JPH0230925Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a channel display circuit device for a television receiver, and more particularly to a channel display circuit device using display elements such as LEDs (light emitting diodes).

<Prior art> Conventionally, in television channel displays using display elements such as LEDs, the brighter the display, the easier it is to see, but in normal times when there is no need to look at the channel display, it is more difficult to see the screen. However, there was a problem that the channel display was obtrusive. This tendency is particularly noticeable with red LEDs, which are widely used because they are inexpensive.

<Purpose of the invention> The present invention has been made in view of the above points, and eliminates the above-mentioned disadvantages by changing the brightness of the channel display when selecting a channel and during normal times other than when selecting a channel. The purpose is to remove.

<Configuration of the invention> In order to achieve the above-mentioned object, the present invention includes a muting signal generation circuit that forms and outputs a muting signal for muting tuning noise in response to a tuning operation, and an applied drive voltage a display element that displays the selected channel at a brightness corresponding to the level of the display element, a drive circuit that applies a drive voltage to the display element to drive the display element, and a drive voltage supply source and the drive circuit. A switching circuit is connected to the switching circuit to form the drive voltage at a level corresponding to the presence or absence of the muting signal from the muting signal generation circuit and supply it to the drive circuit.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The drawing is a circuit diagram of an embodiment of the present invention. In the figure, 1 is a muting signal generation circuit that forms and outputs a muting signal S1 for muting channel selection noise in response to a channel selection operation, and 2 is a muting signal generation circuit that selects a brightness according to the level of the applied drive voltage. LED as a display element that displays the station channel, 3 is a drive circuit that applies a drive voltage to LED 2 to drive the display, 4 corresponds to the 10th digit and 1st digit of the channel, respectively.
Each segment 2 of LED 2 arranged in a Japanese-shape
A selection circuit 5 is connected between the drive voltage supply source 6 and the drive circuit 3 and outputs a selection signal S2 for selecting a, 2b, . . . This is a switching circuit that forms drive voltages of levels corresponding to the respective levels and supplies them to the drive circuit 3.

The drive circuit 3 controls the 10th digit and 1st digit of LED2.
A drive signal output circuit 7 that outputs drive signals S3, S4 for driving the LED segments 2a, 2b, . . . , a transistor Q3 whose base is driven by the drive signals S3, S4 from the drive signal output circuit 7, Including Q4. In this example,
LED2 is driven by a dynamic drive method. The switching circuit 5 consists of transistors Q1, Q2 and voltage dividing resistors R1, R2. The base of the transistor Q1 is driven by the muting signal S1 from the mutating signal generating circuit 1, and the transistor Q2 has a series voltage dividing resistor R1, R2.
base drive from the connection point. A channel selection IC 8 includes a muting signal generation circuit 1, a drive signal output circuit 7, and a selection circuit 4.
Note that R3 to Rn are current limiting resistors.

Next, the operation of the channel display circuit device having the above configuration will be explained. First, in normal times other than when selecting a channel, the muting signal S1 is in a high level state, that is, in this embodiment, there is no muting signal S1, and at this time, the transistor Q1 of the switching circuit 5 is conductive. The voltage Ea at the connection point A is 12V when the voltage of the drive voltage supply source 6 is 12V.
Therefore, if R1=R2, Ea=6V. Therefore, the emitter voltage of transistor Q2 is approximately 5.4V, and LED2 is driven at approximately 5.4V.

Next, when selecting a channel, the muting signal S
1 is at a low level, that is, in this embodiment, the muting signal S1 is present, and at this time, the transistor Q1 of the switching circuit 5 is cut off, and 12V is applied to the base of the transistor Q2. Therefore, transistor Q2
The emitter voltage of is approximately 11.4V, and LED2 is approximately
It will be powered by 11.4V. In this way, the present invention responds to the presence or absence of a muting signal, and uses approximately twice the normal drive voltage when selecting a channel.
Since it drives LED2, it lights up with sufficient brightness when selecting a channel, while it dims during normal times, so it does not interfere with viewing the screen, and furthermore, the lifespan of LED2 is improved.

In addition, in order to change the ratio of the brightness of LED 2 between when selecting a channel and during normal operation, use the voltage dividing resistor R of the switching circuit 5.
1. Just change the ratio of the resistances of R2.

In the above-mentioned embodiment, the LED 2 was configured to turn on brightly only when a channel is selected, but in another embodiment of the present invention, an integral circuit may be used to keep the LED 2 bright for a while after the channel selection is completed. It may be configured so that it lights up.

<Effects of the invention> As described above, according to the invention, there is provided a muting signal generation circuit that forms and outputs a muting signal for muting tuning noise in response to a tuning operation, and a muting signal generation circuit that generates and outputs a muting signal for muting tuning noise in response to a tuning operation, and a display element that displays a selected channel at a corresponding brightness; a drive circuit that applies a drive voltage to the display element to drive the display element; and a drive circuit that is connected between a drive voltage supply source and the drive circuit. A switching circuit is provided to form the drive voltage at a level corresponding to the presence or absence of the muting signal from the muting signal generation circuit and supply it to the drive circuit, so that a bright channel display is provided when selecting a channel. It is easy to see, and by darkening the channel display during normal times other than when selecting a channel, it does not become an eyesore when viewing the screen as in the past. moreover,
Under normal conditions, the drive voltage is low, so the LED
It becomes possible to extend the life of display elements such as.

[Brief explanation of drawings]

The drawing is a circuit diagram of an embodiment of the present invention. 1... Muting signal generation circuit, 2...
LED, 3...drive circuit, 5...switching circuit.

Claims (1)

[Claims for Utility Model Registration] A muting signal generation circuit that forms and outputs a muting signal for muting tuning noise in response to a tuning operation, and a muting signal generation circuit that generates and outputs a muting signal that mutates tuning noise in response to a tuning operation, and a muting signal generation circuit that generates a muting signal that mutates tuning noise in response to a tuning operation, and a muting signal generation circuit that generates a muting signal that mutates tuning noise in response to a tuning operation. a display element that displays a local channel; a drive circuit that applies a drive voltage to the display element to drive the display element; and a muting signal generation circuit that is connected between a drive voltage supply source and the drive circuit. A channel display circuit device comprising: a switching circuit that forms the drive voltage at a level corresponding to the presence or absence of a muting signal from the drive circuit and supplies the drive voltage to the drive circuit.