving antenna 5 is attached. These receiving antennas 5 are connected by coaxial cables to a receiving board 7 attached to the inside of the earmuff 4, and the transmitting antenna 6 is connected to a transmitting antenna embedded inside the buffer 3 at the top of the helmet. It is connected to the board 8 by a coaxial cable. The length of these coaxial cables is most preferably approximately 1/2 wavelength, and they are arranged so that their lengths match each other and do not cross each other.

Reference numeral 9 denotes a pinpoint-oriented microphone attached to the front part of the helmet body 1, and is connected to the transmitting board 8 via a lead wire 11 in a groove 10 formed in the buffer body 3. The heaviest battery is stored in the parts storage section 12 of the cushioning body 3 on the opposite side of the earmuff section 4.
It is mounted inside to balance the weight and prevent fatigue even when worn for long periods of time.

(Function) Items constructed in this way can be worn by workers engaged in various types of live wire construction work and general construction work to protect the workers' heads, as well as between workers and between workers and control rooms, etc. However, in the present invention, a receiving antenna 5 and a transmitting antenna 6 are attached to the inside of the helmet body 1, so unlike a conventional telephone helmet, a metal The antenna is not exposed to the outside, so it can be used during electrical work such as live line construction work. Furthermore, when the antenna is placed close to the human head in this way, the reactance of the antenna becomes large and it becomes difficult to achieve tuning, but in the present invention, the length of the receiving antenna 5 and the transmitting antenna 6 is 1/2. The width/length ratio is the wavelength
Since it was made into a band shape within the range of 0.02 to 0.1,
The reactance of the antenna can be reduced and the antenna gain can be sufficiently increased. Furthermore, in the present invention, the earmuffs 4 of the helmet body 1
Since the receiving antenna 5 is installed separately on one side and the transmitting antenna 6 is installed on the opposite side, the transmitting radio waves do not go around to the receiving side, and the sensitivity of the receiver can be dramatically improved. Since there is no need for an inflow prevention circuit, there is an advantage that the receiver can be made smaller and lighter. In addition to the receiving antenna 5 and the transmitting antenna 6 as in the embodiment, a transmitting board 8,
By embedding the battery, lead wire 11, microphone 9, etc. in the recessed portion of the buffer body 3, it is possible to eliminate the component mounting plate, which has the advantage of reducing the weight of the helmet.

(Effects of the Invention) As is clear from the above description, the present invention has an antenna installed inside the helmet body, so it can be safely used for electrical work, and the dimensions and shape of the antenna are determined as described above. By doing so, the antenna gain can be increased despite the increase in capacitance between the antenna and the human head, and the receiving antenna and transmitting antenna are installed separately on opposite sides to prevent radio waves from crossing over. Combined with this, the sensitivity of calls can be significantly improved even when the output of radio waves is low. Therefore, the present invention is suitable for being worn by workers engaged in electrical work or general construction work, and will greatly contribute to the development of industry as a telephone helmet that has both a head protection function and a telephone communication function. It's large.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention. 1: helmet body, 5: receiving antenna,
6: Transmission antenna.

Claims (1)

[Claims] 1 A band-shaped receiving antenna 5 having a length of 1/2 wavelength and a width/length ratio of 0.02 to 0.1 is attached to the inner ear flap 4 side of the helmet body 1, and a similar transmitting antenna is attached to the opposite side. A telephone helmet characterized by having an antenna 6 attached thereto.