JPS5911212B2 - Optical signal transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical signal that reduces the transmission loss of a leading ring that optically transmits a signal output by operating a steering switch provided on a steering wheel in order to control a vehicle load. Regarding transmission equipment.

The applicant of this patent has proposed that a control signal, as shown in FIG. A vehicle load control device for controlling the vehicle load was proposed in a patent application filed on the same date as this patent application.

That is, FIG. 1 shows this vehicle load control device, and the switch board of the steering wheel 13! 11 steering switches 1Ta, 1Tb provided in 513a
,...1Tk and steering switch 1Ta
, Ilb, . . . 1 An encoder 10 circuit 21 which inputs switch information output by the operation of Tk and outputs a pulse encoded signal corresponding to each switch, and a circuit 21 which inputs the pulse encoded signal. , for example, an electro-optical conversion circuit 22 that outputs an optical signal from a light-emitting element 22a made of a light-emitting diode, and an electro-optical conversion circuit 22 that transmits an optical signal, for example, has a high light transmittance,
Acrylic resin, U polymer, and high strength
A leading ring 23 made of poly 15 carbonate or the like, which receives an optical signal from the leading ring 23 and converts it into an electrical signal, for example.
A light receiving element 24 such as an infrared photodiode, an amplifier circuit 25 that amplifies the converted electrical signal, a threshold circuit 26 that cuts the amplified signal at a certain level and shapes it into the original pulse waveform, and the threshold circuit 26 outputs a decoder circuit 27 that decodes a pulse encoded signal to determine which steering switch has been pressed; and a decoder circuit 27 that receives a drive signal output based on the determination of the decoder circuit 27 and drives a selected switch of a corresponding load. The drive circuit 28 has a drive circuit 28 that performs the following steps.

Eleven steering switches 17a, 17b provided on the switch board 13a of the steering wheel 13
, . . . An example of the command content (switch information) of 1rk and the code string representing it is as follows.

In the above configuration, for example, when the steering wheel switch 17d is pressed to select three radio channels,
The encoder circuit 21 inputs the switch information and outputs a transmission code including the code string ("0", "1", "0", "0") shown in the previous table.

This is input to the photoelectric conversion circuit 22, which drives the light emitting element 22a, and the light emitting element 22a outputs an optical signal. Since the converted optical signal propagates inside while reflecting off the wall surface of the light guide ring 23, the light receiving element 24 receives the output light of the light guide ring 23 regardless of the steering angle of the steering wheel 13 and generates electricity according to the received light level. Output a signal. This electrical signal is amplified by an amplifier circuit 25, and a threshold circuit 26 cuts out signals above a predetermined level and outputs the shaped original pulse encoded signal. This pulse signal is input to the decoding circuit 27, where it is decoded to detect that the steering switch 17d has been pressed. With this detection, the radio's 3
Drive circuit 28 assigned to select channels
A control signal is output to the drive circuit 28, and the drive circuit 28 is turned on to switch the channel selection state, and three channels are selected. FIG. 2A shows a light guide ring 23 provided on the steering wheel 13 and a light emitting element 22 embedded in the light guide ring 23 for inputting optical signals to the light guide ring 23.
The opening in FIG. 2 shows a cross section of the light guiding ring 23, and the upper surface 23a is mirror-finished by, for example, applying white paint or vapor depositing silver or aluminum.
It has both inner and outer side surfaces 23b and 23c, and a lower surface 23d from which an optical signal propagating inside is output.

In the above configuration, the optical signal output from the light emitting element 22a is input to the light guide ring 23, propagates inside the ring, outputs from the lower surface 23d which is the light output surface, and is connected to the light receiving element provided on the steering post below. Enter.

By transmitting the optical signal through this optical guide ring 23, the first
The operations described in the figure are realized. However, according to the configuration of this light guide ring 23, for example, from the point P to the outer surface 23b
The optical signal (arrow A1) that travels to the inner surface 23c is reflected as it is and proceeds to the inner surface 23c (arrow A,), and propagates inside the light guide ring 23 while repeating such reflection internally. The signal is attenuated internally without being output from 23d.

Therefore, since transmission loss increases, it becomes necessary to increase the output light amount of the light emitting element and the light receiving ability of the light receiving element accordingly. However, in order to increase the output light amount of the light emitting element,
A large current must be drawn through a slip ring to which it is difficult to supply a large current, and since a large current is supplied to the light emitting element, the operating temperature range is limited due to temperature rise. Furthermore, in order to increase the light-receiving ability of the light-receiving element, it is necessary to use one with high sensitivity, which increases the cost.Also, if you try to solve this problem by increasing the amplification factor of the amplifier circuit, noise will increase. The signal is also amplified, resulting in a decrease in the S/N ratio. The present invention has been made in view of the above, and is aimed at reducing the transmission loss of the light guide ring that optically transmits signals for controlling vehicle loads, and increasing the amount of light output from the light output surface. The present invention provides an optical signal transmission device whose outer and/or inner surfaces are curved or tapered.

That is, the optical signal transmission device according to the present invention includes: a light emitting circuit that outputs an optical signal according to a signal output by each operation of a plurality of steering switches provided on a steering wheel; an optical signal output surface; an optical guide ring having a tapered or curved guide surface that guides an optical signal propagating through the optical signal output surface, and inputs the optical signal output from the light emitting circuit and outputs it from the optical signal output surface. and a light receiving circuit that receives the optical signal output from the light guide ring and outputs a signal corresponding to the optical signal for controlling a vehicle load.

The optical signal transmission device according to the present invention will be explained in detail below.

FIG. 3A shows a first embodiment of the present invention, which includes a steering wheel 13, an upper surface 23a and both inner and outer side surfaces 23b, 23c, which are fixed to the steering wheel 13 and are mirror-finished if necessary. Lower surface 2 which becomes the light output surface
3d, a light emitting element 22a that inputs an optical signal to the light guide ring 23, and a steering post 3.
0 and has a light receiving element 24 that receives an optical signal output from the lower surface 23d of the light guide ring 23.

The outer surface 23b of the light guiding ring 23 is a tapered surface having an angle δ, as shown at the mouth. In the above configuration, the optical signal output from the light emitting element 22a propagates inside the light guide ring 23, and the light receiving element 24 receives the optical signal output from the lower surface 23d of the light guide ring 23. Light receiving element 2
Reference numeral 4 outputs an electric signal corresponding to the received light signal to a subsequent control circuit (not shown) to control the vehicle load. Light guiding ring 2
For example, even if the optical signal propagating through the inside of 3 travels from the point P to the outer surface 23b (arrow A1), since this surface 23b is a tapered surface, it will be reflected as shown in the figure and the light output surface. It is output from the lower surface 23d (arrow A2). Therefore, the proportion of light energy attenuated inside the light guiding ring 23 is reduced, and the amount of light output from the lower surface 23d can be increased. FIG. 3C shows a second embodiment of the present invention, in which angles δ1,
A tapered surface of δ2 is provided, and FIG.
In this example, a tapered surface with an angle δ1 is provided on the outer surface 23b of the light guiding ring 23 in the portion where the light emitting element 22a is provided,
A tapered surface with an angle δ2 is provided on the outer side surface 23b at a position 180 sides apart, and the taper angle is gradually increased and decreased from one side to the other with δ1>δ2. In the configuration shown in FIG. 3C, since tapered surfaces are provided on both the inner and outer side surfaces 23b and 23c, the amount of light output from the lower surface 23d can be further increased compared to the configuration shown in FIG.

In addition, in the configuration shown in FIG. 3 2, the output characteristics near the taper angle δ2 are improved more than the output characteristics near the taper angle δ1, so as the distance from the light emitting element 22a increases, the level of the optical signal decreases. Even if this occurs, since the output characteristics in the vicinity are good, fluctuations in the level of the output from the lower surface 23d of the light guide ring 23 are reduced, and uniform light output can be obtained.

Therefore, it is possible to easily design and configure the amplifier circuit connected to the subsequent stage. Incidentally, in each of the above embodiments, the same effect can be obtained even if the tapered surface is made into a curved surface.
In addition, in the present invention, it is of course possible to use the light guiding ring formed as described above as a partial ring as necessary to cut off light transmission to the light receiving circuit at a predetermined rotation angle of the steering wheel. FIG. 4 shows a fourth embodiment of the present invention, which includes a steering wheel 13, a light guide ring 23 fixed to the steering wheel 13 and having a tapered surface 23b and a light output surface 23d, and a light guide ring 23, a light emitting element 22a embedded therein for inputting an optical signal, a light guide ring 40 for receiving light fixed to a steering post (not shown), and a light receiving element 24 embedded in the light guide ring 40 for receiving light. ing.

The light guide ring 40 for receiving light has an upper surface 40a which serves as an input surface for optical signals, and both inner and outer side surfaces 40b, 4 as shown in the figure.
0c and a lower surface 40d, and the outer surface 40b has a curved surface that coincides with an arc drawn around the center point P24 of the light receiving element 24 (if necessary, the inner surface 40c may also be provided with a curved surface. is also good). In the above configuration, the light emitting element 2
The optical signal output from 2a propagates inside the optical guide ring 23, is output from the optical output surface 23d, and is inputted from the upper surface 40 of the optical guide ring 40 for light reception.

The optical signal propagating through the light guiding ring 40 is received by the light receiving element 24, converted into an electrical signal, and input to a subsequent control circuit (not shown). In this case, since the light guide ring 40 has the curved surface 40b, for example, an optical signal input to point A is partially reflected at point B, and then reflected at point C of the curved surface 40b. The optical signal reflected at point C2 reaches the upper surface 40a again, but since the incident angle θ is configured to be larger than the critical angle of the material forming the light guide ring 40, it is totally reflected at point D, and the light guide ring It is possible to prevent the transmission loss from returning to within 40 and reducing the transmission loss. However, if the curved surface 40b is not formed but is formed on the vertical surface 40'b, the upper surface 40a
The optical signal that enters advances as A-+B-+C1→D1, and then
Since the rate at which the incident angle r at 1 becomes smaller than the critical angle increases, the light is radiated to the outside again, resulting in a reduction in transmission loss. Incidentally, the critical angle of the acrylic resin (mainly made from methyl methacrylate) that makes up the light guide ring is 42mm and 10', and the critical angle θ of other materials is, assuming that their refractive indexes are n, SinOx =
− can be determined by n.

Refractive index n of various materials that can constitute the light guiding ring
is as follows. As explained above, according to the optical signal transmission device according to the present invention, the outer and/or inner surfaces of the light guide ring are curved or tapered so as to increase the amount of light output from the light output surface, thereby reducing the load for vehicles. Transmission loss of the optical guide ring for optically transmitting control signals can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a vehicle load control device. FIG. 2A is a perspective view and a sectional view showing the optical signal transmission device in FIG. 1; FIGS. 3A, 3B, 3C are perspective views and sectional views showing the first to third embodiments of the present invention. FIG. 4A is a perspective view and a sectional view showing a fourth embodiment of the present invention. Explanation of symbols, 13...Steering wheel, 13a...Switch board, 17a-17
k... Steering switch, 21...
・Encoder circuit, 22...Electronic conversion circuit, 2
2a...Light emitting element, 23...Light guide ring, 23a, 23b, 23c, 23d...Top surface, outer surface, inner surface, bottom surface of light guide ring, 24...・・・
・Photodetector, 25...Amplification circuit, 26...
... Threshold circuit, 27 ... Encoder circuit, 28
... Drive circuit, 30 ... Steering post, 40 ... Light guide ring for light reception.

Claims (1)

[Scope of Claims] 1. A light emitting circuit that outputs an optical signal according to a signal output by each operation of a plurality of steering switches provided on a steering wheel, an optical signal output surface, and light propagating inside. a guide ring having a tapered or curved guide surface for guiding a signal to the optical signal output surface, and for inputting the optical signal output from the light emitting circuit and outputting it from the optical signal output surface; An optical signal transmission device comprising: a light receiving circuit that receives the optical signal output from the ring and outputs a signal corresponding to the optical signal for controlling a vehicle load. 2. The optical signal transmission device according to claim 1, wherein the leading ring has a donut shape, and the guide surface is provided on an outer surface and/or an inner surface thereof. 3. The guiding surface of the leading ring has a configuration in which a taper angle or degree of curvature gradually increases from a portion of the light emitting circuit where the optical signal is input to a position axially symmetrical to the portion. Optical signal transmission equipment. 4. The light-receiving circuit receives the light-receiving leading ring that inputs and propagates the optical signal output from the leading ring, and the light-receiving leading ring that receives the optical signal that propagates within the light-receiving leading ring and outputs a signal according to the optical signal. 2. An optical signal transmission device according to claim 1, comprising a light receiving element.