JPS62466B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an easy-to-understand display of the volume adjustment status when the volume is adjusted using a D-A conversion circuit using a pulse width conversion method in a television receiver or the like. The purpose is to provide a device that can do this.

Recently, a system has been developed that uses a microcomputer to control the various adjustment states of a television receiver, and for volume control, a voltage-controlled variable gain amplifier is used to control the volume. The voltage is generated digitally and is generated by D/A conversion. In addition, one microcomputer chip
When configured using an IC or the like, in order to reduce the number of pins, the control voltage is generated by a digital signal that is pulse-width-converted, smoothed, and applied to a variable gain amplifier. However,
If signals and voltages for volume control are generated as digital signals in this way, it is no longer possible to use a display means that displays the volume adjustment status using a variable resistor knob as in conventional devices. A new problem has arisen in that it is difficult to understand how much the volume has been adjusted.

SUMMARY OF THE INVENTION In view of this, an object of the present invention is to provide a device that can display the volume adjustment status in an easy-to-understand manner even when the volume is adjusted using a D-A conversion circuit using a pulse width conversion method. It is something.

Therefore, in the present invention, different gate pulses are generated according to each of the control pulses with a plurality of duty ratios for volume control, and the gate pulses are added to a gate circuit to gate the control pulses. and selectively generates an output that detects the duty ratio of the control pulse, and uses this output to selectively light a plurality of indicator lights to display the volume adjustment status. It is.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing its configuration, and FIG. 2 is a waveform diagram showing waveforms at each part thereof. Here, we will show a case where the volume is adjusted in 16 levels.

First, in FIG. 1, 1 is an audio detection circuit, 2
3 is a voltage-controlled variable gain control circuit, 3 is an output amplification circuit, and 4 is a speaker, which are similar to those of a normal television receiver. on the other hand,
Reference numeral 5 denotes a control voltage generation circuit using a pulse width conversion type D-A conversion circuit that generates a volume control voltage for volume adjustment, and a clock generation circuit 6 that generates a basic clock signal, and a control voltage generation circuit that uses a pulse width conversion type D-A conversion circuit to generate a volume control voltage for volume adjustment. A volume control circuit 7, such as a remote control receiving circuit, which issues commands, and a pulse width conversion circuit 8, which selectively generates a plurality of types of volume control pulses whose duty ratios are varied according to the volume adjustment value, in accordance with the commands. and a smoothing circuit 9 for smoothing this control pulse and applying it to the variable gain amplifier circuit 2 as a volume control voltage.

The volume control circuit 7 normally issues a command signal in the form of a digital signal, and here, since the adjustment is in 16 stages, a 4-bit binary command signal is issued. The pulse width conversion circuit 8, for example, divides the frequency of the clock signal and generates a start pulse at a cycle of 16 times, and after the start pulse, generates an end pulse separately for each clock signal. A frequency dividing circuit, a flip-flop which is set by the start pulse and reset by the end pulse to generate a volume control pulse, and which end pulse is applied to this flip-flop is determined by a command signal from the volume control circuit 7. It is composed of a decoder, a gate group, etc., which selects the pulse width of the control pulse, that is, the duty ratio, depending on the selection. Therefore, the control pulses generated from this pulse width conversion circuit 8 have the same leading edge position and change in trailing edge position in 16 steps (including pulse width 0) as shown in FIG. 2 A to P. It is a pulse signal whose duty ratio changes in 16 steps such as 1/16, 2/16, 15/16, and 16/16. For example, the higher the duty ratio, the louder the volume. These A in response to commands from circuit 7
~P is selected and generated.
Therefore, if the control pulses selectively generated by the smoothing circuit 9 are smoothed and averaged by a low-pass filter,
It is possible to obtain 16 levels of analog control voltage, and by adding this to the variable gain amplifier circuit 2, the volume can be adjusted in 16 levels.
Note that 10 is a muting circuit that generates a low-level muting pulse for muting audio when selecting a channel or the like.

Next, the display circuit 11, which is a feature of this device, will be explained. This part consists of a gate pulse generation circuit 12 that generates a plurality of gate pulses for detecting which of the control pulses shown in FIG. a plurality of gate circuits 13a that gate control pulses and selectively generate detection outputs;
13p and a plurality of indicator lights 14a to 14p provided on the output side of each gate circuit 13a to 13p so as to be turned on by the output thereof. The gate pulse generation circuit 12 takes out the above-mentioned start pulse and end pulse from the pulse width conversion circuit 8, or resets the frequency dividing circuit with the signal from the pulse width conversion circuit 8 and generates the clock signal from the clock generation circuit 6. By dividing the frequency or the like, 16 gate pulses are generated at different positions corresponding to each of the volume control pulses A to P in synchronization with the clock signal, as shown in FIGS. 2a to 2p. Here, since the trailing edge of the control pulses A to P is changed,
Each of the gate pulses a to p is generated at the position of one bit on the trailing edge of each of the control pulses a to p.

Each of the gate pulses a to p is added to the gate circuits 13a to 13p, respectively, and the control pulse and muting pulse are added to the gate circuit 13a to 13p, respectively.
Commonly added to 3a to 13p.

With this configuration, when the volume control circuit 7 generates a command signal to adjust the volume, and the pulse width conversion circuit 8 generates a control pulse with a corresponding duty ratio to adjust the volume, the gate Of the circuits 13a to 13p, only those to which the gate pulse that exists within the pulse period of the control pulse is applied conducts and generates an output, and the number of indicator lights 14a to 14p corresponding to the volume adjustment at that time is turned on. The volume adjustment status can be displayed based on the number of lit lights. For example, if the volume is adjusted to the fourth level and a control pulse as shown in FIG. 2D is generated, gate circuits 13a, 1
The four indicator lights 3b, 13c, and 13d are electrically connected, and the four indicator lights 14a, 14b, 14c, and 14d are lit.

Similarly, all the indicator lights 13a to 13p do not light up when the volume is adjusted to the minimum level by the control pulse A, and the indicator lights 13a and 13b are subsequently turned on as the adjustment state changes to increase the volume one step at a time. ，
13c, . . . 13p light up while increasing by one.

Therefore, the user can immediately know the adjustment status of the volume by looking at the lighting status of the indicator lights 13a to 13p, and the adjustment status is displayed in an extremely easy-to-understand manner.

Note that when the audio is being muted by the muting circuit 10, the volume is at the minimum regardless of the volume adjustment state, so if only the above-mentioned display is displayed, the user may misunderstand that there is a malfunction. Therefore, as shown in FIG. 1, gate circuits 15a to 15p and indicator lights 16a to 16p are further provided.
If a control pulse and a gate pulse are applied to a to 15p, and the muting pulse from the muting circuit 10 is inverted and applied by the inverter 17, the mutating circuit 1
When a low-level mutating pulse is generated from 0 to a muting state, the gate circuits 13a to 13p are cut off and instead the gate circuits 15a to 15p are made conductive according to the adjustment state at that time, and the indicator lights 16a to 16p are turned on. 16p can be used for display. If the display colors of the indicator lights 14a to 14p and the display colors of the indicator lights 16a to 16p are made different, the user can be clearly informed of the muting state, eliminating anxiety about malfunctions. Usability can be improved. The indicator lights 16a to 16a also indicate how loud the volume will be when the muting state is released.
Since it can be displayed in 16p, it can be useful for changing the adjustment of the question.

Of course, if there is no need to display the adjustment state during the muting state, the output of the inverter 17 may be used to directly display one indicator light. Furthermore, without applying a muting pulse to the gates 13a to 13p,
13p is kept operating, and the indicator lights 13a to 13 are turned on with the muting pulse when in the muting state.
It is also possible to light up an indicator light of a different color from p.

As is clear from the explanation of the above embodiments,
In the present invention, in a device that adjusts the volume using a pulse width conversion type D-A conversion circuit, the volume control pulse whose pulse width has been converted is gated with gate pulses at different positions, and its duty ratio is detected. However, since the indicator light is turned on by the detection output, it is possible to obtain a device that can display the adjustment state of the volume in an extremely easy-to-understand manner.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a volume display device according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part of the device. 2... Variable gain amplifier circuit, 5... Control voltage generation circuit, 6... Clock generation circuit, 7... Volume control circuit, 8... Pulse width conversion circuit, 9... Smoothing circuit, 10... Muting circuit, 11...Display circuit, 12...Gate pulse generation circuit, 13a~
13p...Gate circuit, 14a-14p...Indicator light, 15a-15p...Gate circuit, 16a-1
6p... Indicator light, 17... Inverter.

Claims (1)

[Claims] 1. A voltage-controlled variable gain amplifier circuit that amplifies an audio signal, a clock generation circuit that generates a clock signal, and a duty ratio that is synchronized with the clock signal and changes in accordance with a volume adjustment value. It is equipped with a pulse width conversion circuit that generates a plurality of types of volume control pulses, and a smoothing circuit that smooths the volume control pulse and applies it as a volume control voltage to the voltage-controlled variable gain amplifier circuit, and is synchronized with the clock signal. a gate pulse generation circuit that generates a plurality of gate pulses at different positions corresponding to each of the plurality of types of volume control pulses; A plurality of gate circuits gate volume control pulses to selectively generate output, and a plurality of indicator lights provided on the output side of each of the plurality of gate circuits and lit by the output. A volume display device characterized in that the plurality of indicator lights are selectively turned on according to the duty ratio of the volume control pulse to display the volume. 2. A patent claim further comprising a muting circuit that generates a muting pulse for mutating audio, and the muting pulse lights up an indicator light that is separate from the indicator light for displaying the volume. The volume display device according to scope 1. 3 A plurality of gate circuits to which a plurality of gate pulses are respectively applied and a volume control pulse and a muting pulse are commonly applied; A plurality of indicator lights that are lit are separately provided, and during the period when the muting pulse is generated, the separate indicator lights are selectively lit according to the duty ratio of the volume control pulse, and when the muting is released. 3. The volume display device according to claim 2, wherein the volume display device displays a volume.