JPS61158002A - Intermusic detecting device - Google Patents

Abstract

PURPOSE:To detect intermusic accurately without being influenced by disturbing light by detecting level of only signals of within specified range of frequency and detecting level of difference signal of sensors arranged symmetrically during tracing. CONSTITUTION:Light receiving devices 3a, 3b are arranged nearly symmetrically to tangent line of modulated grooves of a disk record R. Output of one light receiving device 3a including DC component is amplified by a pre-DC amplifier 4 and inputted to a band passing device 11 and an input terminal of a differential amplifier 16. Output of another light receiving device 3b is inputted to another input terminal of the differential amplifier 16 through a pre-DC amplifier 15 that amplifies inclusive of DC component. The intermusic at the time of searching is detected by inputting output of the band passing device 11 to a comparator 6 and comparing with reference potential V1 of a reference potential generator 7. Further, the intermusic during tracing is detected by inputting output of the differential amplifier 16 to a comparator 8, and comparing with reference potential V2 of a reference potential generator 9. Further, the output of the differential amplifier 16 is inputted also to a comparator 17, and compared with reference potential of almost zero.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a song interval detection device for detecting song intervals on a record disc played on a record player or the like.

[Conventional technology]

In recent years, record players that are capable of a so-called programmed song selection operation in which desired songs are specified and played in a desired order, rather than playing back the sound grooves of a record in order from the beginning, have become popular. Such a record player requires a function to detect the intervals between songs on a record.

FIG. 6 shows a block diagram of a conventional song interval detection device for detecting such song gaps. In the figure, reference numeral 1 denotes a sensor consisting of a light emitting means 2 such as a light emitting diode and a light receiving means 3 such as a phototransistor.
Emitted from.

Records are becoming more and more light. 4 is a preamplifier that preamplifies the minute signal from the light receiving means 3 including a DC component;
5 is a DC amplifier for further DC amplifying the output.

The output of the DC amplifier 5 is supplied to a comparator 6, where it is compared with a predetermined base potential V□ outputted by a reference potential generator 7, and also supplied to a comparator 8, where it is compared with a reference potential V□ outputted by a reference potential generator 9. It is designed to be compared with potential ■2.

Compared to open areas where musical tone signals etc. are recorded, the spacing between the sound grooves is coarser between songs, so in open areas there is less reflected light due to scattering, etc. Between songs, there is less scattering, so the reflection scene is There will be more. Therefore, for example, when searching between songs by separating the pickup from the record and moving it in the radial direction at a predetermined speed, the result shown in FIG. When the output of the light receiving means 3 is compared with the reference potential V1 by the comparator 6 as shown in FIG. ) is obtained. In the open region, the output of the DC amplifier 5 does not exceed the reference potential V□, so no such pulse is output.

On the other hand, when placing the pickup stylus on the record and tracing the sound groove, the pickup is closer to the record than when searching, and the amount of reflected light received by the light receiving means 3 increases, so there is a difference between songs. Of course, the level of the output of the DC amplifier 5 becomes high even in the open region (see Fig. 7).
d)). Therefore, by providing a reference potential v2 higher than the reference potential v1 and comparing this with the output of the DC amplifier 5 (FIG. 7(e)), the inter-song detection pulse can be obtained from the comparator 8 ( Figure 7(f)).

FIG. 8 shows another conventional example. Note that parts corresponding to those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted (the same applies below). In this example, the output of the preamplifier 4 is passed through the bandpass means 11 to the comparator 6.
It is now possible to manually detect the gaps between songs when searching. Furthermore, in order to detect the interval between songs during tracing, instead of using the signal from the light receiving means 3, the left and right reproduced musical tone signals obtained from the pink-up are sent to the preamplifier 1.
2.13, the output is added and amplified by the amplifier 14, and the level is set to a predetermined reference potential ■2 by the comparator 8.
I try to compare it with.

[Problem that the invention seeks to solve]

However, in the conventional example shown in FIG. 6, when light is applied from the outside during a search operation in which the pickup and the record are moved apart, the light is incident on the light receiving means 3, and the preamplifier 4 and the DC amplifier Since the DC component signal is amplified by the comparator 5, the level of the signal input to the comparator 6 becomes higher than the reference potential V1, resulting in malfunction.

In addition, in the embodiment shown in FIG. 8, since the playback signal of the musical tone recorded on the record is used to detect the interval between songs being traced, the circuit becomes complicated and the cost increases. When there is a record of applause between songs, such as on a live recording record, and there is no silence, or when there are parts of a song that are close to silence, such as classical music with a wide dynamic range. It had the drawback of malfunctioning.

In addition, in any of the conventional examples, since the inter-song detection pulse has a width, it is impossible to detect the center between the inter-songs, especially at the end of a song, and the center of the inter-song detection pulse cannot be detected before the reproduction of the musical tone signal is completely completed or when the next song is detected. There was a drawback that the pickup was likely to be raised (or lowered) after it had been played a little.

[Means for solving problems]

FIG. 1 and FIG. 2 show the configuration of the song interval detection device of the present invention. In the present invention, as shown in FIG. 2, at least two light receiving means 3 are provided in the sensor 1 consisting of a light emitting means 2 and a light receiving means 3. One light receiving means 3
a and the other light receiving means 3b are arranged approximately symmetrically with respect to the tangent of the sound groove of the record R, and the light emitting means 2 emits light toward the record R, so that the needle of the pickup cartridge of the record R Reflected light from a position slightly shifted by an approximately equal distance to the left or right of the location to be traced is received by each of the light receiving means 3a, 3b. The output of one of the light receiving means 3a is amplified including the DC component by a pre-amplifier 4, and then a band pass means 11 which passes and amplifies signals in a predetermined frequency range, and a differential amplifier 1.
It is input to one input terminal of 6. The output of the other light receiving means 3b is input to the other input terminal of the differential amplifier 16 via a pre-direct current amplifier 15 which amplifies the direct current component as well. The output of the bandpass means 11 is input to the comparator 6 and compared with the reference potential (2) of the reference potential generator 7, thereby detecting the interval between songs during the search. Further, the output of the differential amplifier 16 is input to a comparator 8 and compared with a reference potential V2 of a base NP potential generator 9 to detect a song interval during tracing. Further, the output of the differential amplifier 16 is also input to a comparator 17, and is compared with a reference potential of approximately zero.

For example, as shown in FIG. 3, the bandpass means 11 has its inverting terminal supplied with an input signal through a series circuit of a resistor 21 and a capacitor 22°, its non-inverting terminal being grounded via a resistor 23, and its It can be constructed by an operational amplifier 26 in which a parallel circuit of a capacitor 24 and a resistor 25 is feedback-connected between an output terminal and an inverting terminal. The frequency characteristics of such bandpass means 11 are as shown in FIG.

That is, it has a low cutoff frequency f, and a high cutoff frequency [2, and cuts off a signal containing a DC component with a frequency lower than the low cutoff frequency f1 and a signal with a frequency higher than the high cutoff frequency f2. It is designed to pass only the signals of The frequency between songs determined by the speed at which the pickup is moved in the radial direction of the record during the search and the interval (width) between songs on the record is between the low cutoff frequency f1 and the high cutoff frequency f. is set to be included. That is, the widest interval between songs is W□, and the narrowest interval is W2. When the search speed of the pickup is V, the low cutoff frequency f1 is V/2W1, and the high cutoff frequency f2 is V
/2W2.

[Effect]

The operation will be explained with reference to FIG.

The output of the light receiving means 3a (FIG. 5(a)) is DC amplified by the pre-direct current amplifier 4 and supplied to the band pass means 11. During the search, the frequency of the inter-track signal is included between the low cutoff frequency f1 and the high cutoff frequency f2 of the bandpass means 11, and is therefore transmitted to the comparator 6, but the frequency of the signal in the surface area is low. Since it is outside the range of the high-frequency cutoff frequency f□ and the high-frequency cutoff frequency f2, it is cut off and is not input to the comparator 6 (FIG. 5(b)). Therefore, only the inter-song signal is compared with the reference potential v1, and a detection pulse is obtained (Fig. 5 (
d)). The spacing between songs on a record varies, but for example, when the pickup search speed is ICMl/S, the maximum spacing W1 between songs is 0.1cm, and the minimum spacing W2 is 0.03cm, the low cutoff frequency f1 is about 5 Hz, and the high cutoff frequency f2 is about 17 Hz, and as a result of experiments, when set within this range, it was possible to successfully detect only inter-track signals on various records. Disturbance light such as sunlight is mostly direct current, and its frequency is lower than the low cutoff frequency f1, and disturbance light such as fluorescent lights is 5o or 607, so it is outside the high cutoff frequency f2, and the effects of these are There aren't many.

On the other hand, when the pickup reaches an interval while tracing the record, the amount of light received by one of the light receiving means 3a and 3b increases once, reaches a peak, and then decreases again (Fig. 5 (e)). The phenomenon is slightly delayed (out of phase) in the light receiving means 3a.

It also occurs on the other side of 3b. Therefore, the difference signal between the signals of the light receiving means 3a and 3b, which is obtained by the differential amplifier 16 and is outputted via the pre-direct current amplifier 4.15, is as shown in FIG. 5(g). Abbreviation S where the level is reversed to positive or negative
It has character-like characteristics. When the output of the differential amplifier 16 is input to the comparator 8 and compared with the reference potential v2, an inter-song detection pulse as shown in FIG. 5(h) is obtained.

As is clear from the figure, this pulse is generated just before the center of the song arrives. Further, the output of the differential amplifier 16 is compared with a substantially zero reference potential (ground potential) by a comparator 17. The output of the comparator 17 once becomes a high level between songs, and then inverts and becomes a low level at the center of the song (at the zero cross of the output of the differential amplifier 16) (see FIG. 5).
i)) By detecting this reversal, the center between songs can be detected. This makes it possible to particularly accurately detect the end position of a song. Furthermore, by utilizing this, even when a song gap is detected during a search, playback can be started accurately from the center of the song gap. That is, as is clear from FIG. 2, there is a gap between the position detected by the light receiving means 3a (approximately the center of the light source 2 and the light receiving means 3a) and the position of the needle tip (not shown) (approximately right below the light source 2). is a slight distance (shift)
Therefore, the inter-song detection pulse during the search in FIG. 5(d) is obtained just before the center of the inter-song. Therefore, when this pulse is obtained, the search operation is shifted to the trace operation, the arm is lowered, and the above-mentioned inter-track detection in the trace is performed, and when the inverted signal shown in Figure 5 (i) is obtained, the By turning off the muting relay (none of which is shown), it becomes possible to start playback from the center of the song. The disturbance light acts on the light receiving means 3a, 3b in almost the same phase, and the differential amplifier 16 removes the in-phase component, so its influence can be almost ignored.

Even if they act in opposite phases, the pickup (sensor 1) and the record are close to each other during tracing, unlike when searching, and sensor 1 is generally attached to the head shell where the pickup cartridge is attached. Since it is fixed inside facing the record, almost no disturbance light enters the light receiving means 3, and practically there is no effect on it.

If a signal is output from comparator 6 during tracing,
Even if a signal is output from the comparator 8 or the comparator 17 during the search, no problem arises because a control circuit such as a microcomputer connected at a subsequent stage can distinguish between these and select only the necessary signal. However, during tracing, the speed of the pickup is different (slower) than during searching, so the signals between one song have different frequencies and can hardly pass through the band pass means 11 (
(FIG. 5(f)), the comparator 6 does not output a detection pulse because it does not become higher than the reference potential v1.

Also, during the search, the output of the differential amplifier 16 is as shown in FIG.
It appears as shown in c), but since the level is smaller than the reference potential v2 as described above, the comparator 8 does not output a detection pulse. On the other hand, since the reference potential of the comparator 17 is approximately zero, it outputs a pulse that is inverted at the center between songs. Therefore, even during a search, it is possible to accurately detect the center between songs using this output.

Note that the comparator 6.8.17 only needs to be able to detect a level, and can be constructed from a discrete transistor or the like. Furthermore, although the bandpass means 11 is configured as an inverting amplifier in FIG. 3, it may also be configured as a non-inverting amplifier. Furthermore, what is formed on the record does not have to be a sound groove, but it is sufficient if the track is structured so that the reflectivity is different between each song and in the concave area. Also, a pre-installed DC amplifier 4.
15. If the amplification degrees of the bandpass means 11 and the differential amplifier 16 are appropriately adjusted, the reference potential v2 does not necessarily have to be greater than the reference potential V□.

〔effect〕

As described above, in the present invention, the sensors are arranged symmetrically with respect to the tangent line of the track, and during the search, among the signals from at least one sensor, a signal with a frequency lower than the low cutoff frequency containing a DC component and a signal with a high frequency It cuts off signals with frequencies higher than the cutoff frequency, detects the level of only signals in a predetermined frequency range between them, and detects the level of the difference signal of symmetrically arranged sensors during tracing. Therefore, without increasing the cost,
It is possible to accurately detect intervals between songs without being affected by external light either during a search or during a trace. It is also possible to detect the center between songs.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the song interval detection device of the present invention, Fig. 2 is a sectional view of the sensor, Fig. 3 is a circuit diagram of its band passing means, Fig. 4 is its frequency characteristic diagram, and Fig. 5 6 is a block diagram of a conventional song interval detection device, FIG. 7 is a waveform diagram thereof, and FIG. 8 is a block diagram of another conventional song interval detection device. 1...Sensor 2...Light emitting means 3...Light receiving means 4.15...Previous DC amplifier 5...DC amplifier 6.8.17...Comparator 7.9...Group $ Potential generator 11...Band pass means 12.13...Preamplifier 14...Amplifier 16.
... Differential amplifier 26 ... Operational amplifier and above Figure 1a Figure 2 (a) (b) (c)
(e) (f) (Q)
Figure 3 7'4 Figure 4 (d)

Claims (9)

[Claims] (1) It has a light-emitting means and a light-receiving means fixed at a predetermined position of a pickup that traces a track on a record, the light emitted from the light-emitting means is irradiated onto the record, and the reflected light is reflected by the light-receiving means. a track interval detection device for detecting intervals between tracks formed on a record disc with coarse spacing by receiving light with a means, wherein at least two light receiving units are arranged approximately symmetrically with respect to tangents of the tracks; and a signal containing a DC component with a frequency lower than the low cutoff frequency among the signals from at least one of the light receiving means, and a signal with a frequency higher than the high cutoff frequency, and a predetermined frequency range therebetween. a band-pass means for passing the signal, a comparison means for comparing the signal from the band-pass means with a predetermined reference potential, a differential amplifier for taking the difference between the outputs of one and the other of the light-receiving means; detection means for detecting a signal from the amplifier, and when the pickup searches between the songs on the record, the output of the comparison means is used, and the pickup traces the track on the record. A song interval detection device characterized in that the song interval is detected from the output of the detection means. (2) The detection means has another comparison means for comparing the output of the differential amplifier with a reference potential different from the reference potential of the comparison means. Song interval detection device. (3) The detection means has further comparison means for comparing the output of the differential amplifier with a substantially zero reference potential. Detection device. (4) During the search operation, the comparison means compares the signal from the bandpass means with the predetermined reference potential. When the comparison means detects the song interval, the search operation shifts to the trace operation, and the differential amplifier 4. The song interval detection device according to claim 3, wherein the muting is canceled when or immediately after the further comparison means for comparing the output with a reference potential of approximately zero outputs the output. (5) The predetermined frequency range of the bandpass means is set to include the frequency between the songs determined by the speed at which the pickup searches between the songs and the interval between the songs. A song interval detection device according to any one of claims 1 to 4, characterized in that: (6) The bandpass means includes at least one operational amplifier, and a resistor and a capacitor connected to the operational amplifier, according to any one of claims 1 to 5. song interval detection device. (7) The widest interval between the songs is W_1, the narrowest interval is W_2, and the speed when searching for the pickup is V_1.
The song interval detection device according to claim 5 or 6, wherein the low cutoff frequency is determined by V/2W_1 and the high cutoff frequency is determined by V/2W_2. (8) When the speed V is about 1 cm/s, the low cut-off frequency is about 5 Hz, and the high cut-off frequency is about 17 Hz. Detection device. (9) One signal from the light receiving means is supplied to the bandpass means via a pre-direct current amplifier, and a part of the output of the pre-direct current amplifier is further supplied to one input terminal of the differential amplifier. Claims 1 to 8 are characterized in that the other signal from the light receiving means is input to the other input terminal of the differential amplifier via another pre-direct current amplifier. The song interval detection device according to any one of.