Abstract:
A knob assembly includes a repositionable knob having an interior framework and a light-transmissive indicia, at least one light source for projecting light into the knob to back-illuminate the indicia, a position sensor for providing an output dependent on the position of the knob, and a controller receiving the output from the sensor and controlling the intensity of the at least one light source to compensate for any light blocked by the interior framework, and maintain a substantially uniform illumination of the light-transmissive indicia so that it is viewable from the exterior of the knob.

Description:
BACKGROUND 
     Household appliances, examples of which may include a clothes washer, clothes dryer, an oven, a cooktop, a refrigerator, or a dishwasher, etc., perform useful cycles of operation and often have electrical and mechanical components responsible for implementing the cycle of operation of the appliance, with one or more of the components controlling the operation of the other components. For example, a controller, such as a microprocessor-based controller, having a printed circuit board (PCB) with memory, may be used to control the operation of the various components to implement a cycle of operation. 
     A Human Machine Interface (HMI) (a/k/a User Interface) may be provided as part of or separate from the controller to provide input/output communication between a user of the appliance and the controller. One or more knob assemblies are often part of the HMI to provide a way for the human to provide input to the HMI. 
     SUMMARY 
     A knob assembly comprising a rotatable knob, a light-transmissive indicia provided on the knob, multiple lights sources, a position sensor providing a position output indicative of the rotational position of the rotatable knob and a controller. The controller receives the position output and is operably coupled to the light sources to independently control the intensity of light transmitted by the multiple light sources. The controller uses the position output to determine whether the structural frame will block the light transmitted from any of the multiple light sources to the light-transmissive indicia and controls the intensity of the multiple light sources to compensate for any blocked light to maintain a predetermined backlighting of the light-transmissive indicia. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the drawings: 
         FIG. 1  is a side, cross-sectional view of a first embodiment of a knob assembly according to the invention, with the knob assembly comprising a knob and a rotary encoder. 
         FIG. 2  is a top view of the knob of a second embodiment. 
         FIG. 3  is a top view of a knob of a third embodiment. 
         FIG. 4  is a side, cross-sectional view of a fourth embodiment of a knob assembly of the invention. 
         FIG. 5  is an enlarged view of  FIG. 4  of a light source of the fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a human user interface  10  is shown and includes a controller in the form of a PCB  12  with a microprocessor  14 , a fascia  16  overlying the PCB  12 , and a knob assembly  18  carried by the PCB  12  and extending through the fascia  16 . 
     The knob assembly  18  comprises a repositionable knob, illustrated as a rotatable knob  20 , at least one light source illustrated as multiple light sources  22  each having a light emitter  60 , with corresponding light guides  24 , and a position sensor, which is illustrated as a rotary encoder  26 . The rotatable knob  20  comprises an outer surface  28  and an inner surface  30  defining an interior  32 . A light-transmissive indicia  36  is provided on the knob  20  and viewable from the outer surface  28 . A structural framework  34  is located within the interior  32  to provide structural support to the knob  20 . The structural framework  34  may be of any desired structure. However, in many implementations, it is a hub  38  and spoke  40  structure. The structural framework  34  may also vary in thickness. 
     The light sources  22  and rotary encoder  26  are mounted to the PCB  12 , which, as illustrated, is on a rear side  42 , but could just as easily be mounted to a front side  44  of the PCB  12 . The light guides  24  extend through an opening in the PCB  12  and the fascia  16 , and direct the light emitted by the light source  22  from the rear side  42 , through the PCB  12  and fascia  16 , and into the interior  32  of knob  20 . In alternate embodiments, at least some of the light sources  22  may be mounted to a front side  44  of the PCB  12 . 
     The rotary encoder  26  includes an encoder body  50 , defining an interior  52 , and a rotatable shaft  54 , mounted to the body  50  for relative rotation. The knob  20  is mounted to the rotatable shaft  54 . The shaft  54  has one end fixedly mounted to the structural framework  34  and another end rotatably mounted to the PCB  12 . The knob  20  is typically mounted to the shaft  54  to prevent relative rotation between the shaft  54  and knob  20 . The encoder body  50  may be mounted, such as by soldering, to the PCB  12 . 
     The encoder body  50  may be operably coupled to the microprocessor  14  via a conductive trace on the PCB  12 . The rotary encoder  26  may be configured to transform the rotational position of the shaft  54  into electrical signals, which may output to the microprocessor  14  along the trace. The electrical signals may directly indicate a selection by the user or may be used by the microprocessor  14  to determine the selection by the user. 
     The encoder  26  may be a hollow-shaft rotary encoder or any other suitable type of encoder. Further, the encoder  26  may be implemented as either an absolute or a relative rotary encoder. The encoder  26  may have its own circuit board and processor to determine the rotary position of the shaft  54  and/or knob  20 . The circuit board of the encoder  26  may be connected to the microprocessor  14 . The rotary encoder  26 , PCB  12 , light guide  24 , and light source  22  collectively define the major element of a rotary encoder assembly. 
     The knob  20  and shaft  54  may have various shapes and/or designs. By way of non-limiting examples, the knob  20  and shaft  54  may be a singular piece or may alternatively be operably coupled together in a suitable manner. The knob  20  may have an axis about which it rotates and it is contemplated that regardless of the configuration of the knob  20  and shaft  54 , the rotational axis of the knob  20  may be collinear with a rotational axis of the shaft  54 . 
     The light transmissive indicia  36  may comprise an insert provided in the rotatable knob  20  and may be of different color, material, and/or transmittance than that of knob  20 . The light transmissive indicia  36  may comprise multiple light transmissive indicia  36 , with the predetermined backlighting highlights one or all of the multiple light transmissive indicia  36 . In alternate embodiments, the knob  20  or the indicia  36  may comprise a light diffuser (not shown) to spread out or scatter the light in the interior  32  of knob  20 . 
     The light sources  22  are located relative to the rotatable knob  20  and below at least a portion of the structural framework  34  to transmit light into the interior  32  of the knob  20  past the structural framework  34  to backlight the light-transmissive indicia  36 . At least some of the light sources  22  and/or light guides  24  may be mounted directly below the interior  32  of knob  20 . Light sources  22  may be light emitting diodes (LEDs) or alternative light emitting devices. The structural framework may be of a transparent or semi-transparent material to better allow light to pass through to the indicia  36 . 
     Each light source  22  may be of a single color or multiple colors. For single color, a single color LED is contemplated. For multiple colors, a multiple color LED, like a tri-colored LED, is contemplated. The microprocessor  14  may control the mixing of light from each light source  22  to create custom color(s) dependent on the rotary position of knob  20 . The microprocessor  14  may execute a suitable program that is configured to select the color based on the rotational position. 
     A predetermined backlighting may be applied to the light transmissive indicia  36  based on the rotational position of the knob  20 . The microprocessor  14  uses the rotational position of the knob  20  to determine the intensity and/or color of each of the light sources  22  to generate the predetermined backlighting, which is accomplished by an algorithm being implemented as a computer program being executed by the microprocessor  14 , with the algorithm using the rotational position of the knob  20  as input. By predetermined backlighting, it is meant that at least the intensity of the light, and optionally the color, of the light sources is controlled so that a predetermined backlight pattern is applied to the light-transmissive indicia  36 . One such predetermined backlighting is one that provides the light-transmissive indicia with  36  a substantially even backlighting when viewed from the outer surface  28  of the knob  20 . 
     While an even distribution of light may seem simple at first, when one realizes that the structural framework  34  will block one or more of the light sources  22 , an even distribution becomes more complicated because the intensity must be varied to compensate for the blocked light sources  22 . The problem is further exacerbated in that the effected light sources  22  and the amount of blockage is dependent on the rotational position of the knob  20 . The invention solves this problem by using the rotational position of the knob to determine which light sources  22  are blocked and the degree of blockage of each of the blocked light sources  22  and thereby determine the intensity level for each of the light sources to obtain an even distribution. The microprocessor  14  then uses this information to control the intensity of the light sources  22 . 
     One method for implementing the invention can be a data table having corresponding intensity levels for a plurality of rotational positions. In such a scenario, the microprocessor  14  receives the position output and operably coupled to the multiple lights sources  22  to independently control the intensity of light transmitted by the multiple light sources  22  according to the intensity values for the corresponding rotational position. In such a solution, it is inherent that the data table values take into account the position of the structural framework  34  relative to the corresponding rotational position. These relationships can be determined by suitable testing for a given structural framework  34  in a particular knob  20 . A different data table may be provided for different knobs  20 /structural framework  34 . 
     An alternative would be to provide a map of the structural framework relative to the rotational position of the knob. The algorithm could then take into account the rotational position from the encoder  26  and the corresponding location of the structural framework  34  based on the map and use these to determine the intensity of illumination for the light sources  22  to obtain the even distribution. 
     The intensity of each light source  22  may be individually controlled to obtain the desired backlighting. In some cases it may be necessary to increase the intensity of one or more of the light sources  22  while decreasing the intensity of the other light sources. For example, when a light source is partially blocked by the structural framework, the intensity of that light source may be increased. If the intensity increase is not sufficient to obtain the even distribution, for example, the intensity of the light sources may be reduced to obtain an overall even distribution. 
     The predetermined backlighting may include other types of backlighting than an even distribution. Another example of backlighting is one that highlights the user selection while evenly backlighting the rest of the knob  20 . As with the prior example, the data table would have rotational positions corresponding to the predetermined user selections and the corresponding intensity levels for each of the light sources  22 . The intensity levels could be determined by testing and a data table provided for a particular knob  20 /structural framework  34 . Other predetermined backlighting scenarios are contemplated. 
     Referring now to  FIG. 2 , a second embodiment of knob assembly  110  is illustrated. Like parts between the second and first embodiments will use the same numbers with a 100 prefix. The second embodiment knob assembly  110  is similar to the first embodiment, except that the hub/spoke structural framework  134  has a more complex shape which can be thought of in terms of the transmissible nature of the materials. The structural support may be thought of as the least transmissive or even opaque areas, collectively referred to as low transmissive areas  186 , whereas the indicia  136  may be thought of as the more transmissible areas. The indicia  136 , illustrated as a spiral, and the multiple light sources  122  are positioned about the shaft  154  in a circular fashion, resulting in the indicia  136  being non-symmetric relative to the circularly arranged light sources  122 . The indicia  136  may be unevenly illuminated due to the blockage of the light sources  122  by low transmissive areas  186 , which may be opaque. As illustrated, some light sources  122  are covered more than other light sources  122  by the low transmissive area  186 . Each light source  122  is controlled independently. Based on the rotational position of the knob  120 , the intensity of the light from the light sources  122  will be adjusted. For example, if a single light source  122  is known to be partially or completely blocked by a low transmissive area  186 , the intensity of light source  122  can be increased to better provide a more evenly illuminated indicia  136 . If the increase in intensity of the blocked light source  122  is insufficient for an even distribution, then the intensity from one or more of the other light sources  122  may be reduced. 
       FIG. 3  illustrates a third embodiment of a knob assembly  18 . The third embodiment is similar to the first and second embodiments, with the primary difference being the third embodiment has an outer surface  228  which is primarily made up of multiple, discrete indicia  236 . For the most part, like parts between the two embodiments will be identified with like numerals, with the numerals of the third embodiment having the 200 prefix. Each indicia  236  is of a pie-shaped design wherein each pie section is directly over one light source  222  for at least one rotational position. It is contemplated that the rotation of the knob assembly  18  is indexed such that the knob assembly  18  may be rotated through discrete rotational positions. In each of the positions, each of the pie sections will overlie a light source  222 . To indicate which of the rotational positions is “selected” by the user based on the rotation of the knob assembly  18 , the selected indicia  236  will be illuminated, either brighter or dimmer, than the other indicia  236 , with it being brighter in most cases. To make the selected indicia brighter, the light source  222  underlying the indicia  236  may be increased in intensity and/or the other light sources may be decreased in intensity. The selected indicia  236  will result in a single, substantially brighter illuminated, area  284 . This may function to visually display to the user which function the knob assembly  18  is selecting. 
     In the scenario of the third embodiment, knob assembly  218  is likely to be configured to have discrete stops or detents to provide tactile feedback to the user of their selection. The corresponding data table would include a list of rotational positions and the corresponding intensity levels for each of the light sources  122 . The intensity levels would take into account and compensate for any structural framework, which would likely comprise walls extending radially outwardly from the center of the knob  220 , along the sides of the pie-shape sectors, as well as take into account the additional intensity needed for area  284  to be substantially brighter. 
       FIG. 4  illustrates a fourth embodiment of a knob assembly  318 . For the most part like parts between the embodiments will be identified with like numerals, with the numerals of the prior embodiments having the 300 prefix. A human user interface  310  is shown and includes a controller in the form of a PCB  312  with a microprocessor  314 , and a fascia  316  overlying the PCB  312 . The fourth embodiment is similar to the prior three embodiments, with the primary difference being the fourth embodiment has side-firing light sources  322 , located on a rear side  342  of the PCB  312  with corresponding light guides  324 , which emit light into and interior  332  of the encoder  326 . The side-firing light sources  322  could just as easily be mounted to a front side  344  of the PCB  312 . This side-firing configuration may be used with any of the embodiments. 
     In the fourth embodiment, the rotatable knob  320  comprises an outer surface  328  and an inner surface  330  defining an interior  332  with a structural framework  334  located within the interior  332 , and a light-transmissive indicia  336  provided on the knob  320  and viewable from the outer surface  328 . Light sources  322  comprise a light emitter  360 . Light sources  322  may be LEDs or alternate light emitting devices. 
     The rotary encoder  326  comprises a body  350  defining an interior  352 , and a rotatable shaft  354  supported by the body  350 . A light guide  374  may be provided within the shaft  354  or integrally formed with the shaft  354 . The rotatable knob  320  is fixedly mounted to the rotatable shaft  354  to effect rotation of the knob  320 . The body  350  comprises at least one window  362  corresponding to the at least one light sources  322  through which light emitted from the light sources  322  is transmitted to the interior  352 . The body  350  may comprises a peripheral side wall and the windows  362  may be spaced about the peripheral sidewall. The light sources  322  correspond to windows  362  and optically couple the body interior  332  to the knob interior  332 . Wherein the light emitted exteriorly of the body  350  from one of the light sources  322  passes through the corresponding window  362  and is transmitted by the corresponding light guide  374  from the body interior  352  to the knob interior  332 . 
       FIG. 5  illustrates an enlarged view of the light source  322  and encoder body  350  to illustrate the relationship between the light emitted from the light source  322  and the windows  362 . The light source  322  emits a light having a beam angle  364 . The at least one light source  322  and at least one window  362  are relatively positioned such that an arc segment defined by the beam angle  364  passes through the at least one window  362 , which ensures that the greatest amount of light is provided to the interior  332  of the encoder  326 . The beam angle  362  is the degree of width that light emits from a light source  322 . In specific terms this is the angle between the opposing points on the beam axis where the intensity drops to 50% of its maximum. The beam angle  364  may be larger than the window  362  if the light source  322  is not immediately outside of the window  362 . In alternate embodiments, the light source  322  may be closer to or enclosed by the encoder body  350  and light emitter  360  may be located within the window  362  in order to reduce light bleeding away from the encoder  326 . 
     While the window  362  is illustrated as an opening in the encoder body  326 , the window  362  may be a transmissive portion in the encoder body. As a transmissive portion, it may be either translucent or transparent. The transmissive portion may also be colored to alter the color of the emitted light. It is further contemplated that the window  362  may essentially be an opening in the body  326  in which a window “pane” is provided, with the pane providing the transmissive portion, for example. 
     While various embodiments of the application have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.