Method for light emitting device protection and performance in an appliance

An appliance and method for variably controlling a drive signal to a light emitting device of the appliance based on a temperature value indicative of a temperature within a chamber of the appliance is provided. The light emitting device can be included in a display or disposed within a chamber of the appliance to provide illumination. The light intensity level of the light emitting device can be controlled based on the temperature value indicative of a temperature within the chamber. The temperature value indicative of a temperature within the chamber can be a value detected within the chamber, a value detected on a surface of the chamber, or a value that anticipates the temperature within the chamber. The light intensity can be controlled with a driving signal to the light emitting device. For instance, the light intensity can be controlled using pulse width modulation of the driving signal.

FIELD OF THE INVENTION

The present disclosure relates to an appliance having a light emitting device and more particularly to controlling a light intensity level of the light emitting device in an appliance using a variable driving signal.

BACKGROUND OF THE INVENTION

Appliances can include a light emitting device to transmit visual information to a user or to provide illumination within a chamber. The light emitting device can be a light emitting diode, a liquid crystal display, or other type of device that includes an element having a light intensity. The luminescence or light intensity level of the light emitting device can depend on various factors such as driving current or voltage. When the light emitting device is a light emitting diode (LED), driving the LED at a high current in a high temperature environment causes premature damage to the light emitting device.

Conventionally, light emitting devices in a display or an appliance chamber can include LEDs that are driven using a static direct drive where the current or voltage remains constant to achieve a light intensity level. A light emitting device including a LED is illumined at less than full intensity to prevent premature damage to the LED at higher temperatures. This causes the light intensity to be maintained at a low level, making it difficult for a user to read the display or see within the chamber. Increasing the light intensity level causes the premature damage to the LED because the component temperature increases as the current and voltage are increased to reach the higher light intensity level.

In another conventional approach, light emitting device in a display including a LED can be driven using a variable current. A temperature directly surrounding the LED can be detected and the light emitting diode can be driven based on the temperature detected in the area surrounding the device. However, this method increases the complexity of the detection and driving circuits and also increases the cost of the device.

While various methods for protecting light emitting diodes based on temperature are known, a need exists for an improved method of controlling a light intensity of a light emitting device in an appliance. A method of variably controlling the light intensity of the light emitting device in the appliance based on current operating conditions such as a temperature value in a chamber of the appliance would be useful. An appliance capable of increasing the light intensity while protecting the reliability of the light emitting device and adapting to various operating conditions would also be particularly useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or can be obvious from the description, or can be learned through practice of the invention.

One exemplary aspect of the present disclosure is directed to an appliance including a light emitting device configured to emit light at a light intensity level. The appliance can also include a heating element disposed in a chamber of the appliance. The appliance can also include a controller configured to receive a temperature value indicative of a temperature within the chamber, the controller configured to control the light intensity level of the light emitting device based on the temperature value.

Another exemplary aspect of the present disclosure is directed to a method of controlling the light intensity of a light emitting device of an appliance. The method includes receiving a temperature value indicative of a temperature associated with the inside of a chamber of the appliance; determining a light intensity level for the light emitting device based on the temperature value; and controlling the light emitting device to substantially achieve the light intensity level.

Another exemplary embodiment of the present disclosure is directed to an oven. The oven can include a light emitting device. The oven can further include a cooking chamber that receives items within the chamber and a heating element disposed in the cooking chamber. The heating element can provide a heat source. The oven can also include a temperature sensor coupled to the cooking chamber, where the temperature sensor provides a signal indicative of a temperature inside the cooking chamber. A controller receives the signal indicative of a temperature inside the cooking chamber, determines a light intensity level for the light emitting device based on the temperature inside the cooking chamber, and controls the light emitting device to substantially achieve the light intensity level.

DETAILED DESCRIPTION OF THE INVENTION

Generally, the present disclosure relates to an appliance and method for variably controlling a drive signal to a light emitting device of the appliance based on a temperature value indicative of a temperature within a chamber of the appliance. The light emitting device can be included in a display or disposed within a chamber of the appliance to provide illumination. The light emitting device can include a light emitting diode or other suitable light emitting device. The light intensity level of the light emitting device can be controlled based on the temperature value indicative of a temperature within the chamber. The temperature value indicative of a temperature within the chamber can be a value detected within the chamber, a value detected on a surface of the chamber, or a value that anticipates the temperature within the chamber. For instance, the light intensity level can be controlled based on a signal from a sensor that detects the temperature within the chamber. Alternatively, the light intensity level can be controlled based on a desired operation condition for the chamber. The light intensity can be controlled with a driving signal to the light emitting device. For instance, the light intensity can be controlled using pulse width modulation of the driving signal. Alternatively, the light intensity can be controlled using triac control where the triac control can provide a variable dimmer to modify the light intensity.

Referring toFIGS. 1 and 2, an oven100according to an exemplary embodiment of the present disclosure is shown. While the present disclosure will be discussed with reference to an oven, the systems and methods according to embodiments of the present disclosure are not limited to use with ovens and can be used with any other appliance having a chamber such as clothes dryers, air conditioners, refrigerators, space heaters, furnace, etc.

FIG. 1provides a front view of oven100whileFIG. 2provides a cross-sectional view. Oven100includes a door104with handle106that provides for opening and closing access to a cooking chamber105. A user of the appliance100can place a variety of different items to be cooked in chamber105. A heating element130at the top of chamber105provides a heat source for cooking. Heating element130can be any type of heating element such as gas, electric, microwave, or a combination thereof. Other heating elements could be located at the bottom of chamber130as well. Racks (not shown) in chamber105can be used to place food items at various levels for cooking within the oven. A window110on door104allows the user to view food items during the cooking process. In addition, a light emitting device (not shown) can be disposed in the cooking chamber105to provide illumination within the chamber. The light emitting device can be a LED, an incandescent lamp, a halogen lamp and/or any other suitable light emitting devices.

Oven100includes a user interface102having a display103at a top panel114with a variety of controls112. Display103can provide visual information to a user. The display103can include one or more light emitting devices such as a light emitting diode, a liquid crystal display, or any other type of light emitting device. The light emitting device can emit light at a light intensity. According to aspects of the present disclosure, the light intensity is variable with respect to a temperature associated with the inside of the cooking chamber.

Interface102allows a user to select various options for the operation of oven100, including for instance, temperature, time, and/or various cooking and cleaning cycles. Operation of oven appliance100can be regulated by a device controller125that is operatively coupled i.e., in communication with, user interface panel102, heating element130, and other components of oven100as will be further described. Alternatively, the user interface panel103can have a separate display controller that is coupled to a device controller.

In response to user manipulation of the user interface panel102, the device controller125can operate heating element130. The device controller125or the display controller can receive measurements from a temperature sensor135placed in cooking chamber105and for instance provide a temperature indication to the user with display103. Temperature sensor135can be located anywhere inside the cooking chamber105. Alternatively, temperature sensor135can be coupled with an outside surface of the cooking chamber105where the sensed temperature from the location on the outside surface of the cooking chamber105is indicative of the temperature within the cooking chamber105. In addition, an additional temperature sensor can also be located inside the appliance, for example in the interface panel102. The device controller125and/or the display controller can also be provided with other features as will be further described herein.

By way of example, the device controller125and/or the display controller can include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of appliance100. The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory can be a separate component from the processor or can be included onboard within the processor.

The device controller125can be positioned in a variety of locations throughout appliance100. In the illustrated embodiment, the controller can be located under or next to the user interface102otherwise within top panel114. In such an embodiment, input/output (“I/O”) signals are routed between the controller and various operational components of appliance100such heating element130, controls112, display103, sensor(s), alarms, and/or other components as can be provided. In one embodiment, the user interface panel102can represent a general purpose I/O (“GPIO”) device or functional block.

Although shown with touch type controls112, it should be understood that controls112and the configuration of appliance100shown inFIG. 1are provided by way of example only. More specifically, user interface102can include various input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials (knobs), push buttons, toggle/rocker switches, and touch pads. The user interface102can include other display components, such as a digital or analog display device designed to provide operational feedback to a user. The user interface102can be in communication with the controller via one or more signal lines or shared communication busses. Also, oven100is shown as a wall oven but the present disclosure could also be used with other appliances such as e.g., a stand-alone oven, an oven with a stove-top, and other configurations as well.

As stated, during operation of oven100in both cooking and cleaning cycles, the temperatures that are needed in chamber105can be high. Insulation panels124,126, and128in the bottom, rear, and top of oven100help confine heat generated within the chamber by minimizing and reducing heat transfer from oven100to e.g., surrounding cabinetry. Additionally, oven100is provided with a ventilation system whereby ambient air is used to help cool appliance100.

For instance, oven100includes air passageways118,120, and122located within the bottom, rear, and top of the cabinet101of oven100. A blower or fan116located in cavity132pulls heated air into its inlet138. This air is forced through duct136and exits oven100through vent134located between door104and top panel114. Fan116pulls air from the electronics bay (enclosure)132, which is connected with air passageways118,120,122. Cooler air from the ambient is pulled into air passageway118through air inlet108, which is located below door104. The flow of air is indicated by arrows A inFIG. 2.

The ventilation system described for oven100is provided by way of example only. As will be understood by one of skill in the art using the teachings disclosed herein, numerous other configurations can be used as well. By way of example, the flow of air can be reversed by changing the direction of operation of fan116, causing cooler air to enter at134and hot air to be exhausted at108. Different arrangements of the air passageways can also be used as well, including air passageways in the left and right sidewalls of the oven.

With reference now toFIG. 3, there is illustrated an exemplary embodiment of a schematic block diagram of an appliance display control system. The appliance display control system can include a temperature sensor135coupled to a controller320, where the temperature sensor135can be located within an appliance chamber or coupled with an outside surface of the chamber. A driver circuit330can be coupled between the controller320and a light emitting device340. The light emitting device340can be coupled to the controller320to provide a feedback signal to the controller320where the feedback can be indicative of the light intensity level at which the light emitting device340is currently operating. The light emitting device340can be included in any portion of the appliance such as in a display or disposed within the appliance chamber to provide illumination within the chamber. In addition, the light emitting device340can be an LED, an incandescent lamp, a halogen lamp, and/or any other type of light source.

Temperature sensor135can sense a temperature indicative of the temperature inside chamber105. Sensor135can be located in the chamber105and coupled to the controller320. Alternatively, the temperature sensor135can be coupled to an outside surface of the chamber. After a temperature indicative of a temperature inside the chamber is detected, the temperature sensor135can be configured to send a signal to the controller320indicative of the temperature inside the chamber105. For instance, when a user inputs a desired temperature for cooking or cleaning of the oven, temperature sensor135can detect the temperature inside the oven chamber105. As the temperature increases, the sensor135continues to monitor and communicate the present temperature detected inside the chamber105.

Alternatively, rather than an actual temperature reading, the display controller320can generate a signal from memory indicative of an anticipated temperature inside the chamber. The anticipated temperature can be a predetermined temperature and the signal indicative of the anticipated temperature inside the chamber can be communicated to the controller. The signal can include a predetermined function such as an equation, lookup table, or algorithm that correlates to the anticipated temperature inside the chamber105. In addition, this signal can include information representing a time interval, where the time interval can be indicative of how long it will take to reach the predetermined temperature within the chamber. This information representing a signal indicative of a temperature within a chamber can be transmitted from memory to the processor of the display controller.

The controller320can provide a driving signal to the light emitting device via the driver circuit330to control the light intensity level of the light emitting device340. The light intensity level can be dynamically or variably determined by the controller320according to the temperature value indicative of the temperature inside the chamber105.

The light emitting device340can include one or more light emitting devices. For instance, the light emitting device can include more than one light emitting diode. Each light emitting device can be variably controlled or all the light emitting devices can be controlled uniformly.

In one embodiment, controller320can determine a first light intensity level when the temperature value is greater than a predetermined threshold. A second light intensity level can be determined when the temperature value is less than a predetermined threshold. Alternatively, the current light intensity level can be maintained when the temperature value is substantially equal to the predetermined threshold. The predetermined threshold can be a single temperature value or a temperature range.

The controller320can send a signal indicative of the light intensity level to the driver circuit330. Based on the command from the controller, the driver circuit330can drive the light emitting device340in various ways such as using direct drive or pulse width modulation. In direct drive methods, the driver circuit330can supply a percentage of desired current or voltage for the time interval the light emitting device340is driven at the driving signal. For instance, to achieve a reduced light intensity level, the maximum current or voltage could be applied constantly at a reduced magnitude.

Alternatively, using pulse width modulation, light emitting device340can be driven by modifying the duty cycle of the signal. A duty cycle is a ratio between the duration a signal pulse is in the active state to the total period of the signal. For example, to achieve a reduced light intensity level, a maximum current or voltage signal could be applied to the light emitting display at a reduced duty cycle.

In an alternative embodiment, the driver circuit330can include a control triac (not shown). A control triac can be used as a variable dimmer to control the light intensity of the light emitting device340.

FIGS. 4 and 5illustrate exemplary embodiments of a schematic block diagram of the appliance display control system.

As shown inFIG. 4, the temperature sensor135can sense the temperature indicative of the temperature within the chamber of the oven. The controller320receives a signal indicative of the temperature within the chamber and sends a signal to the driver circuit330to achieve a first light intensity level (L1). Driver circuit330generates a signal335having a duty cycle as illustrated inFIG. 4. The light emitting device340receives the signal335and the light emitting device340emits light at a first light intensity level345.

As shown inFIG. 5, the temperature sensor135senses a temperature greater than the temperature sensed inFIG. 4. The controller320receives the signal indicative of the higher temperature within the chamber and sends a signal to the driver circuit330to achieve a first light intensity level (L2), which is less than the first light intensity level (L1). The driver circuit330generates a signal336having a duty cycle less than signal335, as shown inFIG. 5. The light emitting device340receives the signal336and the light emitting device340emits light at a second light intensity level346.

A signal335, as shown inFIG. 4, can be supplied to light emitting device340using pulse width modulation to control the light intensity level345. As previously discussed, the duty cycle directly correlates to the light intensity levels. Therefore, when a signal336having a lesser duty cycle, as shown inFIG. 5, is supplied to the light emitting device340, the light emitting device340is driven to produce an output having a lesser light intensity level346than that ofFIG. 4.

FIG. 6illustrates a flow chart of an exemplary method600according to an exemplary embodiment of the present disclosure. The method600will be discussed with reference to the exemplary appliance light emitting device control system illustrated inFIGS. 3-5. However, the method600can be implemented with any suitable appliance display control system. In addition, althoughFIG. 6depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods can be omitted, rearranged, combined and/or adapted in various ways.

The temperature value indicative of a temperature within the chamber of the appliance is received by the controller320at (610). This temperature value could be transmitted from a temperature sensor135located within a chamber or coupled with an outside wall of the chamber. Alternatively, it could be a signal produced by the controller320based on an anticipated temperature profile inside the chamber. The controller320can determine in (620) to change in light intensity level of a light emitting device based on signal indicative of a temperature within the chamber and a feedback from a light emitting device340. The light intensity level can be determined through various methods, such as a lookup table, an equation, or an algorithm.

The controller320sends a signal to the driver circuit330to control the driving signal to substantially maintain the current light intensity level at (625). For the purpose of this application, “substantially” means within 10% of the intended control level.

When the controller320determines that the signal indicative of a temperature in a chamber indicates a change in light intensity, the indicated change in light intensity is compared with a predetermined threshold in (635). The predetermined threshold can be a single value or a range of values.

When the indicated light intensity is greater than the predetermined threshold, the controller320can control the driver circuit330to increase the light intensity level in (640) and substantially maintain the new light intensity level of the light emitting device340. When the indicated light intensity is less than the predetermined threshold, the controller320can control the driver circuit330to decrease in light intensity level in (650) and substantially maintain the new light intensity level of the light emitting device340. Method600can be performed once or a plurality of times during an operational cycle, where an operational cycle can be a portion or an entire heating cycle corresponding to a user input.