JPH058488Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention is applicable to, for example, instruments installed on the panels of various equipment mounted on equipment such as ships and automobiles. An illuminated device comprising a configuration in which the surrounding area or the instrument and the vicinity of the instrument are illuminated, and the brightness of this illumination is variably controlled in accordance with the surrounding environment,
In particular, the present invention relates to an improvement in an illumination device in which the illumination brightness can be controlled extremely easily and finely adjusted even though it has a simple structure. In the present invention, illumination of an instrument is defined as, for example, when the indicator (or pointer, etc.) is illuminated with a light-emitting element (for example, an indicator lamp or light-emitting diode "LED"), or when the display itself is illuminated. This is a general term for cases where the lighting is composed of light-emitting elements (for example, display instruments consisting of digital alphanumeric displays, etc.), and "lighting around instruments" is defined as:
This is a general term used to refer to cases where an instrument (regardless of singular or plural) is included and the surrounding area related to the instrument (for example, an automobile instrument panel) is illuminated. Furthermore, the illumination of the "instruments" and the "periphery of the instruments," the illumination of the indicator and the display section, etc. will be referred to as the illumination of the "display section" below.

This will be explained below using the drawings.

<Prior Art> This type of illuminated device will be specifically described below, taking as an example an illuminated device for a controller or instruments installed on the bridge of a ship.

This lighted device has a structure that controls it according to the surrounding environment. That is, even in the daytime when sunlight hits the ship, the surroundings surrounding the bridge can be seen by the helmsman, so the illumination brightness of the display unit may be bright. On the other hand, at night, it is difficult to see the surroundings, so it is necessary to darken the display according to the surrounding environment to make it easier to understand the surrounding situation. This function that controls the illumination brightness of the display according to the surrounding environment is called a dimmer.

FIG. 3 is a block diagram showing the configuration of a conventional illumination device that employs this dimmer.

In Figure 3, VR ₁ and VR ₂ are variable resistors (not shown) that adjust the amount of current flowing to the display section, 1 is a digital output pulse width length control circuit that controls the length of the pulse width, and 2 is the pulse width. The output of the length control circuit 1 is guided to an ON/OFF signal that changes the ratio (duty) of the display section's on time and off time (where the pulse width is τ and the pulse repetition period is λ, the pulse repetition period is generally λ) The longest is
It is about 5msec. This is a pulse repetition period length/shortening control circuit that outputs a signal (when the pulse width τ becomes short, the flickering of the display becomes noticeable).

FIG. 4 is a waveform diagram showing the pulse repetition period τ. In this figure 4, L is "light" and D is "dark".
Figure a shows the case where the pulse repetition period τ is changed by changing the resistance value of variable resistor VR ₁ , and figure b shows the case where the pulse width τ is changed by changing the resistance value of variable resistor VR ₂ . It is a pulse waveform diagram.

Normally, one of these two methods is used to perform deimaging. However, if there are multiple objects to be daimered, and if they are controlled by sequentially switching them, and the display switching and pulse repetition period τ are asynchronous, each display lighting time will be ~ (1 to 3 This may result in unevenness as shown in (the second display area). To solve this problem, a synchronous circuit may be provided to make the pulse repetition frequency and display switching frequency the same, but using a synchronous circuit increases the number of parts and deteriorates reliability. In addition, there are problems with the layout of the entire circuit, which makes it impossible to miniaturize.

Therefore, as a method of solving this problem without using a synchronization circuit, it is possible to create the waveform diagram of the daima pulse shown in FIG. 4d. That is, by including a large number of pulses in each display of each display lighting time, the pulse width length/shortening control circuit is configured to reduce the magnitude of non-uniformity (variation) (make the non-uniformity less noticeable). 1.

<Problems to be solved by the invention> However, even in the case of Fig. 4 (d), the width and number of pulses must be confirmed by experiment.
In addition, difficult adjustments and delicate illuminance adjustments (adjustments due to variations in brightness when most of the display is LED) are required, and it is difficult to realize them. Even if this were to be realized, the burden on the software would be large. In addition, when using a device that uses a microprocessor, it is not possible to achieve only the illuminance adjustment function with a volume knob, and adjusting this with an on/off switch input inevitably requires a digital-to-analog conversion circuit, etc. , the cost is quite high. Moreover, the power supply capacity for display becomes large.

The present invention was devised in view of the problems of the conventional technology, and is a method for easily converting digital signals into analog signals, while reducing the size of equipment and the number of parts, and having high reliability. It is an object of the present invention to provide an illumination device configured to adjust the brightness of a display section by varying a constant current value from a constant current circuit using this analog signal.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the lighting device of the present invention that controls the illumination brightness of the display section according to the surrounding environment uses a light emitting element to illuminate the instrument or the vicinity of the instrument or the instrument and the instrument. In an illuminated device in which the periphery of a meter is illuminated and the brightness of this illumination can be changed, the input part is connected to an input part that outputs a lighting signal by instructing an increase or decrease in the brightness. a brightness control unit that determines the instruction content of the illumination signal and outputs a control signal; a switching element that includes a plurality of switches that each turn on and off in accordance with the control signal; and a plurality of switches that are connected in series to each of the plurality of switches. and a resistance element whose one end is connected to a predetermined voltage and whose other end is connected to a common connection portion of the plurality of resistance elements, and forms a resistance ratio division proportional to a signal change of the control signal. a voltage output section that obtains a voltage output with a value according to the resistance ratio division from the connection point α of the common connection part; The device is characterized by comprising a constant current circuit that flows through the element.

<Function> For this reason, the input section instructs the change in illumination brightness,
The brightness control section determines the instruction content from the input section and outputs a control signal to the voltage output section, and the voltage output section forms a resistance ratio division proportional to the control signal, and a value corresponding to this resistance ratio division. obtain a voltage output of
A constant current circuit is connected to the voltage output section and outputs a constant current proportional to the voltage output to the display section.

<Example> Hereinafter, an example of the present invention will be described in detail based on a block diagram of an illuminating device shown in FIG. 1, which is a specific example of the present invention.

In FIG. 1, reference numeral 3 denotes an input section that outputs a lighting signal L _S by instructing a change (increase/decrease) in the illumination brightness of the display section 8. In this example, an up switch 3a used to brighten the display section 8 is used. , and a down switch 3b used to darken the display section 8. 4 is composed of, for example, a microprocessor to which the input section 3 is connected, which determines the instruction content (state) of the illumination signal L _S (input value) at this time and outputs a control signal D _I as a code output. This is a brightness control section. This brightness control section 4 includes an up switch 3a
When the down switch 3b is ON, the value of the control signal _DI is increased, and when the down switch 3b is ON, the value of the control signal _DI is decreased. When incorporating L _S , an input port section may be provided externally to accommodate cases where it is caught in periodic scanning). 5
is a voltage output section which forms a resistance ratio division proportional to a signal change of the control signal D _I from the brightness control section 4 and obtains a voltage output having a value corresponding to this resistance ratio division. This voltage output section 5 includes a switching element 6 consisting of switches _SW1 to _SW8 , each of which turns on and off according to the value of the control signal _DI , and whose other ends are commonly connected and grounded.
The switching element 6 is composed of resistors R ₁ to R 8 which are commonly connected to one end of each of the switches SW ₁ to _{SW 8} , and whose other end is connected to +V _REF via _a resistor R ₀ in this example. Voltage output V _A corresponding to resistance ratio division proportional to signal change of control signal D _I of this voltage output section 5
is obtained from the connection point α between the resistors R ₁ to R ₈ and the resistor R ₀ . That is, the voltage output V _A is the resistance R ₀ and the switch
Ratio of the combined resistance value with the resistors R ₁ to _{R 8} connected to SW ₁ to SW ₈ when they are turned on (resistance ratio division)
and +V _REF . Now Switch SW ₁
~Combined resistance when all SW ₈ are turned on
When expressed as R ₁ /R ₂ /R ₄ /R ₈ , the voltage output V _A at that time
is V _A = {(R ₁ /R ₂ /R ₄ /R ₈ )/(R ₁ /R ₂ /R ₄ /R ₈ )+R ₀ }V _REF (1). 7 is connected to the voltage output section 5 and outputs the voltage.
This is a constant current circuit that outputs a constant current I _L having a value proportional to V _A to the display section 8 .

This constant current circuit 7 is composed of, for example, a light emitting diode, with an input resistor R _I connected to the base of the transistor Tr ₁ , a resistor R _L whose other end is grounded to its emitter, and a collector connected to the power supply V _h at the other end. A display section 8 consisting of light emitting elements H _{1 .} . . H _o is connected thereto. Now, assuming that the voltage between the base and emitter of transistor Tr ₁ is V _BE , the constant current I _L is I _L = (V _A − V _BE )/R _L (2). Here, since V _A >>V _BE , equation (2) is I _L ≒ {(R ₁ /R ₂ /R ₄ /R ₈ )/(R ₁ /R ₂ /R ₄ /R ₈ )+R ₀ }・V _REF /R _L …(3). That is, the value of the constant current I _L can be determined depending on the content of the combined specific resistance of the voltage output section 5.
If each resistance R ₁ , R ₂ , R ₄ , R ₈ is weighted (for example
R ₈ = 2R ₄ −4R ₂ = 8R ₁ ), it is possible to obtain a constant current that changes linearly in response to the control signal _DI .

FIG. 2 is a flow sheet showing the flow of these relationships.

<Effects of the invention> As described above in detail with the embodiments, the input section instructs the change in illumination brightness, and based on this instruction, the voltage output section changes the value according to the resistance ratio division. According to the illuminated device of the present invention, which has a configuration in which a voltage output is obtained and a constant current with a value proportional to the voltage output is output from a constant current circuit to a display section,: Separate time division circuits etc. for pulse width, frequency, etc. Since there is no need to provide one, the device can be made simple and compact, and can be manufactured at low cost.

: In principle, the structure is such that a light emitting element is provided in series with a constant voltage circuit, so there is no variation in the illuminance of the light emitting element (which is generally proportional to the current). or,
Flickering in illuminance due to power supply voltage fluctuations is reduced.

: Since the brightness control section only needs to output a brightness control signal which is a code output, the software of the brightness control section can be easily implemented. There are other effects.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an illuminated device which is a specific embodiment of the present invention, Fig. 2 is a flow sheet of Fig. 1, Fig. 3 is a block diagram of a conventional illuminated device, and Fig. 4 is a block diagram of an illumination device according to the present invention. It is a pulse repetition period waveform diagram. 3... Input section (up switch 3a, down switch 3b), 4... Brightness control section, 5... Voltage output section, 7... Constant current circuit, 8... Display section.

Claims (1)

[Scope of utility model registration request] In an illuminated device in which a meter or the vicinity of the meter, or a meter and the vicinity of the meter are illuminated with a light-emitting element, and the brightness of this illumination can be changed, an input that outputs a lighting signal by instructing an increase or decrease in the brightness. 3, a brightness control section 4 to which the input section is connected to determine the instruction content of the illumination signal and output a control signal, and a switching element comprising a plurality of switches, each of which is turned on and off according to the control signal; It consists of a plurality of resistance elements connected in series to each of the plurality of switches, and a resistance element whose one end is connected to a predetermined voltage and the other end is connected to a common connection part of the plurality of resistance elements, and the signal of the control signal. a voltage output section 5 that forms a resistance ratio division proportional to the change and obtains a voltage output of a value corresponding to the resistance ratio division from the connection point α of the common connection part; 1. A lighting device comprising: a constant current circuit 7 which obtains a constant current value proportional to , and supplies the constant current value to the light emitting element.