Optical waveguides – With optical coupler – Switch
Reexamination Certificate
1999-02-05
2001-03-13
Sanghavi, Hemang (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S016000, C340S815480, C340S815490
Reexamination Certificate
active
06201905
ABSTRACT:
The present invention relates generally to switches and, more particularly, to switches for controlling the speed and direction of movement, and other operations of motor driven hoist cranes and the like. More specifically, the invention concerns switches of the push button type wherein each push button may be manually depressed to each of a plurality of positions in order to thereby produce a variable control signal, which is proportional to the positioning of the push button, for operations such as, for example, the speed of movement of a hoist crane in the vertical direction. In particular, the invention pertains to improvements in so-called non-contact optical switches of the above class.
Examples of non-contact optical switches of the foregoing class of switches are disclosed in U.S. Pat. Nos. 5,321,311; 5,272,383; and 4,816,671. Typically, a plurality of these switches are incorporated in a switch panel with each switch comprising a separate module, each module housing a pair of push button mechanisms and associated electronics.
Heretofore, non-contact optical switches, including those disclosed in the above-referenced patents, have been complex structures incorporating numerous parts and involved circuitry. For example, the switches disclosed in the above patents depend on electronics incorporating discrimination capability to prevent erroneous output signals such as would occur, for example, if the operator depressed both push buttons simultaneously.
Additionally, non-contact optical switches presently utilize digital output codes to control the speed of motors for equipment such as overhead cranes. These switches use light transfer through a plurality of apertures to create a finite group of output codes capable of controlling a set of motor functions. For example, the first output code would cause the motor to decelerate, the second output code would hold the current motor speed, and the third output code would cause the motor to accelerate. Therefore, various motor speeds can be achieved by accelerating and decelerating the motor to the desired speed and then holding that speed. The problem with these switches is that it is time consuming and sometimes difficult to achieve desired motor speeds.
An object of the present invention is to provide a switch module of the foregoing type having a much simplified, and consequently much less expensive, construction and mode of operation.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, an optical switch of the push button type for producing a variable control signal which is proportional to the position of the push button includes a housing, having a first interior wall and a second interior wall, and a push button which extends into the interior of the housing from the exterior thereof. The push button includes a body portion disposed within the housing for movement through each of a plurality of positions, whereby changes in the position of the push button cause proportional changes in an output voltage produced by the switch. A stationary light shield, which includes a plurality of apertures, is fixedly disposed within the housing between the body portion of the push button and the first interior wall of the housing. Light emitting means are disposed within the housing and between the stationary light shield and the first interior wall. Light responsive means are fixedly disposed between the stationary light shield and the body portion of the push button. The light emitting means and the light responsive means are each in optical alignment with the apertures of the stationary light shield. A shutter is associated with the body portion of the push button and is responsive to movement of the body portion of the push button. The shutter also includes a plurality of apertures which allow the shutter to adjust the amount of light permitted to pass through the shield apertures.
In a preferred embodiment the light responsive means comprise an array of photo diodes and photo transistors.
In accordance with another aspect of the invention, an optical switch incorporates a switch module. Two push buttons extend into the interior of the switch module housing from the exterior thereof. Each button has a body portion disposed within the housing for movement through each of a plurality of positions. Stationary light shields are fixedly disposed in spaced apart relation within the housing, each of the shields having a plurality of apertures. First and second light emitting means are fixedly disposed within the housing between the shields, the first of the light emitting means being in optical alignment with the apertures of one of the shields, and the second of the light emitting means being in optical alignment with the apertures of an other of the shields. First and second light responsive means are fixedly disposed in spaced apart relation within the housing with the shields and the first and second light emitting means being disposed therebetween, with the first of the light responsive means being in optical alignment with the apertures of one of the shields, and the second of the light responsive means being in optical alignment with the apertures of another of the shields. First and second shutters are disposed within the housing with each of said shutters having a plurality of apertures. The first shutter is associated with the body portion of one of the push buttons and is responsive to movement thereof which thereby adjusts the amount of light permitted to pass through the apertures of one of the shields. The second shutter is associated with the body portion of the other of the push buttons and is responsive to movement thereof which thereby adjusts the amount of light permitted to pass through the apertures of another of the shields. Depending on the position of the push button and its shutter, varying amounts of light pass through to the light responsive means. Based on the amount of light received by the light responsive means, the control signals are increased or decreased proportionally. The amount of light which passes through the shields is increased proportionally by providing at least one aperture with a varying area. The size of this aperture is a product of a stationary shield aperture, which does not vary, and a correlating shutter aperture which varies in size. Moreover, the size of the shutter aperture changes as the push button is moved up or down because the shutter aperture, which extends vertically and which is comprised of varying horizontal widths, sweeps across the stationary shield aperture which is constant. Thus, as the shutter is adjusted in relation to the stationary light shields, the size of and the amount of light which passes through the aperture formed by the shutter aperture and the shield aperture is also changed.
In addition, an intensity control feedback circuit is provided to ensure that the photo diode voltage which determines the LED intensity always matches the reference voltage, regardless of any malfunctions such as LED output degradation versus time, LED output degradation versus temperature, and aperture misalignments.
Also, a safety control circuit is provided which prevents malfunctions due to depression of multiple push buttons. Specifically, if one push button is depressed, the other push button is disabled, and if both push buttons are depressed, both push buttons are disabled.
In a preferred form each of the light responsive means comprise a plurality of photo diodes and photo transistors and each of the light emitting means comprise a plurality of light emitting diodes. The output of the photo transistors determines the overall functionality of the switch.
The features of the present invention are discussed in more detail below, and it is not intended that the summary presented hereinabove should in any way limit the nature or scope of the invention disclosed and claimed herein.
REFERENCES:
patent: 1886517 (1932-11-01), Batcheller
patent: 2385165 (1945-09-01), Sears
patent: 2480410 (1949-08-01), Hammerly
patent: 2806907 (1957-09-01), Mazzola
patent: 30
Carrillo Michael
Doan Jennifer
Galis Mark
Jarosik Gary
Sanghavi Hemang
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