JPH046075Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement of a display device that displays the magnitude of the output level of an amplifier using a light emitting diode (hereinafter abbreviated as LED).

[Conventional technology] A large number of LEDs are arranged side by side as a level meter for an amplifier, and the number of LEDs is set according to the output signal level.
There is a display device in which an LED lights up and the length of the lit part visually changes depending on the signal level.The lighting circuit for lighting up many LEDs of the same color in this way is shown in Figure 2a. There is a configuration in which a plurality of series circuits of LEDs and resistors R are connected in parallel, as shown in FIG. 2, or a configuration in which a plurality of LEDs and resistors R are all connected in series as shown in FIG. 2B.

[Problem to be solved by the invention] In such conventional examples, in general, individual LEDs
Brightness and color may vary due to differences in performance.
In the circuit shown in Figure 2b, the brightness of the LEDs cannot be adjusted individually, which often makes the display device unsightly.In the circuit shown in Figure 2a, the current value can be changed by individually adjusting the resistor connected to each LED. Although it is possible to keep the brightness constant, it has the disadvantage that the color cannot be adjusted. In particular, when yellow or orange LEDs, which have large color irregularities, are used, this drawback is usually noticeable.

In order to eliminate this drawback, an improved structure was developed in which red and green light-emitting diodes were integrated into one unit, and current was passed through each diode through a variable resistor to individually distribute the current. There is a display device (not shown) that can be set to adjust the color (chromaticity) of the composite color.

[Problems to be solved by the invention] In the conventional example described above, even if the display device has the latter improved structure, both the chromaticity and the luminance are controlled by the two variable resistors for adjusting the chromaticity. Since the diodes fluctuate simultaneously, there is a problem in that when a large number of diodes are arranged and used, it takes a lot of effort to make the chromaticity and luminance of all the diodes match.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit for a display device that eliminates the drawbacks of the above-mentioned conventional examples by making it possible to adjust chromaticity and brightness independently.

[Means for Solving the Problems] The configuration of the circuit for a display device according to the present invention is as shown in FIG. 1 showing the configuration of an embodiment. (i
= 1, 2, ..., i) red terminal r is variable resistor Vri
(i = 1, 2, ..., i), and the green terminal g of the LED 1i is connected to the other terminal of the variable resistor Vri, and the variable resistor
The slider terminal of Vri is the variable current source Vi(i
= 1, 2, . . . , i) are connected to a common power source E in parallel. .

[Function] In the above configuration, the chromaticity of the LED1i is determined by setting the position of the slider terminal of the variable resistor Vri connected to each LED to uniquely set the current distribution of the red and green diodes. is determined. or,
When adjusting the brightness, simply adjust the current flowing from the variable current source Vi connected to each LED1i, and you can adjust only the brightness without changing the current distribution of the red and green diodes that have been set. Can be adjusted freely independently.

[Example] The circuit configuration of an embodiment of the present invention is shown in FIG.

In the figure, 11, ..., 1i are LEDs with two colors, red and green, and the red terminal r variable resistor of the LED 1i
To one terminal of Vri (i=1,2,...,i),
Further, the green terminal g of the LED1i is connected to the other terminal of the variable resistor Vri, and the variable resistor
The slider terminal of Vri is the variable current source Vi(i
= 1, 2, ..., i), and one composite light emitter unit circuit Ci (i = 1, 2, ..., i)
The required number (i) of such unit circuits Ci are connected in parallel to a common power source E. Brightness adjustment is performed for each unit circuit Ci by adjusting the variable current source Vi, and chromaticity adjustment is similarly performed by changing the current distribution of the red and green light emitting diodes for each unit circuit Ci using the respective variable resistors Vri. conduct.

Examples of the configuration of the variable current source Vi described above are shown in FIGS. 3a, b, and c. Figure 3a shows the variable current source V
In this method, a fixed bias V _B is applied to the transistor i, and the current is changed by varying the emitter resistance VR _MA . In Fig. 3b, a depletion mode FET is used in place of the transistor in Fig. 3a. This is a circuit with zero bias. Further, FIG. 3c shows a configuration in which the current value is simply adjusted by a variable resistor _VRMC , and has the feature of a simple structure with a small number of parts.

[Effect] The display device circuit of the present invention has two colors, red and green.
Since the brightness and chromaticity of the composite color can be adjusted separately and independently using LEDs, it is extremely easy to match the brightness and color when a large number of LEDs are used together, and it is also possible to adjust the color Since it can produce red, green, and any intermediate color between them, it has an extremely wide chromaticity range, and is the most practical and excellent circuit for display devices.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of the circuit for a display device of the present invention, Figures 2a and b are circuit diagrams of two conventional examples, and Figures 3a, b, and c are three examples of variable current sources. It is a circuit diagram. 1i (i=1, 2, . . . , i) is a light emitting diode (LED).

Claims (1)

[Scope of utility model registration request] The red terminal r of the red and green two-color light emitting diode (hereinafter abbreviated as LED) 1i is connected to one terminal of the variable resistor Vri, and the green terminal g of the LED 1i is connected to the variable resistor.
A plurality of unit circuits Ci are connected in parallel to a common power source E, each of which is connected to the other terminal of Vri, and whose slider terminal of the variable resistor Vri is connected to a variable current source Vi. A circuit for a display device.