JPH0442464A - Automatic recording level setting circuit for acoustic equipment - Google Patents

Abstract

PURPOSE:To perform the control of setting position of a volume for recording level setting with simple constitution and with high accuracy by detecting the setting position by the volume for recording level setting itself which performs the level adjustment of a recording signal. CONSTITUTION:The recording signal from a CD player inputted to a signal input terminal 1 according to peak search is supplied to a level display circuit 7 by a switch circuit 3, and also, a recording reference signal from a recording reference signal generation circuit 4 is supplied to a window comparator 18 via the volume 2 for recording level setting. The setting of a reference voltage based on level detection at the level display circuit 7 is performed at a peak holding circuit 9, and a reference voltage is compared with the recording reference signal at the window comparator 18, and the setting position of the volume 2 for recording level setting for a recording signal level is detected, and it is controlled to the setting position corresponding to the recording signal level. Thereby, the control of the volume 2 for recording level setting can be performed with simple constitution and with high accuracy corresponding to the level of an inputted recording signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic recording level setting circuit for audio equipment.

Traditionally, for example, in a tape recorder equipped with a compact disc (hereinafter referred to as "CD") player, the level of the recording signal input from the CD player is adjusted using the recording level setting volume before recording. By supplying the signal to the circuit, the recording signal from the CD player is recorded at the optimum level. In such a tape recorder, the setting position of the recording level setting volume is adjusted according to the level of the recording signal input from the CD player so that the setting position of the recording level setting volume is in the optimal level setting state. An automatic recording level setting circuit was provided to automatically control the position.

However, in the automatic recording level setting circuit of such a tape recorder, in order to detect the setting position of the recording level setting volume, a position detection volume that is linked to the recording level setting volume is used. is separately provided, and the position detection volume is used to detect the setting position of the recording level setting volume. Therefore, the conventional automatic recording level setting circuit requires an additional interlocking position detection volume, which increases the number of separate parts and complicates the configuration, resulting in increased costs. Furthermore, in such a conventional configuration, accuracy deteriorates due to mutual errors in the volume curves (variable resistance characteristics) of the recording level setting volume and the position detection volume, which are in an interlocking relationship.

The present invention has been made in view of these points, and is designed to accurately control the setting position of a recording level setting volume with a simple configuration according to the level of an input recording signal. The purpose of this invention is to provide an automatic recording level setting circuit.

In order to achieve the above-mentioned object of "1", the present invention provides an audio equipment in which a recording signal input during recording is once level-adjusted with a recording level setting volume and then supplied to a recording circuit. Level detection means for detecting the level of a recording signal supplied without going through the recording level setting volume during level setting to control the setting position of the recording level setting volume; and a standard for generating a recording reference signal of a predetermined level. A signal generating means compares the level of the recording reference signal from the reference signal generating means supplied via the recording level setting volume with the level of the recording signal detected by the level detecting means to determine the recording level. a position detection means for detecting the setting position of the setting volume; and a control means for controlling the recording level setting volume to a setting position corresponding to the level of the input recording signal based on the detection result of the position detection means. The configuration is as follows.

Fraud 1- According to such a configuration, the setting position is detected by the recording level setting volume itself that adjusts the level of the recording signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a tape recorder equipped with a CD player will be described as an embodiment of the present invention with reference to the drawings.

In Figure 1, (1) is the signal input terminal on the tape recorder side to which the right channel recording signal is input from the CD player during CD recording, and (2) is the signal input terminal on the tape recorder side when recording the recording signal from the CD player to the tape recorder. A recording level setting volume (in this case, a rotary electric volume rotated by a motor) adjusts the level of the recording signal from the signal input terminal (1), and (3) is a recording level setting volume (2). The switch circuit (4) switches from the contact A side to the contact B side in response to the supply of operating voltage when setting the level, which controls the level setting.The switch circuit (4) switches from the contact A side to the contact B side when the level is set. A reference signal generation circuit that outputs a high frequency recording reference signal,
(5) is a low-pass filter that prevents the recording reference signal from the reference signal generation circuit (4) from being supplied to the recording circuit side (the recording amplifier circuit, level display circuit, etc. described later) and allows only the recording signal to pass; 6) is a recording amplifier circuit that amplifies the recording signal from the low-pass filter (5) and outputs it to the recording head side; (7) is a level display circuit that detects the level of the recording signal and displays the level. As the recording signal increases, the level display circuit (7) sequentially outputs H level from the left side of the output terminals (7a) to (7g), and displays the display light emitting diodes (8a) to (8g). The lights are turned on sequentially from the left side.

(9) is a peak hold circuit that receives an operating voltage when setting the level and enters the operating state to hold the reference voltage of the window comparator, which will be described later.The peak hold circuit (9) is connected to the level display circuit (9) when the recording signal level is +3 dB. When an H level is output from the output terminal (7f) of 7), the silicon controlled rectifier (hereinafter referred to as rSCR) (1
0) turns on and holds the reference voltage determined by the voltage dividing resistors (11) and (12), and when the recording signal level is +6 dB and the read level is output from the output terminals (7f) (7g), SCR (10 ) (13) will turn on and hold the reference voltage determined by the voltage dividing resistors (11), (12), and (14). And (1
5) is a bypass filter that passes only the recording reference signal from the reference signal generation means supplied via the recording level setting volume (2), and (16) amplifies the recording reference signal that has passed through the bypass filter (15). amplifier circuit,
(17) is a rectifier circuit that rectifies and smoothes the recording reference signal from the amplifier circuit (16), and (18) is a rectifier that converts the rectified and smoothed output from the rectifier circuit (17) and the reference voltage held by the peak hold circuit (9). A window comparator that compares and detects the setting position of the recording level setting volume (2).
The window comparator (18) is connected to the first. Consisting of a second comparator (19) (20), the reference voltage held by the peak hold circuit (9) is passed through the voltage dividing resistor (21) in the window comparator (18) as the second reference voltage Vref to the second comparator. (20) is input to the inverting input terminal of the resistor (22), and the second reference voltage Vref is input to the inverting input terminal of the resistor (22).
) to the non-inverting input terminal of the first comparator (19) as the first reference voltage Vref'. Therefore, as shown in FIG. 2, if the rectified and smoothed output from the rectifier circuit (17) is smaller than the first reference voltage Vref', the window comparator (18) detects that the level setting by the recording level setting volume (2) is too small. The first comparator (19) outputs an H level UP signal to raise the setting position of the recording level setting volume (2), and if the rectified and smoothed output is greater than the second reference voltage Vref, the recording level setting volume If the level setting by the volume (2) is too high, the second comparator (20) sets the recording level setting volume (2).
) is designed to output an H level DOWN signal to lower the set position. Also, the rectified and smoothed output is the first
．． When the voltage falls between the second reference voltage νref" and Vref (within the window), it is assumed that the level setting by the recording level setting volume (2) is in an optimal state, and the outputs of the first and second comparators (19) and (20) go low. to the level, i.e. U
Neither the P nor DOWN signals are output. The input/output characteristics of the window comparator (18) change depending on the reference voltage held by the peak hold circuit (9). For example, if the level of the recording signal is low and is not held by the peak hold circuit (9), that is, the The voltage is connected to the voltage dividing resistor (21) in the window comparator (18).
(22) If determined by (23), the first. By increasing the second reference voltage VrefVrer', the output range of the UP signal is expanded. (24) is a motor drive I that receives the UP or DOWN signal from the window comparator (18) and drives the motor (25) for changing the setting position of the recording level setting volume (2) in forward and reverse rotation.
C.

(26) is a power supply control circuit that supplies operating voltage to the reference signal generation circuit (4), switch circuit (3), peak hold circuit (9), window comparator (1B), and motor drive 1c (24) during level setting. For example, when a peak search (CD peak level detection) is started in a CD player, an H level SET signal is input to the control terminal (27), and the power supply transistor (29) is input via the inverter (28). is turned on and starts supplying operating voltage.

Therefore, when setting the level on the tape recorder side in conjunction with the start of peak search in the CD player before CD recording, the recording signal from the CD player input to the signal input terminal (1) in conjunction with the peak search is switched. The circuit (3) supplies the signal to the level display circuit (7) without going through the recording level setting volume (2), and also supplies it to the recording reference signal generation circuit (
The recording reference signal from 4) is supplied to the window comparator (18) via the recording level setting volume (2). Then, the reference voltage is set in the peak hold circuit (9) based on the level detection by the level display circuit (7), and the reference voltage (i.e., the first and second reference voltages) and the recording reference signal (i.e., Rectified and smoothed output) is compared with the wind comparator (18) to adjust the recording level setting volume (2) for the recording signal level.
The setting position is detected, and based on the detection result, the motor driving IC (24) and motor (25) are controlled to the setting position corresponding to the recording signal level.

When recording a CD after setting the level, the recording signal from the CD player input to the signal input terminal (1) is sent to the level display circuit (3) via the recording level setting volume (2) by the switch circuit (3). 7), it will be supplied to the recording amplifier circuit (6), etc., and the recording signal will be recorded after being adjusted to an appropriate level by the recording level setting volume (2).

In this embodiment, the reference voltage is held at two types, +3 dB and +6 dB, by the peak hold circuit.
By further finely detecting the level every 3 dB, the setting position of the volume for setting the recording level may be controlled more finely.

Further, in this embodiment, the SET signal is input when the peak search of the CD player is started, but the present invention is not limited to this. Furthermore, in this embodiment, only the right channel system was explained, but the left channel system is the same, and the output from the level display circuit on the left channel side is also input to the peak hold circuit, so that the left channel side recording The setting position of the level setting volume is also controlled in the same way.

As described above, according to the automatic recording level setting circuit of the present invention, the recording level setting volume itself, which adjusts the level of the recording signal, detects the setting position. The setting position of the level setting volume can be controlled with a simple configuration and with high precision.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a human output characteristic diagram of the window comparator. (1) - Signal input terminal. (2) - Volume for recording level setting. (3)・-Switch circuit. (4)--Reference signal generation circuit. (9)--Peak hold circuit (1B)---Window comparator. (24)～・・・RC for motor drive.

Claims (1)

[Claims] (1) In an audio device in which the recording signal input during recording is level-adjusted with a recording level setting volume and then supplied to the recording circuit, when the level is set to control the setting position of the recording level setting volume. , level detection means for detecting the level of the recording signal supplied without going through the recording level setting volume; reference signal generating means for generating a recording reference signal of a predetermined level; position detection means for detecting the setting position of the recording level setting volume by comparing the level of the recording reference signal supplied from the reference signal generation means and the level of the recording signal detected by the level detection means; Automatic recording level setting for audio equipment, characterized in that a control means is provided for controlling the recording level setting volume to a setting position according to the level of an input recording signal based on the detection result of the position detecting means. circuit.