Optical waveguides – With optical coupler – Movable coupler
Reexamination Certificate
2000-05-30
2002-03-05
Spyrou, Cassandra (Department: 2872)
Optical waveguides
With optical coupler
Movable coupler
C359S199200, C359S199200, C359S199200, C385S042000, C385S025000
Reexamination Certificate
active
06353693
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an optical communication device for bidirectionally sending control signals between a rotor-side circuit on the side of a rotary table and a stator-side circuit outside of the rotary table, including the circuit of a host computer, as well as a slip ring unit for an electronic component-mounting apparatus, for electrically and continuously connecting between a rotor-side circuit on the side of a rotary table and a stator-side circuit outside of the rotary table.
2. Prior Art
Conventionally, an optical communication device of this kind has been proposed e.g. by Japanese Laid-Open Patent Publication (Kokai) No. 8-83998, which is installed in a high-speed mounter. In the high-speed mounter, rotary table-side motor drivers on a rotor side and a host computer-side circuit on a stator side are connected to each other by an optical coupler formed by a pair of light-emitting/receiving elements, via which input/output (optical communication) of control signals is performed between the host computer and the motor drivers.
In the optical coupler, one of the light-emitting/receiving elements is secured on an end face of a shaft of the rotary table, and the other on an end face of a base, the two elements being opposed to each other on the rotation axis of the shaft.
As described above, in the conventional optical communication device, since the pair of light-emitting/receiving elements each serving as both a light-emitting element and alight-receiving element are used, each light-receiving element (light-receiving portion) is not capable of receiving light from an opposed light-emitting element (light-emitting portion) completely separately from light from an adjacent light-emitting element (light-emitting portion). To overcome this problem, the conventional optical device needs provision of a modulation circuit and a demodulation circuit, which results in an increase in manufacturing costs of the device.
In a high-speed mounter disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 6-37488, a plurality of slit disks and a plurality of photo-interrupters opposed to the slit disks are arranged on top of the shaft of a rotary table, to form detection means for sensing the positions of a plurality of mounting heads carried by the rotary table.
On the periphery of the rotary table, there are arranged mounting heads corresponding in number to the number of indexing steps for one turn of the rotary table, and further, around the periphery of the rotary table there are arranged a plurality of work stations including one for picking up an electronic component by vacuum and one for mounting the picked electronic component, in number dependent on the number of the indexing steps for one-turn of the rotary table, where face the mounting heads in temporary stoppage.
The above detection means detects which of the mounting heads that are assigned respective head numbers is positioned at which of the work stations, thereby enabling control of rotation and upward and downward motion of each of the mounting heads.
The mounting heads each carry a motor for rotating and lifting up and down itself, and supply of electrical drive power and input (or input/output) of a control signal are carried out via a slip ring mounted on the shaft of the rotary table. Therefore, in the conventional high-speed mounter, the slip and the above sensing means are arranged on the shaft of the rotary table separately from each other, and this not only requires a large installation space, but also increases the number of components and the steps of assembly process.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide an optical communication device for permitting appropriate bidirectional optical communication between a stator-side circuit and a rotor-side circuit by ensuring separation of lights transmitted in opposite directions.
It is a second object of the invention to provide a slip ring unit which can attain the reduction of the number of components and space for installation of the components by unitizing a slip ring and rotation-sensing means of a rotary table.
To attain the first object, according to a first aspect of the invention, there is provided an optical communication device for communicating between a circuit arranged on a side of a stator and a circuit arranged on a side of a rotor having an axis of rotation.
The optical communication device according to the first aspect of the invention is characterized by comprising:
a pair of optical couplers arranged between the stator and the rotor, for permitting signals to be bidirectionally transmitted between the circuit arranged on the side of the stator and the circuit arranged on the side of the rotor,
one of the pair of optical couplers having a rotor-side light-receiving element arranged on the rotor such that the axis of rotation extends therethrough, and a stator-side light-emitting element arranged on the stator at a location away from the axis of rotation and having an optical axis directed toward the rotor-side light-receiving element, and
another of the pair of optical couplers having a stator-side light-receiving element arranged on the stator such that the axis of rotation extends therethrough, and a rotor-side light-emitting element arranged on the rotor at a location away from the axis of rotation and having an optical axis directed toward the stator- side light-receiving element.
According to this optical communication device, in one of the optical couplers, an optical signal emitted from the stator-side light-emitting element is received by the rotor-side light-receiving element, while in the other of the optical couplers, an optical signal emitted from the rotor-side light-emitting element is received by the stator-side light-receiving element.
The optical axis of the stator-side light-emitting element is directed toward the rotor-side light-receiving element on the axis of the rotor, and hence, even when the rotor-side light-receiving element rotates with rotation of the rotor, the optical signal from the stator-side light-emitting element does not miss the rotor-side light-emitting element and is positively received thereby. Similarly, the optical axis of the rotor-side light-emitting element is directed toward the stator-side light-receiving element on the axis of the rotor, and hence, even when the rotor-side light-emitting element rotates with rotation of the rotor, the optical signal from the rotor-side light-emitting element does not miss the stator-side light-receiving element and is positively received thereby.
Further, since the rotor-side light-emitting element is arranged at a location away from the axis of rotor, the rotor-side light-emitting element and the rotor-side light receiving element on the axis of the rotor do not interfere with each other by their locations. Similarly, since the stator-side light-emitting element is arranged at a location away from the axis of rotor, the stator-side light-emitting element and the stator-side light receiving element on the axis of the rotor do not interfere with each other by their locations.
Preferably, the stator-side light-emitting element and the stator-side light-receiving element are mounted on the stator in a state molded into one piece by using an optically transparent resin, and the rotor-side light-emitting element and the rotor-side light-receiving element are mounted on the rotor in a state molded into one piece by using an optically transparent resin.
Preferably, the stator-side light-emitting element and the rotor-side light-emitting element are each formed by a device selected from the group consisting of a light-emitting diode and a laser diode.
Preferably, the stator-side light-receiving element and the rotor-side light-receiving element are each formed by a device selected from the group consisting of a photo-transistor and a photo-diode.
To attain the first object, according to a second aspect of the invention, there is provided an optical communication device for comm
Kano Yoshinori
Nagata Takahiro
Takemura Ikuo
Darby & Darby
Maxie Christopher S.
Sanyo Electric Co,. Ltd.
Spyrou Cassandra
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