JPS6047202A - Inter-music detecting circuit of automatic music selection record player - Google Patents

Abstract

PURPOSE:To prevent malfunction due to a different record disc size and malfunction due to music-selection by providing a gain switching circuit of an amplifier or a reference voltage switching circuit of a comparator so as to detect surely the edge of record disc. CONSTITUTION:Since a switch 15 is turned on when an inter-music sensor 11 is placed at a reference position at the outer circumference of the record disc, an output Q of a RS flip-flop 14 goes to L, a feedback resistor of the amplifier 12 is only a resistor 18 and the gain is increased. In moving the inter-music sensor 11 in the direction of record edge, the switch 15 is turned off, and when an output pulse corresponding to the record edge is outputted from the comparator 13, the RS flip-flop 14 is inverted, a resistor 17 is connected in parallel with the resistor 18 and the gain of the amplifier 12 is decreased. Thus, while the inter- music 11 is placed in the vicinity of the outer circumference of the record disc, the gain of amplifier is kept higher and after the 1st pulse is detected at the record edge, the gain of amplifier is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a track interval detection circuit for an automatic music selection record player. .

Conventional configurations and their problems In recent years, record players with an automatic music selection function have become popular, and there is a need for more reliable operation.

The conventional song interval detection circuit will be explained below.0 Figure 1 shows a circuit diagram of the conventional song interval detection circuit, in which 1 is an optical song interval sensor that detects the song interval or record edge; An amplifier 3 amplifies the sensor output, and a comparator 3 compares the amplifier output with a reference voltage and outputs a signal.

Regarding the conventional song interval detection circuit configured as above,
The operation will be explained below.

As shown in FIG. 2(a), when the track sensor 1 passes over the record 4, the reflected output becomes large at the track intervals 6 and record edges 6, and conversely, the reflected output becomes small at the sound groove sections. Therefore, generally, an output as shown in FIG. 2(b) appears from the amplifier 2.

When this signal is compared at a threshold level of 7, a pulse signal representing a music interval 5 or an edge 6 is outputted as an output of the comparator 10.

However, in the above configuration, record edge 6
may not be detected. This is because the shape of the record edge 6 is not uniform, so depending on the record, the sensor amplification output at the edge 6 may become smaller than the threshold level 8 as shown in FIG. 2(C). In this case, the record edge 6 cannot be detected because it is not outputted as a cross, resulting in problems such as erroneous detection of the record size and errors in the song selection operation.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional problems by making it possible to reliably detect the edge of a record regardless of the difference in edge shape of the record, thereby preventing erroneous detection of record size and error in song selection operation. The purpose is to prevent.

Structure of the Invention The present invention includes a song interval sensor that detects the song interval on a record;
Automatic music selection comprising: an amplifier that amplifies the output of the inter-song sensor; a comparator that compares the output of the amplifier with a reference voltage and outputs a signal; and a switching circuit that switches the gain of the amplifier or the reference of the comparator. This is a track interval detection circuit for a record player, and can ensure record edge detection by increasing the amplifier gain 9 only for the first pulse and lowering the comparator threshold level.

DESCRIPTION OF EMBODIMENTS FIG. 3 shows a circuit diagram of a song interval detection circuit in a first embodiment of the present invention. In Figure 3, °11 is a sensor between songs, 12 is an amplifier that amplifies the sensor output, and 1
3 is a comparator that compares the amplifier output with a reference voltage and outputs a pulse; 14 is an RS flip-flop; 15
16 is an amplifier gain switching transistor; 18 is a feedback resistor of the amplifier 12; and 18 is a feedback resistor of the amplifier 12.

The operation of the song interval detection circuit of this embodiment configured as described above will be explained below. 0 First, song interval sensor 1
1 is at the reference position on the outer circumference of the record, switch 16
is on, so the output Q of RSS free lag flop 1
is set to L. Therefore, since the transistor 16 is turned off, the feedback resistance of the amplifier 16 is only the resistor 18.
The gain of amplifier 2 becomes high. At this time, when the song interval sensor 11 is moved toward the record edge, switch 1
6 is turned off, and when an output pulse corresponding to the record edge is output from the comparator 13, the R871 logflop 14 is inverted and its output Q becomes H, and the transistor 16 is turned on and the resistor 17 becomes the resistor 18. When connected in parallel, the gain of the amplifier 12 decreases.

As described above, according to this embodiment, by providing the amplifier gain switching circuit, the amplifier gain is kept high while the inter-track sensor 11 is located near the outer periphery of the record, and the amplifier gain is set high at the record edge. After the first pulse is detected, the amplifier gain can be lowered. Due to this,
The waveform as indicated by A in FIG. 2(C) also becomes as indicated by B in FIG. 5(-), making it possible to reliably detect the L record edge.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a circuit diagram of a song interval detection circuit showing a second embodiment of the present invention.

In the figure, 19 is a song interval sensor, 20 is an amplifier that amplifies the sensor output, 21 is a comparator that compares the amplifier output with a reference voltage and outputs a pulse, 22 is a threshold level switching transistor, and 23 is a R3
24 is a flip-flop; 24 is a sensor reference position detection switch; and 26 is a resistor for determining the current level. The difference from FIG. 3 is that the reference voltage of the comparator 21, that is, the comparator level, can be switched.

The operation of the circuit diagram of the second embodiment configured as described above will be described below.

First, when the inter-track sensor 19 is at the reference position on the outer periphery of the record, the switch 24- is on, so the output Q of the R8 frisogee flop 23 is at H level. therefore,
The threshold level of the comparator 21 at which the transistor 22 is turned on is determined by the division ratio of the resistors 26 and 27, and the threshold level is lower than when the resistor 26 is present. This time curve sensor 1
When the switch 9 is moved toward the record edge, the switch 24 is turned off, and the record edge pulse is turned off to the comparator 2.
When 1 is output, the output Q of the R8 flip-flop 23
is inverted and becomes L, transistor 22 is turned off and resistor 25 is connected in series with resistors 26 and 27, resulting in an increase in the threshold level.

As described above, according to this embodiment, by providing the Threnon-Yord level switching circuit, the threshold level can be set to be low until the first pulse input is input, and then become high thereafter.

Due to this, the waveform like A in Fig. 2(C) also becomes 5th waveform.
Since the sea urchin threshold level 27 is switched as shown in FIG. 3(b), detection becomes possible.

It goes without saying that the logic circuit portion in both embodiments can be replaced with a microprocessor.

Effects of the Invention By providing an amplifier gain switching circuit or a comparator (D reference voltage (threshold level) switching circuit), the present invention can reliably detect the edge of a record and prevent malfunctions due to record size. This can prevent malfunctions in music selection operations.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional song interval detection circuit, Fig. 2 is an output waveform diagram of a horizontal chord board and its optical song interval sensor, and Fig. 3 is a song interval detection circuit according to the first embodiment of the present invention. circuit diagram,
FIG. 4 is a circuit diagram of the inter-song detection circuit in the second embodiment of the present invention, and FIG. 5 is a waveform diagram of the inter-song sensor output in the embodiment of the present invention. 1.11. '19...Optical curve sensor, 6.
...Record, 5...Between songs, 7...
...Sound groove section, 8゜26.27 ...Comparator reference voltage (threshold level), 2,12
,20...Amplifier,3.13.21...
・Comparator, 14.23...RS flip-flop, 16.24...Song sensor reference position detection switch, 22.16...Transistor, 17.18, 25, 26.27...Resistance. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure (α9! (1)) Y Figure 3 Figure 4

Claims (1)

[Claims] A song interval sensor capable of detecting song gaps on a record. An amplifier that amplifies the output of the inter-track sensor, a comparator that compares the output of the amplifier with a reference voltage and outputs a pulse, and a switching circuit that switches the gain of the amplifier or the reference voltage of the comparator. A song interval detection circuit for an automatic music selection record player, characterized in that the gain of the amplifier is increased or the reference voltage of the comparator is decreased at the time of detection.