JPS6120708Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides a turntable in which a through hole is formed for detecting the size of a record, and a passage through the hole when a record is placed on the turntable. The present invention relates to a detection device for detecting the size of a record disc of a record player, etc., which performs the detection using a specific light to be controlled.

In the prior art of such a device, a light emitting source is installed in a suitable place in the upper space of the surface of the turntable (the surface on which the record is placed), while a light receiving means is installed in a suitable place in the lower space of the back side of the turntable. There is one in which the turntable is fixed and the light from the light emitting source can be received by a light receiving means through a through hole formed in the turntable corresponding to the size of the record.

In the case of such prior art, the mounting position of the light emitting source or the mounting and fixing position of the light receiving means must be set accurately with respect to the through hole, but the positioning is done by vertically positioning the turntable between them. This positioning work is very difficult because the discs are separated, and a considerable amount of effort is required for this positioning work in order to satisfactorily detect the size of the record disc.

On the other hand, as a prior art technique for avoiding this difficulty, there is a technique in which the hole diameter of the through hole of the turntable is increased so that the accuracy of the positioning described above may be lowered.

However, in any of the prior art techniques, increasing the hole diameter of the through hole often leads to record size detection errors and becoming more susceptible to the influence of external light.On the other hand, if the hole diameter is not increased, However, the mounting positions of the light emitting source and the light receiving means must be set extremely accurately, and as mentioned above, this setting is extremely difficult.

The purpose of the present invention is to provide a device for detecting the size of a record disc of a record player, the presence or absence of a record disc, etc., which solves the above-mentioned conflicting problems at once.

In summary, the present invention provides a light-emitting means and a light-receiving means as a unit under the back surface of the turntable, thereby making it easy to set the mutual mounting positions of the two means, and making it possible to easily set the mutual mounting positions of the two means, and to make the through-holes of the turntable. The diameter of the hole can be made sufficiently small so that the influence of external light can be ignored.

FIG. 1 is a side view of an apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 1. The figure is
This is a case where an EP record 1, which is a record with a diameter of 17 cm, is placed on the surface of the turntable 2. A turntable 2 is attached to a turntable drive shaft 4 extending vertically through a cabinet 3 of a record player so as to be held horizontally. Turntable 2 has a radius from its center axis.
Through holes 21 and 22 are provided at r ₁ and r ₂ (r ₁ < r ₂ ), respectively, and one of the through holes 21 is
The through hole 22 is located in a place that is covered by the record 1 when the record 1 is placed on the turntable, and the other through hole 22 is not covered by the EP record 1 and is located in a place that is covered by the record 1 when the record 1 is placed on the turntable. It is located in the area covered by the record when it is placed on the turntable.

On the cabinet 3 directly below the through-holes 21 and 22 are units 5 and 6 which are formed into a pair of light-emitting elements 51 and 61 and light-receiving elements 52 and 62, respectively.
is installed. The light from one unit 5 heads toward the through hole 21, and when the bottom surface of the EP record disc 1 faces the through hole 21, the light is reflected from the bottom surface, and the reflected light is received by the unit 5. The light is received by the element 52. This also applies to the other units 6.

Since the light-emitting element 51 and the light-receiving element 52 are integrated into a unit, irradiating the lower surface of the EP record facing the through-hole 21 with light and directing the light reflected from the lower surface toward the light-receiving element is the act of emitting light. This is much easier than when the element and the light-receiving element are not integrated into a unit as described above. Note that when an EP record is placed on the surface of the turntable, the light from the other unit 6 escapes directly above the turntable 2 through the through hole 22, so the light receiving element 62 of the unit 6 does not receive light. The light from the light emitting element 61 is not irradiated. In this case, there is a possibility that the external light may irradiate the light receiving element 62 through the through hole 22 of the turntable 2, but the hole diameter of the through hole 22 can be made sufficiently smaller than that in the prior art. , the light-receiving element 62 that receives the light from the light-emitting element 61 has a directivity such that it only receives light that enters in an oblique direction, and the probability that external light travels vertically downward is determined by the size of the hole diameter and the thickness of the turntable. Considering the fact that the light emitting element is expensive, the light from the light emitting element is intermittent light, and appropriate circuit processing has been performed, the above-mentioned fear is considered to be unlikely.

Naturally, when an LP record is placed on the turntable 2, the through-holes 21 and 22 are both covered by the record, and as a result, the light from the light-emitting elements 51 and 61 is directed toward the record from the through-hole. As the light is reflected by the disk, the light receiving elements 52 and 62 in the unit 6 are irradiated with this reflected light.

FIG. 2 is a block diagram of the internal circuit of the above device. A light emitting element 51 installed inside the units 5 and 6,
61, a rectangular pulse signal (timing signal) of a constant frequency is generated from the timing signal generation circuit 7.
Ts (see Figure 3) is applied. Light emitting element 5
In response to this signal Ts, 1 and 61 emit light that is intermittent at a constant frequency, and output portions of the light receiving elements 52 and 62 also output rectangular shaped first and second detection signals that match the frequency. Pulse signal S ₁ ,
S ₂ (see Figure 3) is derived. On the other hand, the signal Ts
is another signal comparison circuit 81 of the light emitting elements 51 and 61,
It is also applied to 82 and compared in its circuits 81 and 82 together with signals S ₁ and S ₂ . Signal comparison circuit 81, 8
Comparison output signals Sx and Sy (see FIG. 3) are derived from 2, respectively.

Next, detection of the record size, etc. based on the above circuit when the record is placed on the turntable will be explained.

(i) When a record is not placed on the surface of the turntable 2 As the turntable 2 rotates, any intermittent light from the light emitting elements 51 and 61 will be transmitted through the through hole 2.
1 and 22 toward the space above the surface of the turntable, the intermittent light reflected on the back surface of the turntable becomes part of the light that is lost at the through hole for the light receiving elements 52 and 62. 3. As shown in FIG. 1, the light receiving element 5
As the output signals S ₁ and S ₂ of No. 2 and 62, intermittent signals with some defects are obtained. Then, the signal comparison circuit 8
1 and 82 are the signal Ts and partially missing signals S ₁ and S ₂
As a result of the comparison operation, signals Sx and Sy having pulses are outputted from the circuit output section at positions corresponding to the above-mentioned defects. Then, the next-stage discrimination circuit 9 detects that the signals Sx and Sy are both partially pulsed signals of the same shape, and discriminates that no record is placed on the turntable 2.

(ii) When an EP record is placed on the surface of the turntable 2 In this case, the intermittent light from one of the light emitting elements 51 passes through the through hole 21 of the turntable because it is covered by the record. It is reflected by the surface of the record facing the hole 21, and the light is reflected by the light receiving element 52.
Head to. Therefore, the output signal _S1 of the light receiving element 52 has the same phase as the signal Ts as shown in FIG. , the frequency. However, the intermittent light from the other light emitting element 61 is transmitted through the through hole 2 of the turntable.
2 is not covered by the record, some parts do not face the light receiving element 62, and as shown in FIG.
As shown in , a partially missing signal S ₂ is output from the light receiving element 62 . As a result, a partially pulsed signal is obtained as the output signal Sy of the signal comparison circuit 82. Therefore, the signals Sx and Sy input to the discrimination circuit 9 are compared and discriminated there, and it is detected that an EP record is placed on the surface of the turntable.

(iii) When the LP record is placed on the surface of the turntable In this case, the light from both the light emitting elements 51 and 61 is covered by the record, so the through hole of the turntable is covered. Light receiving elements 52, 62
is irradiated as defect-free intermittent light. As a result, as shown in FIG.
The signals S ₂ and S ₁ of No. 2 and 62 are compared with the signal Ts in signal comparison circuits 81 and 82, and in the discrimination circuit 9, an LP record is placed on the surface of the turntable based on the comparison output signals Sx and Sy. Determine whether the

Note that FIGS. 1 and 2 show a case where external light is input to the light receiving element through the through hole (period T). It is clear that even if this external light illuminates the light receiving element, it will not affect the signals Sx and Sy for record disc detection. This is because the light emitted by the light emitting element is a constant intermittent light, and the signal Ts, S ₁ and S ₂ are processed by the theory of an exclusive OR circuit, etc.
This is because Sx and Sy are not affected.

As is clear from the above-mentioned embodiments, according to the present invention, since a device in which a light emitting element and a light receiving element are integrated is provided at an appropriate position below the back surface of the turntable, accurate positioning of the element is facilitated. In addition, the through hole of the turntable can be made sufficiently small, and the influence of external light can be eliminated. Moreover, in the present invention, the timing signal obtained from the timing signal generation circuit is used to drive each light emitting element, and is also used for comparison with the detection signal from the light receiving element in each signal comparison circuit, so the circuit configuration is This is an excellent idea that makes it easy.

[Brief explanation of the drawing]

1 is a side cross-sectional view of a device according to an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, FIG. 2 is a drive system circuit block diagram of the device, and FIGS. 3 1 and 2 ，
3 is a time chart for explaining the operation of detecting a record by the above device. 1... LP record, 2... Turntable, 3... Cabinet, 21, 22... Turntable through hole, 5, 6... Unit (51,
61; light emitting element; 52, 62; light receiving element).

Claims (1)

[Claims for Utility Model Registration] A turntable in which first and second through holes are provided at rollers with different diameters from the center; a timing signal generation circuit that generates a timing signal of a constant frequency; a first light emitting element installed below the turntable to correspond to the through hole and outputting intermittent light driven by the timing signal; and a first light emitting element that covers the first through hole on the turntable. a first light emitting element that receives intermittent light from the first light emitting element that is reflected from the first record when a record is placed thereon, and generates a first detection signal. a first unit; a second light emitting element installed below the turntable so as to correspond to the second through hole; and driven by the timing signal to output intermittent light; When a second record disc covering the second through hole is placed, intermittent light from the second light emitting element reflected from the second record disc is received and a second detection signal is generated. a second unit that compares the timing signal with the first detection signal and derives a first comparison output signal depending on the presence or absence of the first detection signal; a second signal comparison circuit that compares the timing signal and a second detection signal and derives a second comparison output signal depending on the presence or absence of the second detection signal; and a determination circuit for determining the size of the record placed on the turntable based on a second comparison output signal.