JPH0367891B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention applies to automobiles that use different types of light emitting elements such as lamps, fluorescent display tubes (hereinafter referred to as FLT), and light emitting diodes (hereinafter referred to as LED) for display, lighting, etc. The present invention relates to a device for adjusting the brightness of each light emitting element in a display device.

(Prior Art) Automotive display devices such as electronic meters use FLTs, LEDs, and other light emitting elements as display elements for vehicle speed, engine speed, remaining fuel level, clock, etc.
Furthermore, some devices are equipped with different types of light emitting elements, such as lamps used to illuminate the display area (so-called instrument panel area). The display element described above needs to have a high display brightness during the day and a low brightness at night, and it is also necessary to adjust the brightness according to the brightness of the lighting lamp, which can be adjusted according to the driver's preference. Need to adjust. This problem can be solved by providing an adjustment mechanism for each light emitting element that the driver operates as a means for making these adjustments, but this is not practical due to cost and extra burden on the driver.

It is also known that one way to adjust the brightness of a light emitting element is to adjust and change the duty ratio (ratio of lighting energization time per unit period) of the driving pulse signal of the light emitting element, but depending on the type of the light emitting element, Since the luminance duty ratio characteristics are different, it is inconvenient to directly drive various light emitting elements with a common duty ratio because it may result in a display with poor luminance balance.

Therefore, as shown in Japanese Patent Publication No. 59-763, a method has been proposed in which the brightness of one light emitting element can be adjusted by changing one duty ratio, and the brightness of other types of light emitting elements can also be adjusted. ing.
This involves changing the duty ratio of a pulse signal with a constant frequency (280Hz) using a rheostat or the like to obtain the required lamp brightness, and then inputting the pulse signal to a duty ratio conversion circuit section consisting of a delay circuit and a waveform shaping circuit. Create an FLT drive signal to obtain the required FLT brightness, further provide a duty ratio conversion circuit section for the LED, receive the FLT drive signal and obtain the LED drive signal with the required duty ratio, It is designed to obtain the required LED brightness.

(Problems to be Solved by the Invention) The invention of Japanese Patent Publication No. 59-763 mentioned above changes the duty ratio of a drive pulse signal in order to adjust the brightness of one light emitting element, and generates a pulse with a changed duty ratio. Since the device receives a signal and changes it into a drive pulse signal with a predetermined duty ratio required by other light emitting elements using a predetermined circuit, frequency accuracy is required for the first adjustment pulse signal. Ru. In other words, delay circuits etc. for converting the duty ratio are only possible because the input is at a predetermined frequency, and their purpose is achieved.If only the duty ratio is changed, the brightness can be adjusted even if the frequency changes slightly. Although this objective can be achieved, the above-described method requires a duty ratio adjustment mechanism that requires even frequency accuracy when operating and adjusting the duty ratio.

(Means for Solving the Problems) Therefore, the present invention provides a brightness adjustment device that does not require frequency accuracy in the initial duty ratio adjustment operation. That is, the present invention provides a first light-emitting device for changing the duty ratio of a pulse signal for driving control of a first light-emitting element for nighttime lighting by an external operation in an automobile display device composed of display members having different types of light-emitting elements. 1, the duty ratio of the pulse signal is once replaced with a level signal according to the duty ratio, and the duty ratio of the pulse signal for driving control of the second light emitting element for constant lighting is changed according to the level signal. The second change
and a detection output unit that detects whether or not the first light emitting element is lit and issues a signal that causes the second light emitting element to be lit at a predetermined brightness only when the first light emitting element is turned off. This is a characteristic feature.

(Function) Therefore, during the daytime when the first light-emitting element for lighting at night, for example, the instrument panel illumination lamp, is off, the second light-emitting element, for example, FLT, which is always on, is turned on by the signal from the detection output section. When lighting the instrument panel lighting lamp at night, the supply current for lighting is used as an oscillation pulse signal,
The illumination lamp blinks at a brightness speed that cannot be perceived by the human eye, and the brightness of the illumination lamp is adjusted by adjusting the duty ratio of the oscillation pulse signal. When the instrument panel illumination lamp for night lighting is turned on and adjusted to the desired brightness,
The oscillation panel signal is once converted to a level corresponding to the duty ratio, and the duty ratio of a drive control pulse signal that determines the luminance of the second light emitting element that is constantly lit is determined by the level signal. It is something. Therefore, the second light emitting element (for display), which is always on, lights up at a predetermined brightness during the day, and when the first light emitting element (for illumination) is turned on at night, the brightness of the first light emitting element changes. The brightness of the second light emitting element is also automatically adjusted by the adjustment.

(Example) Next, an example of the present invention will be described based on the drawings.

FIG. 1 shows an example of the circuit of the device of the present invention, and FIG. 2 shows voltage waveforms at appropriate circuit locations.

The device of the present invention is an illumination lamp group 1 (first light emitting element).
It consists of an illumination controller 2, a level signal conversion section 3, a triangular wave generation section 4, a comparison section 5, an output section 6, a detection output section 7, and a drive display section 8 (second light emitting element). Illumination lamp group 1 includes lamps 11 and 1 whose ends are connected via a power source 01 and a light switch 02.
2 and 13, the other end of lamp 11 is directly grounded, and lights up when light switch 02 is turned on, and does not require brightness adjustment. Lamps 12 and 13 require brightness adjustment, and are as follows: It is connected to the collector of the switching transistor (NPN type) 21 of the illumination controller 2 described in . The illumination controller 2 includes an oscillation circuit 23 equipped with a rheostat 22 that changes the duty ratio and the switching transistor 21.
The base of the switching transistor 21 is connected to the oscillation circuit 23, and the emitter is grounded. The level signal converter 3 includes a diode 31, a power supply 32, a capacitor 33, and a resistor 3.
A diode 31 is connected to the input line connected to the collector of the switching transistor 21 of the illumination controller 2 so that the input direction is the forward direction, and a power supply 32 and a resistor 34 are connected to the anode side of the diode 31. are connected in parallel, and the other end of the resistor 34 is connected to the input side of a capacitor 33 and an amplifier 35 whose other ends are grounded,
The output of the amplifier 35 is used as the output of the level signal converter 3. The triangular wave generating section 4 is a known one, and includes a rectangular pulse generating circuit in which a constant voltage is applied to the positive input side of a comparator 41, and a resistor 42 connected to the power supply side and a grounded capacitor 43 are connected in parallel to the negative input side. The rectangular pulse is used as a negative input of the comparator 44, a predetermined voltage is used as a positive input, and the comparator 4
Connect the capacitor 4 between the output side of 4 and the negative input.
5 and a resistor 46 in parallel. The comparator 5 has the output line from the level signal converter 3 connected to the minus input side of the comparator 51, and the output line from the triangular wave generator 4 to the plus input side. The output is the output of the comparator 5. The output section 6 is for amplifying the output of the comparison section 5 to a required potential. Also, the detection output section 7 is a transistor 7
1 is connected to the output side of the light switch 02 via a Tsuyuna diode (the side opposite to the base is in the forward direction) 72, the emitter is grounded, and the collector is connected to a predetermined power supply 73 and the anode of the diode 74. The cathode 74 is connected to the output line of the output section 6, and is connected to the drive section 8 from this connection point. The drive display section 8
It consists of a so-called driver such as an FLT drive IC or an LED drive circuit, and a display light emitting element (LED, FLT, EL, etc.) that displays engine speed and other information.

Next, the operation of the circuit example will be explained.

To illuminate the instrument panel at night, the light switch 02 is turned on, and the switching transistor 21 is turned on and off by the pulse signal of the oscillation circuit 23.
When activated, the potential waveform of the collector connection line (position A') of the switching transistor 21 is as shown in the _a1 wave in FIG. 2, and the lamps 12 and 13 are lit when the _a1 waveform is high. In the level signal converter 3, the potential across the capacitor 33 is determined by the duty ratio of the _a1 waveform and is smoothed, so the output of the level signal converter 3 (position B) is Figure 2 b As per wave ₁ , a is the average value waveform of ₁ wave. Next, the output wave (position C) from the triangular wave generator 4 is as shown in wave c in FIG. Comparison part 5
inputs the b ₁ wave and the c wave, and when they are superimposed, the waveform shown in _FIG . In response to the output signal of the comparison section 5, the light emitting element of the drive display section 8 lights up when the _e1 wave in FIG. 2 is high. Next, adjust the rheostat 22 and start the oscillation circuit 2.
The duty ratio of the pulse signal of 3 is changed and the second
As shown in wave A'a ₂ in Figure A, when the lighting time of the lamps 12 and 13 is shortened to reduce the brightness of the lamps 12 and 13, the output of the level signal converter 3 becomes the second wave.
Figure b) There are _two waves, and the potential is slightly higher than _{the first} wave.
When this is superimposed with the triangular wave c, it becomes D' in Fig. 2, and the output from the comparator 5 becomes ₂ waves H'd in Fig. 2.
Furthermore, the time for which electricity is applied to the light emitting element is the high part of the _e2 wave, and the light is attenuated compared to the _e1 wave.

Furthermore, when the light switch 02 is turned off during the daytime, the transistor 71 of the detection output section 7 is turned off, and the potential of the power supply 73 is applied to the drive display section 8, so that the light emitting element is made to emit light, and the light switch 02 is turned off. When turned on, transistor 71
is turned on, the power supply 73 of the detection output section 7 is not applied to the drive display section 8, but the output signal from the output section 6, that is, the pulse signal of the adjusted duty ratio described above is applied.

Therefore, during the daytime, the display light emitting element in the instrument panel emits light at a predetermined brightness, and when the night light switch 02 is turned on, the instrument panel illumination turns on and is driven by a pulse signal with a predetermined duty ratio to dim the light. When the brightness of the instrument panel illumination is adjusted, the light emitting element for display also decreases or increases the brightness by a predetermined degree accordingly, resulting in a display with a brightness balance that is easy for the driver to see.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and the pulse signal of the duty ratio that is operated to adjust the brightness of the light emitting element lit at night is once replaced with a level signal, and the pulse signal can be used for constant display as well as during the day. The duty ratio of the pulse signal that drives the other types of light-emitting elements that are lit can be determined by the level signal, and the substitution with the level signal is also possible in addition to the above-mentioned embodiment in which the average value is directly converted into a signal. It may be replaced with an integral average value, an effective value, etc. Further, the mechanism for generating a pulse signal with a duty ratio corresponding to a level signal may be other than the combination of a stationary triangular wave and a level signal wave.

(Effects of the Invention) As described above, the present invention provides a driving control pulse signal for the light emitting elements that are lit at night in an automobile display device having many types of light emitting elements with different luminance duty ratio luminance characteristics. Other types of light emitting lights for display that change the duty ratio, adjust the brightness, and once replace the level signal with the pulse signal of the duty ratio, and are constantly lit with the pulse signal of the duty ratio corresponding to the level signal. By lighting up the elements, it is possible to balance the luminance between day and night luminescent displays, and to adjust the luminance of other types of light emitting elements, the transmission means is replaced with a level signal instead of a pulse signal that is directly adjusted. This has the advantage that frequency accuracy is not required for the pulse signal whose duty ratio is to be adjusted by direct manipulation.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 shows an example of a circuit, and FIG. 2 shows potential waveforms at appropriate locations. 01 is a power supply, 02 is a light, 1 is a group of illumination lamps, 11, 12, 13 are lamps, 2 is an illumination controller, 21 is a switching transistor, 2
2 is a rheostat, 23 is an oscillation circuit, 3 is a level signal converter, 31 is a diode, 32 is a power supply, 3
3 is a capacitor, 34 is a resistor, 35 is an amplifier, 4
is a triangular wave generator, 41 and 44 are comparators, and 42 and 4 are
6 is a resistor, 43 and 45 are capacitors, 5 is a comparison section, 51 is a comparator, 6 is an output section, 61 is an amplifier,
7 is a detection output section, 71 is a transistor, 72 is a Tsuyuna diode, 73 is a power supply, 74 is a diode, and 8 is a drive display section.

Claims (1)

[Claims] 1. In an automobile display device composed of display members having different types of light emitting elements, a first adjustment in which the duty ratio of a pulse signal for driving control of a first light emitting element turned on at night is changed by external operation. a mechanism for once replacing the duty ratio of the pulse signal with a level signal according to the duty ratio, and changing the duty ratio of the pulse signal for driving control of the constantly lit second light emitting element according to the level signal; 2, and a detection output unit that detects whether or not the first light emitting element is lit and issues a signal that causes the second light emitting element to be lit at a predetermined brightness only when the first light emitting element is turned off. A display brightness adjustment device in an automobile display device, characterized by: