This invention relates to a display unit control card and control method used in domestic appliances.
Energy is provided to the electronic control cards comprised in domestic appliances by a feeder circuit that converts the alternative current from the network to a direct current and when the network current decreases below the standards the feeder circuit, in order to stabilize the energy that it provides to the control cards, draws more current from the network. A withdrawal of a high current is also needed to illuminate the display units which inform the operator and which are used in electrical domestic appliances at low network voltage. Low voltage and high current intense electrical current, due to over heating, damages the electronic circuits such as the resistance, the diode and the coil through which the current passes. In cases where the network current is unsteady the electronic circuit elements can burn out due to over heating and may cause fire threats.
The objective of this invention is to provide a control card and a control method which ensures energy saving and maintains electronic circuit elements in cases where the network voltage is unsteady by adjusting the display units' brightness of domestic appliances according to the network voltage.
These objectives are achieved with devices and methods comprising the features of the independent claims.
A control card and a control method for domestic appliances realized in order to attain above-mentioned objects of the invention has been illustrated in the attached drawings, wherein;
The figures have been each numbered corresponding the following:
The domestic appliances, particularly refrigerators, ovens, washing machines or dish washers, comprise a control card (1) which controls its performance and a display unit (2) which displays and/or adjusts its functions.
The control card (1) comprises one or more resistances (3) which restrict the electric current, one or more diodes (4) which directs the network voltage in a half wave, one or more capacitors (5) which filters signals that are directed half waves in order to provide the direct current, a varistor (17) which normalizes high network voltage, a feeder circuit (6) which provides the direct current to the control card (1) and to the display unit (2), an input circuit (7) which transmits the signals it receives from sensors which senses the data, such as heat, light, sound, switch position, that must be sensed on the product, an output circuit (8) which enables a controlled transmission of high and low voltage which is necessary for the functioning of components, such as motor, fan, compressor, heater, lamp, that need to be controlled on the domestic appliance, a display driver circuit (12) which regulates the function of the display unit (2), a measuring circuit (13) which enables measurement of the network voltage, a memory (15) wherein the limit function value information, such as the voltage values that shall be compared with the measurable network voltage, belonging to the domestic appliance is installed and a micro processor (14) which forms the signals that increases or decreases the brightness of the display unit (2) by comparing the signals that it receives from the measuring circuit (13) with the information in the memory (15) .
The measuring circuit (13) comprises one or more resistances (23) or one or more diodes (24) which form low level and half wave or full wave directed signal required for network voltage to be measured by the micro processor (14).
Display unit (2) comprises a display screen (9) which displays information regarding the domestic appliance, one or more function buttons (10) which adjusts the functions of the domestic appliance and one or more LEDs (11) which illuminate the display screen (9) by operating in an on-off manner at a frequency that human eye could not detect.
The feeder circuit (6) in the control card (1) withdraws current above normal levels in order to provide a steady energy to the input circuit (7), output circuit (8), and micro processor (14) and to the display driver circuit (12) when the network voltage decreases below the standards. The display unit (2) being able to remain in the same brightness level at low network voltage is an important factor in high current withdrawal. In the embodiment, which is the subject of the invention, the network voltage's (Vnetwork) level is decreased by the measuring circuit (13) and it is transmitted to the micro processor (14) with half wave directing and the transmitted signals are continuously measured in the micro processor (14). Vnetwork is compared with the limit voltage values which are installed in the memory (15) of micro processor (14) and it adjusts the brightness value of the display unit (2) by determining LEDs' (11) on-off function interval ratio to each other according to the results of the above-mentioned comparison. Thus, withdrawal of high current is prevented by making the brightness of the display unit (2) compatible with the unsteady Vnetwork values.
In another embodiment of the invention the display unit (2) comprises one or more brightness adjusting buttons (16) which enable the operator to adjust the brightness manually.
The network voltage (Vnetwork) values measured by the measuring circuit (13) are compared with the limit values below which are after certain experimental studies determined by the manufacturer and installed in the memory (15).
V1: The limit network voltage value, at which the electronic circuit elements such as resistance (3) are heated above normal, is approximately 130V (e.g. in systems which have 220-230V network voltage).
V2: The limit network voltage value, at which the operation of the domestic appliance needs to be halted, is approximately 100V (e.g. in systems which have 220-230V network voltage).
The brightness values (P1, P2) of the display unit (2), which are needed to be adjusted according to the measured network voltage, are pre-installed in the memory (15) by the manufacturer.
P1: It is the brightness value assessed by determining the LEDs' (11) on/off function interval ratio to each other in order for the display unit (2) to operate under normal brightness value when Vnetwork > V1. The LEDs' (11), which have P1 brightness value, on/off function interval ratio to each other is approximately 1/50.
P2: It is the brightness value assessed by determining the LEDs' (11) on/off function interval ratio to each other in order for the display unit (2) to operate under partial brightness value (P2 < P1 preferably P2 = 0.5 P1) when the V1 > Vnetwork > V2. The LEDs' (11), which have P2 brightness value, on/off function interval ratio to each other is approximately 1/100.
The operation of the domestic appliance is halted and the display unit (2) is darkened when Vnetwork < V2.
The brightness of the display unit (2) is controlled in the following way:
As a result of making the display unit's (2) brightness compatible with the low network voltage that is below the standards, the current above normal values is not withdrawn by the main control unit (1) thus burning out due to over heating of electronic circuit elements such as resistance (3) is prevented.
Maintenance of electronic circuit elements and improvement of malfunction estimates, user safety and energy saving are provided.
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