JPS6333201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a track interval detection device for a record player, and can be used even when the track interval is narrow and the output of the track interval sensor is small, or when the pitch of the sound groove is rough and the sound groove is rough. Even if the output of the song interval sensor is large, a stable song interval detection output can always be obtained.

In recent years, when playing a record disc on which a plurality of songs have been recorded on a record player, a song interval detection device has come to be used to automatically play any song on the record disc.

FIG. 1 shows a conventional song interval detection device, in which an optical sensor consisting of a light emitter 1 and a light receiver 2 is installed at the tip of a tone arm or a sensor arm (none of which is shown) provided separately from the tone arm. 3
is provided, and as the arm moves, the optical sensor 3 is moved in the radial direction on the record disc 4,
The difference between the reflected output level at the sound groove of the record 4 and the reflected output level between songs is used to optically detect the intervals between songs on the record 4. The output of the sensor 3 is amplified by an amplifier circuit 5, the output at the sound groove section is removed by a slice circuit 6, the output difference between the sound groove section and the song is increased by a filter circuit 7, and the comparator 8 is further connected to a filter circuit. The output of filter 7 is compared with a threshold voltage, and if the filter output is higher than the threshold voltage, it is determined that there is an interval between songs, and the output thereof is input to microcomputer 9.

However, some records are cut with a variable pitch in order to widen the dynamic range, and the output of the sensor 3 changes drastically, increasing or decreasing even in the sound groove. When such a record is detected by a song interval detection device, even if the pitch is in the groove, if the pitch suddenly becomes rough from a small point, it may be mistakenly detected as an interval between songs.

The present invention provides a track interval detection device for a record player that solves these problems.

FIG. 2 is a block diagram of one embodiment of the present invention, and numerals 1 to 5 are the same as those in FIG. 1. 10 is a first comparator, 11 and 12 are first and second slice circuits, 13 and 14 are first and second filter circuits, 15 and 16 are second and third comparators,
17 is a logic means composed of a microcomputer.

Figure 3 shows the specific circuit, L,
R ₁ is the LED and resistor that make up the light emitter 1, Tr, R ₂ is the phototransistor and resistor that makes up the light receiver 2,
A ₁ , R ₃ to _{R 5} are an operational amplifier and a resistor that constitute the amplifier circuit 5, A ₂ and R ₆ are an operational amplifier and a resistor that constitute the first comparator 10, and D ₁ and VR ₁ are an operational amplifier and a resistor that constitute the first slice circuit 11. Component diodes and volumes, D ₂ and VR ₂ are diodes and volumes that configure the second slice circuit 12, C ₁ , A ₃ , R ₇ to _{R 9}
are capacitors, operational amplifiers, and resistors that constitute the first filter circuit 13; C ₂ , A ₄ , R ₁₀ to R ₁₂ are capacitors, operational amplifiers, and resistors that constitute the second filter circuit 14; A ₅ and R ₁₃ are the A 6 and R 14 are an operational amplifier and a resistor that constitute the second comparator 15, and A ₆ and R ₁₄ are an operational amplifier and a resistor that constitute the third comparator 16.

In the above configuration, the light emitted from the LED L is reflected by the record disc 4 and received by the phototransistor Tr. The output is amplified by the operational amplifier A ₁ and then input to the first and second slice circuits 11 and 12 and the first comparator 10 . At this time, the voltage +V _D (V _D
When a voltage exceeding the forward voltage drop of the diode is applied, the diode _D1 becomes conductive and a signal is transmitted to the first filter circuit 13, but when the voltage is lower than that, the voltage is fixed at a constant voltage. The signal then passes through the first filter circuit 13, where the S/
N is improved and input to the second comparator 15 and compared with the threshold voltage V _TH2 .

On the other hand, the voltage at the output point of the second slice circuit 12 is set higher than the voltage at the first slice circuit 11, and the subsequent operation is the same as described above.

Next, detailed operation of the above embodiment will be explained. First, before starting the performance, the sensor 3 moves over the record 4, and the arm position when the second and third comparators 15 and 16 rise from L to H is stored in the memory of the microcomputer 17. Each is stored as data between songs. Also, the number of times the first comparator 10 rises from L to H is stored in the memory of the microcomputer 17. When the movement of sensor 3 is finished,
The number of times the first comparator 10 rises is 1
If so, it is determined within the microcomputer 17 that the input from the second comparator 15 is valid, and if it is 2 or more, the input from the third comparator 16 is valid. That is, in any record, there is always a wide sound part at the end of the sound groove, and the output of the first comparator 10 always rises at least once in this part. Therefore, the cutting condition of the record is detected in advance depending on whether the number of rises is 1 or 2 or more, and one of the second and third comparators 15 and 16 is selected according to the result. That's what I do.

FIG. 4 shows a waveform from point to point when a record disc with narrow intervals between songs is detected. As shown in Figure 4, records with narrow track gaps generally have fine pitch pitches. Therefore, as shown in FIG. 4A, the voltage of the waveform at the point is low both between songs and between the grooves, and the voltage between songs does not exceed the threshold voltage V _TH9 of the first comparator 10, so at this time, the second The output of comparator 15 is selected. Since the output of the sound groove is cut off at a low slice voltage by the volume VR ₁ of the first slice circuit 11, the signal between songs is hardly affected as shown in FIG. S/ through filter circuit 13
N is improved and then the second comparator 15
is compared with the threshold voltage V _TH2 at .
As a result, as is clear from FIG. 4C, all the song gaps are correctly detected. At this time, if the output of the third comparator 16 is used,
As shown in FIG. 4E, two locations in the middle of the song are not detected.

FIG. 5 shows a waveform from point to point when a record with a sharp change in the pitch of the sound groove is detected. Generally, records with sharp pitch changes have thicker gaps between songs to make it easier to understand. Therefore, all of the inter-song signals appearing at the point exceed the threshold voltage V _TH1 of the first comparator 10, and the number of rises from L to H becomes two or more. Therefore, in this case, the third comparator 16 is selected, and as shown in FIG. 5E, the inter-song signal compared with the threshold voltage V _TH3 is extracted. If the output of the second comparator 15 is used at this time, as shown in FIG. 5C, there is a portion in the sound groove where the threshold voltage V _TH2 is exceeded, and this portion will be mistakenly detected as a song interval.

Note that in the above embodiment, the first comparator 10
Provide only one threshold voltage V _TH1 for L
One of the two comparators 15 and 16 is selected depending on the number of rises from to H, but two or more threshold voltages of the first comparator 10 are provided, and three or more systems are selected depending on the output. Alternatively, one of the comparators may be selected.

In addition, in the embodiment, the second and third comparators 1
Although the outputs of Nos. 5 and 16 are temporarily stored in the memory, substantially the same operations can be performed without using any particular memory.

As described above, the present invention allows the output of the sensor to be
The cutting status of the record is detected by inputting the input into the comparator and comparing the threshold voltage with the sensor output, and based on the detection result, the comparator with the optimal detection ability according to the record is selected. Therefore, it is possible to perform song interval detection with less risk of false detection regardless of the type of record.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional example, FIGS. 2 and 3 are block diagrams and circuit diagrams of an embodiment of the present invention,
FIG. 4 and FIG. 5 are explanatory diagrams of the operation. 1... Light emitter, 2... Light receiver, 3... Song sensor, 4... Record disc, 5... Amplification circuit, 10
...first comparator, 11, 12...first,
Second slice circuit, 13, 14...first, second
filter circuit, 15, 16...second and third comparators, 17...logic means (microcomputer).

Claims (1)

[Claims] 1. An inter-song sensor that is composed of a light emitter and a light receiver and moves on the record; a first comparator that compares the output of the inter-song sensor with a reference voltage; first and second slice circuits having different values, first and second filter circuits and second and third comparators continuously connected after the first and second slice circuits, and the first and second comparators of the first comparator. A track interval detection device for a record player, comprising logic means that selectively uses the outputs of the second and third comparators as inter-track signals in accordance with the outputs. 2. In claim 1, the logic means has a memory for storing the outputs of the second and third comparators, and before the start of the performance, the inter-piece sensor is moved over the record to record the outputs of the second and third comparators. A track interval detection device for a record player, characterized in that the output of the third comparator is stored in the memory, and the data stored in the memory is selected according to the output of the first comparator.