JPH0680125U - Luminance adjusting device for electroluminescent device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a brightness adjusting device for an electroluminescent element, which is used as illumination or display means for a vehicle instrument equipped with an electric integrating meter and is turned on by an inverter, a change with time of the electroluminescent element. The accompanying decrease in brightness is adjusted by varying the voltage of the inverter according to the distance traveled by the electric integrating meter. The EL control section D includes a voltage variation circuit 7 that varies the voltage according to a brightness adjustment signal f from the CPU 3 that calculates the travel distance of the electric integrator A, and an inverter that varies the voltage according to the voltage variation signal g. And 8 The brightness adjusting device C comprises an EL control section D and an EL element 9 for uniformly illuminating the display section of the meter from below.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a brightness adjusting device for an electroluminescent element (hereinafter abbreviated as EL element) used for illumination and display means of a vehicle instrument equipped with an electric integrating meter.

[0002]

[Prior art]

 Conventionally, an EL element has been used as a display device or a lighting device of a vehicle meter, but it is known that the EL element has a reduced emission brightness (deterioration of the EL element) due to aging. As conventional examples in consideration of such problems, there are, for example, Japanese Utility Model Laid-Open No. 62-11199 and Japanese Patent Laid-Open No. 64-67891, the former having a sensor for detecting the light emission luminance, The light emission brightness of the EL element is adjusted by changing the output signal from the drive circuit to the EL element according to the output.The latter detects the input current with the current detection circuit and detects the input current of the transistor (switching circuit). Negative feedback to the base, the base potential of the transistor is controlled, and the input current of the inverter is approximated to a constant state over time, so that the fluctuation of the output voltage of the inverter is increased. It is set to prevent the brightness of the EL element from decreasing.

[0003]

[Problems to be solved by the device]

 However, the former requires a space for arranging a sensor for detecting the light emission brightness, and there is a problem that the appearance of a lighting device or a display device for a vehicle having a limited space is impaired. Had a problem that the drive circuit had a complicated configuration because a current detection circuit for negatively feeding back the current was required.

[0004]

[Means for Solving the Problems]

 The present invention relates to a brightness adjusting device for an electroluminescent element, which is used as illumination or display means for a vehicle instrument equipped with an electric integrating meter and is turned on by an inverter, and reduces a decrease in brightness due to a change with time of the electroluminescent element. A voltage fluctuation circuit for controlling the voltage of the inverter according to the traveling distance of the electric integrator is provided to adjust the light emission brightness.

[0005]

[Action]

 The luminescent distance of the EL element can be adjusted by the voltage fluctuation circuit that outputs the signal associated with the mileage by the mileage control unit of the electric integrator and changes the applied voltage according to the signal. It is possible to maintain excellent emission brightness of the EL device.

[0006]

【Example】

 Hereinafter, a brightness adjusting device for an EL device according to the present invention will be described with reference to the accompanying drawings. In the following, a vehicle illumination device equipped with an electric integrating meter is shown as an example.

FIG. 1 is a block diagram showing a circuit configuration of the present invention. In the figure, an electric integrator A includes a pulse oscillating circuit 1 that outputs a pulse signal a according to the rotation of a wheel, and a predetermined traveling distance when the number of pulses corresponding to the predetermined traveling distance is reached by counting the pulse signal a. In order to store the contents of the arithmetic processing, the CPU 3 for calculating the accumulated traveling distance by arithmetically processing the traveling signal b from the counter 2 for outputting the traveling signal b and the traveling signal b from the counter 2 and the memory section 4 described later. A running distance control unit B including a memory unit 4 composed of a non-volatile memory (EEPROM), a driver 5 for converting a calculation processing data signal d from the CPU 3 into a displayable signal e, and a running distance are displayed. It is composed of a display unit 6.

On the other hand, the brightness adjusting device C for a vehicle meter changes the voltage according to the brightness adjusting signal f from the CPU 3 by a driving circuit (not shown) including a capacitor, a transistor, a resistor, etc., and outputs a voltage changing signal g. An EL control section D including a voltage fluctuation circuit 7 and an inverter 8 for converting the voltage fluctuation signal g into a voltage for driving an EL element 9 which will be described later, and a display section of a meter (not shown) are uniformly arranged from below. It is composed of an EL element 9 for illuminating.

According to this configuration, when the CPU 3 counts the pulse signal a oscillated by the pulse oscillating circuit 1 with the counter 2 and rewrites the data at a predetermined traveling distance, the traveling signal b of the counter 2 and the memory section 4 are used. After processing the running memory data signal c, the processing data signal d is output to the driver 5, which is converted into a signal e which can be displayed by the driver 5, and the running distance is displayed on the display unit 6. To be done. In addition to the calculation processing of the travel distance, the CPU 3 outputs the brightness adjustment signal f when the travel distance reaches an arbitrary travel distance in order to consider the decrease in the emission brightness due to the change over time of the EL element 9. The fluctuating circuit 7 outputs the voltage fluctuating signal g to the inverter 8 by changing the resistance and the capacitor of the driving circuit (not shown) in order to convert the voltage fluctuating signal g into the voltage corresponding to the brightness adjusting signal f. Applies a voltage according to the voltage fluctuation signal g to the EL element 9 to adjust the emission brightness.

Next, the specific adjustment of the present embodiment will be described with reference to the characteristic diagram of FIG. 2. The horizontal axis represents the traveling distance (10,000 km) of the vehicle and the operating time (hr), and the vertical axis. Represents emission brightness (cd / m ² ).

For example, when an EL element 9 as shown in FIG. 1 having a light emission luminance characteristic such as E1 is used depending on the lighting time (the lifetime of the EL element 9 is 5000 hours, a normal vehicle lifetime travel distance is 100,000). The CPU 3 outputs a brightness adjustment signal f at every predetermined distance of 10,000 km, and gradually increases the voltage applied by the inverter 8 to the EL element 9 in proportion to the traveling distance. As described above (for example, considering the withstand voltage of the EL element 9 and increasing the initial applied voltage by 10% at every 10,000 km), the voltage fluctuation circuit 7 outputs the voltage fluctuation signal g. Is like E2, which means that sufficient emission brightness can be obtained when the vehicle has reached the lifetime mileage.

Further, if the predetermined traveling distance is subdivided and the luminance adjustment signal f from the CPU 3 is output, the emission luminance becomes E3, and the luminance adjustment can be performed without a feeling of strangeness.

In order to manage and adjust the light emission brightness of the EL element 9 by the lighting time, by providing and controlling a timer circuit (not shown) for measuring the usage time of the EL element 9, the EL elements other than those for vehicles are controlled. It goes without saying that it can be used as a brightness adjusting device for the element 9.

[0014]

[Effect of device]

 The present invention relates to a brightness adjusting device for an electroluminescent element, which is used as illumination or display means for a vehicle instrument equipped with an electric integrating meter and is turned on by an inverter, in which a decrease in luminance due to a change with time of the electroluminescent element. Is equipped with a circuit that controls the voltage of the inverter according to the distance traveled by the electric integrator and adjusts the light emission brightness. In addition to prolonging the service life of vehicle meters (products) that use EL elements, it is possible to reduce the cost because the circuit configuration is simple.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of this embodiment.

FIG. 2 is a characteristic diagram showing the emission brightness of the above-mentioned embodiment.

[Explanation of symbols]

 1 pulse oscillating circuit 2 counter 3 CPU 4 memory unit 5 driver 6 display unit 7 voltage fluctuation circuit 8 inverter 9 EL element A electric integrating meter B mileage control unit C lighting device DEL control unit

Claims (1)

[Scope of utility model registration request] 1. A brightness adjusting device for an electroluminescent element, which is used as illumination or display means for a vehicle instrument equipped with an electric integrating meter and is turned on by an inverter, wherein the brightness of the electroluminescent element decreases with time. 2. A brightness adjusting device for an electroluminescent device, comprising a voltage fluctuation circuit for controlling the voltage of the inverter according to the traveling distance of the electric integrator.