JPH0373920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention multiplexes input signals from a plurality of switches provided on a steering wheel in a vehicle, converts the signals into optical signals, and then transmits them to a fixed part in the vehicle. The present invention relates to a multiplex signal transmission device for a vehicle, which receives multiplexed signals by a light receiving element provided on a fixed part thereof and further demultiplexes the multiplexed signals from the light receiving element.

<Prior art> As shown in FIGS. 1 and 2, a conventional multiplex signal transmission device of this type has a steering handle 11 provided with a plurality of switches 12 for various indicator lights, air conditioning, radio settings, etc. The signals input by the plurality of switches 12 are multiplexed by the encoder 13, and the multiplexed signal passes through the drive circuit 14 and causes the light emitting element 15 to emit light. The light emitting element 15 is provided within a light guide ring 16 made of acrylic resin, for example, and light from the light emitting element 15 propagates within the light guide ring 16. As shown in FIG. 2, a light receiving element 17 is provided on a fixed part, that is, on the vehicle body side, close to and facing the outer peripheral surface of the light guide ring 16, and the light from the light guide ring 16 received by the light receiving element 17 is transmitted through a transmission path 18. The amplified output is supplied to the amplification element 19, whose amplified output is waveform-shaped by a waveform shaping circuit 21, and further demultiplexed by a decoder 22, and one or more of the loads 23 corresponding to each of the switches 12 are controlled.

The light guide ring 16 is rotated simultaneously by the operation of the steering handle 11, and has a diameter of, for example, 60 mm.
It has a size of about a millimeter. Therefore, if the light emitting element 15 is located near the light receiving element 17, a sufficiently strong optical signal can be received from the light guide ring 16, but the distance between the light emitting element 15 and the light receiving element 17 is approximately 180 degrees with respect to the axis of the light guide ring 16. If they are far apart, the level of the optical signal received by the light receiving element 17 will drop considerably. In other words, in this conventional device, it was difficult to output a uniform optical signal over the entire circumferential surface of the light guide ring 16.

It is conceivable to make cuts or the like inside the light guide ring 16 in order to make the output of the optical signal almost uniform on each part of the circumferential surface of the light guide ring 16, but the light guide ring 16 would have a complicated shape, and the light guide ring 16 would have a complicated shape. The light level in each part of the amplifier 19 becomes relatively weak, and it is necessary to increase the sensitivity of the amplifier 19 in order to detect optical signals. Increasing the sensitivity is not preferable because it tends to become unstable. Additionally, there was a risk that external noise would be induced into the cable 18 between the light receiving element 17 and the amplifier 19.

<Summary of the Invention> An object of the present invention is to provide a vehicle multiplex signal transmission device that has a relatively simple structure and can stably obtain a substantially uniform optical signal regardless of the rotational angle position of the steering wheel. .

According to this invention, signals inputted by a plurality of switches provided on a steering wheel are multiplexed, and a plurality of light emitting elements are simultaneously driven by the multiplexed signals. The plurality of light emitting elements are arranged at approximately equal angular intervals on the circumference around the steering shaft, and the chips of each light emitting element are directly attached to the wiring board, and the wiring board is connected to the steering shaft (shaft). It is attached to the rotating part that rotates together with the The reflecting surface gradually opens around each light emitting element as it moves away from the wiring board, and the light from each light emitting element is directed by the reflecting surface to form a uniform ring-shaped light as a whole. A light ring-forming housing is provided that forms an illumination surface. This optical ring forming housing is provided on the wiring board side. On the other hand, a light receiving element is provided on a fixed part on the vehicle body side in close opposition to the ring-shaped light irradiation surface. The light is received by this light-receiving element and converted into an electric signal, which is further demultiplexed by a demultiplexing circuit, and its output drives each load.

<Embodiment> Electrical system FIG. 3 shows an electrical system in a multiplexed signal device according to the present invention, in which a plurality of operation switches 12 provided on the steering wheel of a vehicle are used for, for example, a radio receiver, air conditioning equipment, etc. These are for various indicator lights, etc., and the signals inputted by these switches 12 are multiplexed by a multiplexing circuit 24. This multiplexing circuit 24
is composed of, for example, a microprocessor or a gate array, and this multiplexed signal output drives a plurality of light emitting elements _D1 to _D0 through a drive circuit 25. These light emitting elements _D1 to Dn are connected in parallel, one end of which is connected to the output side of the drive circuit 25, and the other end connected to the power supply terminal 2.
Connected to 6.

Optical signals emitted from these light emitting elements D _{1 .} . . D _o are received by the light receiving element 27. The light receiving element 27 is provided on a fixed part on the vehicle body side, and the electrical signal converted by the light receiving element 27 is amplified by an amplifier 28, and further converted into an optical signal by an optical conversion circuit 29 in this example. The signal is received by the optical receiving circuit 31 on the load side via an optical fiber or a photocoupler. This optical signal is converted into an electrical signal by the optical receiving circuit 31, and the electrical signal is separated into electrical signals corresponding to each switch 12 by the demultiplexing circuit 32, and the corresponding load 33 is driven.

Structure The electronic circuit section 34 including the multiplexing circuit 24 and the drive circuit 25 shown in FIG.
Each operation switch 12 is attached to the top. A light emitting ring 37 is arranged around the steering shaft 35, _and as shown in _FIG . A light emitting ring assembly 41 is provided which includes a contact 38 and a power supply slip ring contact 39 for the electronic circuit section 34.

A light receiving module section 42 including a light receiving element 27 such as a photodiode or a phototransistor and an amplifier 28 is located at a position facing the light emitting ring 37 on the steering post side, which is a fixed part on the vehicle body side.
(Fig. 3) and a conversion section 4 consisting of an optical conversion circuit 29
3 is provided facing the light emitting ring assembly 41. The conversion portion 43 is provided coaxially with the shaft 35, but is fixed to the vehicle body without contacting the shaft 35. Furthermore, as shown in FIG. 6, a slip ring 44 is provided on this converting portion 43 to make sliding contact with the horn slip ring contact 38, and a slip ring 45 for an electronic circuit is provided coaxially with this slip ring 44. provided. That is, these slip rings 44 and 45 are the slip ring contacts 3.
8 and 39, respectively. This converter 4
3 is connected to an optical connector for optical fiber transmission or a connector 46 containing a photocoupler drive signal.

Light-emitting ring The light-emitting ring 37 is composed of a plate ring-shaped wiring board 47 and a light ring forming housing 48, as shown in FIGS. 7 to 10. The wiring board 47 has light emitting elements D ₁ to D1 arranged at equal angular intervals around its center.
The light-emitting elements _{D 1 to} D ₈ do not require packages such as cases or molded resin, and the semiconductors, so-called chips, having a PN junction that constitute the light-emitting elements themselves are connected to the electrodes and the wiring board 47.
installed in direct contact with the wiring above the

A ring-shaped housing 48 is in contact with the wiring board 47 at one end surface, and the other end surface is a ring-shaped opening 49. In this example, the ring-shaped opening 49 is closed with a plate-ring-shaped light guide plate 51. It's broken. The outer surface of this light guide plate 51 is a ring-shaped light irradiation surface 5.
2.

The light ring forming housing 48 is formed so that the light from the light emitting elements D ₁ to D _o is directed by the light ring forming housing 48 to form one substantially uniform ring-shaped light irradiation surface 52. ing.
That is, as shown in FIG. 8, the optical ring forming housing 48 is viewed in a cross section perpendicular to the direction along the ring, that is, the opposite inner circumferential surface 4 of the housing 48.
9a and 49b are light emitting elements D _i (i=1, 2,...8)
The slopes gradually open to each other as they approach the irradiation surface 52 from the side. These opposing inner circumferential surfaces may be curved surfaces that are convex outward from each other as shown in FIG. 9. In other words, in the cross section of FIG. 9, the light emitting element D _i may be located.

Further, as shown in FIG. 10, the surface of the light ring forming housing 48 on the wiring board 47 side gradually approaches the ring-shaped light irradiation surface 52 between adjacent light emitting elements D _i , as shown in the cross section along the ring. Sloping slopes 49c and 49d are formed. In other words, the first
In the cross section shown in Figure 0, the light emitting element D _i is arranged deep in the short axis direction of the semi-elliptical inner surface. In other words, each light emitting element D _i is located deep inside the semi-spheroidal inner surface. In this way, the opposing inner circumferential surfaces 49a, 49b, slopes 49c, 4
9d directs the light from each light emitting element D _i to form a ring-shaped irradiation surface 52. These opposing inner circumferential surfaces 49a, 49b and slope 49 as necessary.
The surfaces c and 49d are subjected to surface treatment such as white paint or aluminum vapor deposition, so that the light from the light emitting element D _i is effectively reflected.

In this example, eight light emitting elements D _i are provided.
Although they are installed at 45° intervals, the number of light emitting elements can be increased or decreased depending on the required size of the light emitting ring 37 and the required strength of the optical signal.
The light ring forming housing 48 is made, for example, as a molded product of synthetic resin material, and claws 53 are integrally protruded from the wiring board 47 side at appropriate positions on the outer peripheral edge and inner peripheral edge of the housing. The claws 53 are made to protrude to the opposite side of the wiring board 47 through recesses 54 provided on the outer peripheral surface and the inner peripheral surface.
7 to fix the wiring board 47 and the optical ring forming housing 48 to each other.

Light receiving part Light emitting ring 3 as shown in Fig. 4 and Fig. 10
A light receiving element 27 is provided closely facing the ring-shaped light irradiation surface 52 of No. 7. The light-receiving element 27 is located at the most retracted portion of the light-converging inner surface that focuses the light from the ring-shaped light irradiation surface 52, for example, the semi-spheroidal inner surface 55. The length d ₁ of the opening of the light focusing inner surface 55 in the direction along the ring of the light emitting ring 37 is set to be the same as or slightly larger than the interval d ₂ between adjacent light emitting elements D _i . Further, if necessary, a focusing lens 56 can be attached to the opening of the light focusing inner surface 55 as shown in FIG. It is preferable that this light converging inner surface 55 is also subjected to surface treatment using white paint or aluminum vapor deposition. As mentioned above, the light receiving module 42 includes the light receiving element 27, the amplifier 28 for amplifying its output, and the optical conversion module 29 as needed, that is, it is configured as a single semiconductor chip. If necessary, this outer peripheral surface can be shielded from noise with aluminum.

<Other Examples> As shown in FIG. 12, a light emitting ring 37 is provided coaxially around the outer periphery of the shaft 35, and a ring-shaped light irradiation surface 52 is formed on the circumferential surface instead of the end surface. The conversion portion 43 may be provided on the outer periphery of the surface 52, facing the surface 52. In this case, a flexible substrate is used as the wiring board 47 of the light emitting ring 37. The wiring board 47 has a ring-shaped mounting portion 5
7 is fixed to the shaft 35.

<Effects> As described above, the multiplex signal transmission device for a vehicle according to this invention uses a plurality of light emitting elements D _i , which form a substantially uniform ring-shaped light irradiation surface 52; Since the light receiving element is provided on the light irradiation surface 52, a substantially uniform optical signal can be received regardless of the rotation angle position of the steering wheel. In order to form the ring-shaped light irradiation surface 52, the opposing inner circumferential surfaces 49a, 49b and slopes 49c, 49d can be easily formed into a desired shape using, for example, a resin molded product. Moreover, by performing surface treatment on these surfaces, it is possible to obtain strong optical signals. As in the previous example, when transmission to the load side is performed by converting it into an optical signal, a feature that is not affected by noise can be obtained. Furthermore, by forming the light condensing inner surface 55 on the light receiving element side as in the previous example, it is possible to receive a sufficiently strong optical signal even when the light receiving element 27 is located between adjacent light emitting elements.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional vehicle multiplex signal transmission device, FIG. 2 is a diagram showing the relationship between the light guide ring and the light receiving element, and FIG. 3 is an electrical diagram of an example of the vehicle multiplex signal transmission device according to the present invention. A block diagram showing the system, FIG. 4 is a sectional view showing the structure of the vehicle multiplex signal transmission device according to the present invention, and FIG.
6 is a sectional view taken along line BB in FIG. 4, FIG. 7 is an exploded perspective view of the light emitting ring 37, and FIG.
The figure is a sectional view perpendicular to the light emitting ring, FIG. 9 is a sectional view showing another example, FIG. 10 is a sectional view along the ring of the light emitting ring and the light receiving module, and the first
FIG. 1 is a sectional view showing another example of the light receiving section, and FIG. 12 is a sectional view showing the structure of another example of the vehicle multiplex signal transmission device according to the present invention. 12: switch, 24: multiplexing circuit, 25: drive circuit, 27: light receiving element, 32: multiplexing/demultiplexing circuit,
37: light emitting ring, 47: wiring board, 48: light ring forming housing, 52: ring-shaped light irradiation surface,
49a to 49d: inner surface for directing light, 55: curved surface for focusing, D ₁ to D _o : light emitting element.

Claims (1)

[Claims] 1. A multiplexing circuit that multiplexes signals corresponding to inputs from a plurality of switches mounted on the steering wheel and generates the multiplexed signal, a plurality of light emitting elements simultaneously driven by the multiplexed signal, and the steering wheel. a wiring board provided on a rotating part that rotates together with the steering shaft, on which chips of the plurality of light emitting elements are mounted at approximately equal angular intervals on a circumference around the shaft;
A reflecting surface is provided on the wiring board and gradually opens around each of the light emitting elements as it moves away from the wiring board, and the light from each light emitting element is directed by the reflecting surface to reflect the light as a whole. A housing for forming a light ring forming a substantially uniform ring-shaped light irradiation surface, a light receiving element provided on a fixed part on the vehicle body side in close opposition to the ring-shaped light irradiation surface, and light received by the light receiving element. and a demultiplexing circuit that amplifies and shapes the multiplexed signal and demultiplexes the multiplexed signal.