Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-10-30
2004-04-06
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S540000, C340S539230, C340S505000, C340S870030, C340S008100, C359S199200
Reexamination Certificate
active
06717515
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a sensor system including a large number of sensor units (such as optical fiber photoelectric sensor units, proximate sensors or ultrasonic sensors) mounted closely one next to another typically on a DIN rail, and in particular to a sensor system which simplifies the setting operation and monitoring of settings of such sensor units by enabling a bi-directional data communication between the adjacent sensor units in the manner of a bucket brigade.
BACKGROUND OF THE INVENTION
Sensor systems including a large number of optical fiber photoelectric sensor units mounted closely one next to another on a DIN rail are conventionally known. The outer face of each of such sensor units is provided with a digital display unit consisting of seven-segment display devices and a keypad which may comprise function keys and increment keys. Such a display unit and keypad are used for adjusting the light receiving sensitivity and threshold level when installing the sensor.
The photoelectric sensor units of this type are given with a higher and higher functionality so that the setting items are increased in number and are each increased in complexity. The increasing demand for space-saving and compact design has resulted in extremely small housings for such photoelectric sensor units, and the keypad and display unit particularly suffer from the impact of the compact design.
Therefore, the display unit is required to be very small, and the number of the setting keys are limited in both size and number. This has increased the difficulty in the setting and adjusting operation. In particular, as the number of sensor units increases to 16, 32 and so forth, the setting and adjusting of each key becomes progressively difficult and time-consuming.
BRIEF SUMMARY OF THE INVENTION
In view of such problems of the prior art, a primary object of the present invention is to provide a sensor system which simplifies the setting and adjustment operation for the sensor units.
Another object of the present invention is to provide a sensor system which simplifies the setting and adjustment operation for the sensor units without requiring any substantial changes to the existing structure of the overall system or the shape of the individual sensor units.
Yet another object of the present invention is to provide a sensor unit which simplifies the setting and adjustment operation for the sensor unit.
Yet another object of the present invention is to provide a mobile console which simplifies the setting and adjustment operation for the sensor units.
Yet another object of the present invention is to provide a bus unit which allows the setting and adjustment operation for the sensor units from a programmable controller, personal computer or the like connected to a field bus.
Other objects and advantages of the present invention will become obvious for a person skill in the art from the following description.
The sensor system of the present invention comprises a plurality of sensor units which are adapted to be placed closely one next to another and each assigned with an individual address, and a mobile console which is adapted to be connected to at least one of the sensor units.
As can be readily appreciated by a person skilled in the art, the “sensor unit” may comprise any sensing means having a desired sensing capability. The sensing means may consist of optical fiber photoelectric sensor units, proximate sensors and ultrasonic sensors. If the sensor unit consists of an optical fiber photoelectric sensor, the sensing means comprises light emitting means (including both hardware and software), and light receiving means (including both hardware and software). The output signal from the sensing means may not necessarily consist of a binary output (switching output) but may also consist of an analog or digital value without being converted into a binary signal. In view of the fact that they are arranged closely one next to another, the sensor units would typically consist of sensors having separate sensor heads such as optical fiber photoelectric sensors.
Being “adapted to be placed closely one next to another” includes mounting the sensor units closely one next to another on a DIN rail. However, it is also possible to use other mounting arrangements.
Being “assigned with an individual address” may include making each sensor unit identify a particular address from the relation with the adjacent sensor units according to a free allocation scheme as well as the assigning of a fixed address by using a DIP switch.
According to a preferred embodiment of the present invention, each of the sensor units forwards a handshake signal to the adjacent sensor units. From the response to the handshake signal, each sensor unit can determined if it is at the right or left terminal end or at an intermediate position, and the sensor unit at a terminal end is identified as a master unit and the remaining units as slave units, and addresses are assigned to them accordingly.
The “mobile console” means any portable console (console board). More specifically, the mobile console is at least provided with functions to enter data and read data, and to display the data.
“At least one of” means that a connection can be made to one or more of the sensor units which are arranged in a series, and it may not necessarily be located at a terminal end, but may also be located in a middle of the series. The “connection” as used herein means any connection which allows communication, and may consist of wire connection using electric cables and wireless connection using radio wave, light such as infrared light, and so on.
Each of the sensor units may comprise a connector means on each side for allowing communication with a corresponding one of the adjacent sensor units and data relaying means for transmitting data received from one of the adjacent sensor units via the corresponding connector means to the other adjacent sensor unit via the other connector means. Thereby, the bi-directional transfer of data in the manner of a bucket brigade from the mobile console to the sensor units and from the sensor units to the mobile console is enabled.
Comprising “a connector means on each side” means that each sensor is provided with two connector means corresponding to the adjacent sensor units on either side. It means that the sensor units are all connected in a series, and it is distinct from the arrangement in which the I/O units of a programmable logic controller or the like are connected in a mutually parallel relationship with respect to a system bus. However, the sensor unit which is designed to be attached to a terminal end of a sensor unit array may be provided with only one connector means because it is not required to communicate with both of the adjacent sensor units. The “connector means” as used herein means any connector which is capable of signal transmission and reception, and may include a contact-type electric connector which establishes an electric connection by the contact of a plug and receptacle, and a contact-less connector which exchanges signals by using light (infrared light).
The “data relaying means” as used herein means both the means which relays data unconditionally and the means which relays data only if it meets a certain condition. A person skilled in the art would select either one of them according to the particular need. If the unconditional data relay means is selected, the execution of the process would be simplified because of the elimination of the need to analyze the condition, but the downstream sensors would be burdened by the data relaying action which may not be necessary. On the other hand, the conditional data relay means is selected, the downstream sensors would not be burdened by the data relaying action which may not be necessary if the data is accompanied with a condition that “if the data is not intended only for the particular sensor unit”, but the execution of the process would cause a complication because of the need to analyze the condition. The “downstream” as used he
Imai Kiyoshi
Kamei Takashi
Osako Kazunori
Sato Toshinori
Nguyen Phung
Wu Daniel J.
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