JPH0623011U - Optical rotary connector - Google Patents

Abstract

(57) [Abstract] [Purpose] Transmitting multiple digital signals to a rotating body by data transmission using light in the radial direction. In a signal transmission means for transmitting a signal to a rotating body, an OE conversion means for receiving light in a radial direction on a rotating shaft and an EO conversion for projecting light on a fixed portion surrounding the shaft toward the OE means. Configuration with means attached. In addition, multiple configurations of this configuration are arranged along the longitudinal direction of the axis to enable transmission of multiple signals.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to means for transmitting signals to rotating parts.

[0002]

[Prior art]

 Conventionally, slip rings have been used to transmit data to rotating parts. However, the slip ring had a problem of wear. In addition, since the brushes are in mechanical contact with each other, electrical noise may occur, which is not suitable for high-speed signal transmission.

On the other hand, there was a connector for connecting an optical fiber to the rotating part. That is, the connector axis can be rotated by aligning the rotation axis with the center axis of the optical fiber. Optical fibers can transmit data at high speed. However, there was a problem in that it could only be attached to the shaft end due to the configuration, and the number of signal channels could be only one. Therefore, when sending multiple signals, they must be multiplexed by a multiplexer and separated by a decoder. Then, since the signals are multiplexed and multiplexed, the EO and OE conversions tend to be expensive.

[0004]

[Problems to be solved by the device]

 The problem we are trying to solve is that it can be attached to a rotating object in the middle of the rotation axis, and there is no means to send high-speed digital signals of multiple channels.

[0005]

[Means for Solving the Problems]

 In the present invention, the OE conversion element is attached to the rotary shaft, and the EO conversion means for projecting light from the radial direction to the OE conversion element is provided on the fixed side. It has become possible to transmit signals with. In addition, this allows multiple transmission means of the same configuration to be arranged in the longitudinal direction of the shaft, enabling transmission of multiple signals.

[0006]

【Example】

 Although the present invention is a means for transmitting a signal to a rotating body, application to a rotating display device will be described as a first embodiment. This display device is the display device of Japanese Patent Application No. Hei 1-358 44 by the same inventor.

FIG. 1 shows a schematic mechanism of a display device. The rotating portion 4 is rotated by the motor 2 via the belt 3. The LED array 5 is attached to the outside of the rotating part, and the display is performed according to the rotation, and the afterimage is displayed on the circumference. In addition, this display device has the feature that the display is transparent because the LED array draws an image in the air with an afterimage. In order to make full use of this feature, a fixed table 6 that does not rotate is provided in the rotating part. If you fix the exhibit on this, you can see the display and the display at the same time. The mercury rotary connector 7 supplies power to the rotary unit. An optical rotary connector 8 for transmitting a signal to the rotating portion is located below that.

FIG. 2 is a circuit block diagram of this display device. The fixed side has an image memory, a control unit, a position sensor, and a power supply (not shown). There are four LED display substrates on the rotation side. DATA, SCK and LCK signals are output from the control section. These three signals are transmitted to the rotating unit via the optical rotary connector. The DATA signal is serial data of a pattern for turning on the LED. SCK is a synchronous clock for serially transferring the DATA signal. That is, the display data SCK is serially transferred in synchronization with the clock. LCK is a signal for latching the transferred column display data in the LED display circuit. The transferred data becomes a lighting pattern only after being latched. Power is supplied to the rotating part by a mercury rotary connector (not shown). Since the present invention is a signal transmission means, description of the circuit operation is omitted.

The required data amount is about 5.2 Mbit / sec when the number of vertical dots is 128, the number of vertical lines per revolution is 512, the number of rotations is 10 times / sec, two-color emission, and the number of substrates is 4. Therefore, the serial transfer rate will be higher than this.

FIG. 3 shows an enlarged view of the optical rotary connector and the mercury rotary connector. The optical rotary connector is for transmitting three signals in this example. The light-transmitting part substrate 11 is stacked on the right side, and the light-receiving part substrate 13 is mounted on the rotating shaft 12. The LED 14 mounted on the light projecting portion substrate emits light in response to a signal, and the light receiving element 15 arranged around the rotation axis captures this and returns it to an electric signal. The light projecting portion substrate 11 is located on one side of the shaft and is stacked by the spacer 16.

The light-receiving substrate 13 is a donut-shaped substrate, and is fixed to the rotating shaft 12 by a ring-shaped spacer 17 at regular intervals. The light-receiving substrate 13 also functions as a separator that prevents the light of the LED 14 from leaking to the vertically adjacent steps.

FIG. 4 is an external view of a substrate for one channel of the optical rotary connector. Projection unit Six LEDs 14 are mounted on the substrate 11 at intervals of 20 degrees toward the center of the rotation axis. The LED 14 is a high-brightness red LED whose directivity is narrowed. Further, a driver IC 18, a current limiting resistor 19, a capacitor 20 and a connector 21 are mounted on this board. In this way, since the LED is positioned by the holes in the substrate after bending the leads with a jig, the number of parts is small and it is simple.

On the other hand, three light-receiving elements 15 are attached around the rotary shaft 12 at intervals of 120 degrees. The diameter of the rotating shaft 12 is 20 mm. The distance between the LED and the light receiving element is 2 mm. In this way, when the shaft diameter is 20 mm, it is composed of three light-receiving elements and six LEDs, but when the diameter is different, the guideline for the required number is determined by the procedure shown below.

[0014]

[Equation 1] Number of divisions in one round = (shaft diameter +4) x π / (width covered by LED) (1)

## EQU00002 ## The number of light receiving elements.times.the number of LEDs> = the number of divisions in one round ... (2)

## EQU00003 ## In the embodiment, the width covered by the LED is determined to be about 4.5 mm. Therefore

## EQU00004 ## The number of divisions in one cycle = 24.times..pi. / 4.5 = 16.7

In this case, considering that the light receiving element is more expensive than the LED and that three LEDs can be driven by one driver, it is appropriate to divide one circumference into 18 by three light receiving elements and six LEDs. Becomes Since the angle at which the light receiving element divides the circumference is 120 degrees, the LEDs are arranged at intervals of 20 degrees, which is 6 minutes.

Here, it is also possible to arrange LEDs around the periphery at an interval of 60 degrees of 360 degrees / 6 and arrange the light receiving elements at intervals of 20 degrees within 60 degrees. However, the LED board becomes large and it is not practical. Also, if the LED board is not divided into two, it will be difficult to attach and detach. Furthermore, the rotation axis becomes unbalanced. Therefore, it can be said that it is rational to install the light-receiving elements around the axis at equal intervals and concentrate the LEDs within the angle formed by the light-receiving elements.

FIG. 5 shows a circuit configuration. The LED is driven by a driver 18 having a symmetrical impedance in order to quickly release the charge due to the internal junction capacitance and accelerate the turn-off of light emission. Similarly, a capacitor 20 is connected in parallel with the current limiting resistor 19 in order to quickly release the charge and to superimpose the differential component on the LED current.

The capacitance of the capacitor has the following calculated value only for the purpose of releasing the junction capacitance charge of the LED. As a premise, the junction capacitance of the LED is 200 pF, Vf = 1.8 V, If = 30 mA, the output impedance is about 16Ω, and the drive voltage = 5 V.

[0019]

## EQU00005 ## C = 200 pF.times.1.8 / (5-1.8-16.OMEGA..times.30 mA) = 132 pF

A larger capacitance is added for superimposing the differential component, but due to the limitation of the peak current of the LED and the capacitive load that can be driven by the driver, 1200 pF or so is suitable in this example.

In the embodiment, two elements are used in parallel due to the limitation of the power dissipation of the driver package. For this reason, the output impedance can be further reduced, contributing to speeding up.

The light receiving element is a plastic optical fiber data link optical IC (one in which processing circuits such as a photodiode and an amplifier are integrated into one chip) TPS823. The circuit configuration is that of FIG. Since the output part is an open collector, the OR output of each light receiving element can be obtained by simply making a wired OR and attaching the pull-up resistor 22. The output of this IC transits digitally, but strictly speaking, it takes an intermediate value when the light quantity is slightly insufficient. That is, there is a linear area. In this area, the wired OR output is the addition of the outputs of multiple elements. Therefore, even if it seems that the irradiation light of the LED that corresponds to one light receiving element is insufficient because it is the peripheral part of the LED array as shown in FIG. 4, the amount of light received in the LED array and the output of the investment price are can get.

A digital signal of DC-10 MHz can be transmitted by the above combination of light projection / light reception. In addition, the tolerance for mounting position accuracy is about ± 2 mm in the axial direction and ± 1 mm in the radial direction at 10 MHz, but the lower the frequency, the greater the allowable range.

When higher-speed transmission is required, it is possible to construct a light-receiving circuit by using a photodiode and a high-speed amplifier instead of the existing opto-IC. In that case, it is necessary to select an LED with a small junction capacitance. The light projecting circuit is also preferably of the current mirror type used in optical communication.

FIG. 6 shows a light receiving unit according to another embodiment. A light receiving element is attached to the flexible substrate 23 with its light receiving surface parallel to the substrate. The leads of the light receiving element are appropriately formed so that they can be surface-mounted. The board has double-sided wiring, and the wiring on the front and back is not particularly distinguished in the figure, but the intersections that have no intersection intersect the front and back. The three light receiving elements in a row correspond to the light receiving section of one channel, and the output Vo (2pin) of each element is combined and connected to the right signal lead-out section.

The substrate is not limited to the four stages shown in the figure, but there are, for example, 12 to 24 stages, and an arbitrary number of stages can be cut and used. However, if signals are taken out on the board, up to four stages can be handled in this example. If the points marked with X in the figure are removed by punching, the wiring of the right signal extraction part can be assigned to the output signal of each stage. Also, the number of elements in one stage may be three or more, and it is advisable to mount and cut as many elements as necessary according to the shaft diameter. In this case, combine the power supply and signal line on one side.

A method of mounting this board will be described. The simplest method is to wrap the substrate with the element outside and wrap it around a shaft, and fix it with double-sided tape. Further, as shown in FIG. 7, a dedicated pipe 24 having a recess for accommodating the light receiving element is attached to the axis, a flexible substrate is wound around this, and a transparent pipe 25 is covered. In this case, the light receiving element requires a substrate that is mounted with the light receiving surface facing the substrate side. Open a window in the part of the substrate that corresponds to the light receiving part of the light receiving element. The substrate is wound on the pipe with the element inside. Fasten it with double-sided tape and cover it with a transparent pipe on the outside. By adhering in this state, the shaft can be removed and modularized as a pipe-shaped part.

FIG. 8 shows a light projecting unit according to another embodiment. The LED is attached to the substrate parallel to the rotation axis by a resin holder 26 in a centripetal manner. As shown in Fig. 9, the holder has a groove that can receive the LED lead. Make one half and attach it to the left and right. Positioning / fixing of the holder to the board is done by the boss. In this case, the light projecting portions for a plurality of channels can be attached to one substrate by arranging them in the direction perpendicular to the paper surface. In addition, it can be formed on a part of the other circuit board so as to be an integrated board.

FIG. 10 shows a light projecting unit and a light receiving unit according to another embodiment. The light emitted from the LED 14 can be emitted from the surroundings of the rotating shaft 12 from 180 degrees or more by the light projecting and guiding component 27 made of transparent resin. The light receiving element is also embedded in the light receiving and guiding component 28 to improve the directivity. Therefore, the number of LEDs and light receiving elements can be reduced. In addition, the light-conducting light-guiding component and the light-receiving and light-guiding component face each other in the shape of a semi-cylindrical lens, so that light is collected as much as possible on a small light receiving surface.

When the amount of light is insufficient, an LED with high brightness may be used. For example, an ultra-bright LED of 3000 m cd or more is used. Also, use a light receiving element with a large light receiving surface. The reflective surface of the light guide component may be plated with aluminum by vapor deposition. If the diffusion of light is not uniform, a diffusing material may be mixed into the resin to make it uniform.

The shape of the light guide component / the number of elements is not limited to this example. In this example, the light emitting part can be attached or removed from one side of the shaft.

As described in the embodiments, the optical rotary connector of the present invention is used to send a digital signal to the rotating body, but it is also used to extract the signal from the rotating portion so that it can be easily analogized. It can be applied.

[0033]

[Effect of device]

 As described above, the optical rotary connector of the present invention can transmit multi-channel high-speed digital signals of about 10 MHz to the rotating part. Further, as described in detail in the embodiment, the cost can be reduced.

Further, taking the display device of the embodiment as an example, the display data and the control circuit, which were conventionally in the rotating part, can be brought to the fixed side, and therefore, there are the following advantages.・ Display data can be easily exchanged.・ Especially, even if the rotating display part is high like an advertising tower, if the signal line is extended to the bottom and the control board and ROM card are attached below, the display data can be exchanged under the pillar. . -By moving the control board to the fixed side, it is possible to display multiple display units in synchronization with each other using a synchronization signal. In addition, data can be distributed to a plurality of display devices from one centralized data generation / control means. -A connector can be installed on the pedestal to load data with signals from the modem.・ Even when controlling the rotation of the motor, the circuit can be configured on the same substrate as the display control unit, which is economical.

[Brief description of drawings]

FIG. 1 is a schematic view of a mechanism of a display device according to a first embodiment.

FIG. 2 is a circuit block diagram of a first embodiment.

FIG. 3 is an enlarged view of an optical rotary connector portion of the first embodiment.

FIG. 4 is an external view of the substrate of the first embodiment.

FIG. 5 is a circuit configuration diagram of the present invention.

FIG. 6 is a schematic view of a flexible substrate used in a second embodiment.

FIG. 7 is an explanatory view of mounting in the second embodiment.

FIG. 8 is an explanatory view of mounting in the third embodiment.

FIG. 9 is an enlarged view of parts used in the third embodiment.

FIG. 10 is an external view explanatory diagram in the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary display device 2 motor 3 belt 4 rotating part 5 LED array 6 fixed table 7 mercury rotary connector 8 optical rotary connector 9 control board 10 memory card 11 light emitting board 12 rotary shaft 13 light receiving board 14 LED 15 light receiving element 16 Spacer 17 Ring-shaped spacer 18 Driver IC 19 Current limiting resistor 20 Capacitor 21 Connector 22 Pull-up resistor 23 Flexible substrate 24 Recessed pipe 25 Transparent pipe 26 Holding device 27 Projecting light guiding component 28 Light receiving and guiding component

Claims (11)

[Scope of utility model registration request] 1. A transmission means for transmitting an electric signal between two members that rotate with each other, at least one EO conversion element for converting the transmitted signal into light, and at least returning the light to an electric signal. A rotary connector having one O-E conversion element. 2. The irradiation direction of the light output from the EO conversion element is perpendicular to the rotation axis (radial direction), and
A plurality of O-E converting means are arranged in a longitudinal direction of a shaft on a rotating shaft, and a plurality of EO converting means corresponding thereto are provided so that a plurality of signals can be transmitted. 1
The described rotary connector. 3. A plurality of OE conversion means are arranged radially in a rotationally symmetrical manner about an axis, and a plurality of EO conversion means are arranged around the OE conversion in a radial direction within a whole circumference or within a certain angle. The rotary connector according to claim 1, wherein the rotary connectors are arranged side by side. 4. The EO conversion means is characterized in that a plurality of light receiving elements are radially arranged at an equal angle within an angle dividing a circumference, with the light emitting direction directed toward the rotation center. The optical rotary connector according to claim 3. 5. The optical rotary connector according to claim 5, wherein the O-E conversion means comprises at least a donut-shaped substrate perpendicular to the rotation axis and a plurality of light receiving elements. 6. The optical rotary connector according to claim 4, wherein the OE converting means comprises at least a flexible substrate wound around an axis and fixed, and a plurality of light receiving elements mounted on the flexible substrate. 7. The optical rotary connector according to claim 5, wherein the EO conversion means comprises a substrate parallel to the rotation axis, an LED, and a holder for mounting the LED in an arc shape. 8. The rotary connector according to claim 1, wherein the EO conversion means comprises an LED, a symmetrical output impedance driver, and a current limiting resistor. 9. The rotary connector according to claim 8, wherein a capacitor is attached in parallel with the current limiting resistor in order to improve the responsiveness of EO conversion. 10. The optical rotary according to claim 2, wherein the light receiving element of the O-E means has a transparent or light guiding means containing a diffusing material to expand the directivity and reduce the number of light receiving elements. connector. 11. The EO conversion means has a light guide means for reflecting and diffusing light emitted from the light emitting element and irradiating the light from the periphery of the rotation axis, or a light guide means containing a diffusing material. The optical rotary connector according to claim 2, wherein the number of driving means is reduced.