JPS5918766B2 - Tape recorder recording adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording level and recording equalizer adjustment device for a tape recorder.

To adjust the recording system of a tape recorder, for example, 40
How to adjust the recording signal level so that the signal at the specified recording level flows to the head when the recording level meter indicates "OVU" with the 0H2 input signal, and how to compensate for high frequencies in the recording equalizer circuit. 10KH
A method has been adopted in which equalizer compensation is adjusted using the input signal No. 2 according to instructions from a level motor. Adjustment of such a recording system is performed manually by an adjuster while visually observing a level meter, but such adjustment requires a certain degree of skill and time. SUMMARY OF THE INVENTION An object of the present invention is to provide a recording adjustment device for a tape recorder that can appropriately adjust the recording system using a simple method.

Hereinafter, the present invention will be explained using the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
The 0Hz and 10KHz signals are set to normal (NORML) via the level (LEVEL) and EQ adjustment switch S1.
) and the test terminals of the test (TEST) switch S,. A normal audio signal to be recorded is applied to the normal terminal of the switch S. The signal passing through the switch S is input to the line amplifier 1, where it is amplified and then its level is varied by a recording level adjuster 2 having a variable resistor.

Thereafter, the signal is amplified by a recording amplifier 3 having an equalizer function, and at this time, an equalizer adjuster 4 adjusts the amount of high-frequency compensation. On the other hand, a 100 KHz AC bias signal is generated by an oscillator 5, adjusted to a predetermined bias level by a bias adjuster 6, and output. The bias signal and the output of the recording amplifier 3 are superimposed and recorded on the tape 8 by the recording head 7. The recorded signal is regenerated into an electric signal by the reproducing head 9 and then sent to the reproducing amplifier 1.
amplified at 0.

A rectifier circuit 11 and a smoothing circuit 12 are provided in order to subsequently generate a DC voltage according to the reproduced signal level. The smoothed output is inputted via a buffer amplifier 13 to a comparison circuit 14 at the next stage. The comparison circuit 14 is constituted by a so-called window comparator. That is, the first and second reference voltages generated by the voltage dividing circuit made up of the low resistors R1 to R, and 2 are compared with the previous DC voltage, and the input voltage is the first reference voltage, The first control signal A is set when the voltage is smaller than , the second control signal B is set when the voltage is between the first and second reference voltages 1 and 2, and the second control signal B is set when the voltage is larger than the second reference voltage 2. It is configured to generate a third control signal C respectively. These first to third control signals drive the first to third display elements, e.g., light emitting diodes, respectively, and the first to third display elements, e.g., light emitting diodes (LEDs) D1 to D, to turn on. FIG. 2 is a circuit diagram showing a specific example of the comparator circuit 14 in FIG. It consists of a pair of transistors Q whose emitters are commonly connected, and a second differential circuit having Q4.

First and second reference voltages, . . . are applied to the bases of the transistors Q and Q4, respectively, and an input voltage is applied to the bases of the transistors Q and Q, respectively. The collector outputs A, B, and C of the transistors Q, Q4, and Q drive the diodes D, D, and D, respectively. Here, when the input voltage 1N is smaller than the reference voltage, the transistor Q is off and the transistor Q is on, so the collector output A of the transistor Q turns on the diode D1, and the input Indicates that the voltage is less than the reference voltage 1.

When the input voltage 1N is between the first and second reference voltages 1 and , transistor Q2 is off and transistor Q, is on, and transistor Q, is off and transistor Q4 is on. Therefore, the diode D is turned on by the collector output B of the transistor Q4. When the input voltage 1N is higher than the second reference voltage, transistors Q1 and Q are turned on, so the collector output C of transistor Q turns on diode D, which causes a so-called window comparator. It operates as follows. In the configuration shown in FIGS. 1 and 2, adjustment of the recording level will first be described.

The switch S is switched to the test side and the switch S1 is switched to the level side, and a 400 Hz signal is applied to the input of the line amplifier 1. Recording is performed on the tape 8 by appropriately turning the adjustment knob (not shown) of the level adjustment circuit 2. This recorded signal is simultaneously reproduced by the reproducing head 9 and converted to a DC level by the rectifying circuit 11 and the smoothing circuit 12. This DC voltage is compared with a reference voltage 1, . by a comparator circuit 14. Now, by selecting the reference voltages V, V2 to playback DC levels corresponding to the maximum and minimum values of the optimal recording level or its vicinity, the recording level will be properly adjusted when the diode D, lights up. will be done. Furthermore, if the diode D1 or D lights up, it becomes possible to determine whether the recording level is low or high, respectively. Therefore, set the recording level adjustment knob to MAX (maximum) accordingly.
Alternatively, the diode D2 can be adjusted by rotating it in the MIN (minimum) direction so that the diode D2 lights up. For EQ compensation adjustment of the recording equalizer, set switch S2 to the test side.
Each switch S1 is switched to the EQ side, and a 10 KHz signal is applied as an input to the line amplifier 1.

In this case as well, by appropriately setting the reference voltages V1 and V2, simple adjustment can be made by visually observing the LED display. Various forms of display can be considered, but it is best to use a form that the adjuster can easily distinguish.For example, as shown in Fig. 3, diodes Dl, D2, and D3 are arranged in order from the right side and displayed as 〉, O, and 〉, respectively. Shape.

Then change each display to "MAX direction", "JUST" and "
Although the shape can be easily adjusted by setting the shape to "in the MIN direction", the shape is not limited to the shape shown in FIG. As described above, according to the present invention, recording level and EQ
Adjustment can be performed very easily, and even if an expert in the field of adjustment performs the adjustment, all he has to do is follow the LED display, so there is an advantage that the adjustment can be performed simply and in a short time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the comparison circuit in FIG. 1, and FIG. 3 is a plan view showing the display form of a display element. Explanation of symbols of main parts 2...Level adjuster,
3... Recording amplifier, 4... EQ adjuster, 11... Rectifier circulation, 12... Smoothing circuit, 14... Comparison circuit , D, ~D3...
・Display element, Q1 to Q4...transistor.

Claims (1)

[Scope of Claims] 1. A variable means for varying the level of a predetermined signal, a recording means for recording on a tape the predetermined signal whose level has been varied by the variable means, and a recording means for converting the signal recorded on the tape into an electrical signal. a reproduction means for reproducing; a means for generating a DC voltage according to the reproduction level of the electrical signal; the first control signal when the voltage is smaller than the voltage;
A comparison of generating a second control signal when the DC voltage is between the first and second DC voltages, and generating a third control signal when the DC voltage is greater than the second reference voltage. and first, second, and third display elements that are driven to turn on by the first, second, and third control means, respectively, and the first display element has a level of the predetermined signal. The second display element indicates that the level of the predetermined signal is at or near the optimum value, and the third display element indicates that the level of the predetermined signal is at or near the optimum value. A recording adjustment device for a tape recorder, characterized in that the recording adjustment device indicates that the value is larger than the optimum value. 2. Claim 1, wherein the means for generating the DC voltage includes a rectifier circuit that rectifies the reproduction output of the reproduction means, and a smoothing circuit that smoothes the rectified output of the rectifier circuit. Recording adjustment device for the described tape recorder. 3. The comparing means includes a first differential circuit having first and second transistors whose emitters are commonly connected, and a second differential circuit having third and fourth transistors whose emitters are commonly connected to the collector of the first transistor. a differential circuit, wherein the DC voltage is applied to each base of the first and third transistors, and the first and second reference voltages are applied to each base of the second and fourth transistors, respectively. and the respective collector outputs of the second, fourth and third transistors are used as the first, second and third control signals, according to claim 1 or 2. Recording adjustment device for tape recorders. 4. The recording adjustment device for a tape recorder according to claim 1, 2 or 3, wherein the variable means is a recording level adjuster. 5. Claim 1, wherein the variable means is a recording compensation amount adjuster in a recording equalizer circuit.
3. The recording adjustment device for a tape recorder according to item 1, 2 or 3.