JPH0135285Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Technical field This invention relates to the improvement of optical sensors.
In particular, the present invention relates to an optical sensor that is arranged on a pickup cartridge or cartridge shell that is fixed to the tip of a tone arm and moves together with the tone arm, and is used to detect silent grooves between songs on a record.

(b) Background of the Technology Automatic music selection record players are designed to select music by counting the number of silent grooves between songs on a record. However, with conventional optical sensors, the sensitivity of the sensor changes when the tone arm is raised and lowered, so it is difficult to detect silent grooves. It was not possible to use the optical sensor to detect the end of a song or the end of a record. FIG. 1 shows a conventional optical sensor. The optical sensor, which is disposed on a pick-up cartridge or cartridge shell so as to move together with the tone arm, is attached to a base 1 and is fixed to the base 1. It is composed of a light emitting element 2 and a light receiving element 3, and the base body 1 is provided with a first passage 4 through which projected light passes and a second passage 5 through which reflected light passes. Therefore, the first and second passages 4 and 5 allow the light projected from the light emitting element 2 to be reflected by the silent groove 7 of the record 6 to efficiently reach the light receiving element 3, and to avoid the influence of external light. At a predetermined angle α to each other so as not to be affected by
It is drilled so that Therefore, as shown in FIGS. 1A and 1B, at the raised position of the tone arm, the amount of reflected light from the silent groove 7 becomes sufficiently large, making it easy to detect the silent groove. however,
When the tone arm is in the lowered position (playing state), the optical path becomes shorter as shown in FIG. As shown, since the elevation angle of the tone arm changes, the amount of effective light decreases, the amount of reflected light reaching the light receiving element 3 decreases, and the sensitivity decreases. As a result, even when the performance of a certain song on the record is finished and the record needle reaches the silent groove between songs, the optical sensor cannot detect that it is a silent groove, and the optical sensor cannot detect the silent groove. It was not possible to accurately perform random program selection, auto repeat, auto return, etc. using it as is.

(c) Main points of the invention The present invention was created in view of the above points, and by devising the shapes of the first and second passages formed in the base to which the light-emitting element and the light-receiving element are fixed, This ensures that a constant sensor sensitivity is always obtained regardless of the raised or lowered position of the tone arm.

(d) Embodiment Figure 2 is a circuit diagram showing an embodiment of the present invention.
Figure 2 A is a front sectional view showing the relationship between the optical sensor and the record when the tone arm is in the raised position, B is a side sectional view thereof, and C is the relationship between the optical sensor and the record when the tone arm is in the lowered position. 2 is a front sectional view, and D is a side sectional view thereof. In FIG. 2, 8 is a light emitting element such as a light emitting diode for projecting light onto the record 9; 10 is a light receiving element such as a photodiode for receiving the reflected light from the record 9; 11 is a base body to which the light emitting element 8 and the light receiving element 10 are attached and fixed; 12 is a first passage bored in the base body 11 for passing the light emitted from the light emitting element 8;
and 13 are second passages formed in the base body 11 to allow reflected light to reach the light receiving element 10.
The first and second passages 12 and 13 are bored in parallel in the base 11 according to the positions of the light emitting element 8 and the light receiving element 10, respectively, and are spaced apart from the adjacent side of the light emitting element 8 and the light receiving element 10. The outer walls of the first and second passages 12 and 13, which are the surfaces in which the tone arm is raised, take into consideration the path of light from the light emitting element 8 until it is received by the light receiving element 10, respectively. and is tilted inward toward just below the midpoint of the light emitting element 8 and the light receiving element 10 to the record disc 9, depending on the incident angle of the reflected light from the record disc 9 to the light receiving element 10,
The inner walls of the first and second passages 12 and 13, which are adjacent surfaces of the light emitting element 8 and the light receiving element 10, are arranged so that the light from the light emitting element 8 at the lowered position of the tone arm is received by the inner walls of the first and second passages 12 and 13, respectively. Element 10
Considering the path of the light until it is received by the record disc 9, the light receiving element 10 is inclined further inward from the outer wall according to the angle of incidence of the reflected light from the record disc 9 onto the light receiving element 10. That is, the angle formed by the outer walls of the first and second passages 12 and 13 is α as in the case of FIG. 1, but the angle formed by the inner walls is larger than the angle α. β, and as a result, the first and second passages 12 and 1
3 has a trapezoidal cross section. Moreover, as is clear from FIG. 2B, the first and second passages 12 and 13
The rear wall of the tonearm is vertical, but the front wall is sloped, and the slope of the front wall is determined according to the elevation angle of the tonearm.

When the tone arm is in the raised position, among the light projected from the light emitting element 8, the effective light that is reflected by the silent groove part 14 of the record disc 9 and reaches the light receiving element 10, as shown in FIG. 1 The light becomes parallel to the outer wall of the passage 12, and the light receiving element 10
A predetermined amount of reflected light is received. Further, as shown in FIG. 2B, the light projected from the light emitting element 8 becomes parallel light with the rear wall of the first passage 12 as a reference. Therefore, when the tone arm is in the raised position,
The optical sensor can accurately detect the silent groove between songs, as in the case of FIG. 1A.

Next, when the tone arm is in the lowered position, the optical path becomes shorter as shown in FIG. The amount of reflected light received by the light receiving element 10 is the same as in the case of FIG. 2A. Note that the angle β formed by the inner walls of the first and second passages 12 and 13 is
It is determined as appropriate depending on the distance between the bottom surface of the record board 9 and the record disc 9. Further, when the tone arm is in the lowered position as shown in FIG. 2D, the light projected from the light emitting element 8 becomes parallel light with the front wall of the first passage 12 as a reference, and as shown in FIG. The same as the case.

FIG. 2E is a bottom view of the base 11 of the optical sensor, and as is clear from the figure, the first and second passages 12
The opening ends of and 13 are wider than the insertion side of the light emitting element and the light receiving element, and are offset from the insertion side. Note that the opening shape of the first and second passages 12 and 13 is not limited to a rectangular shape, but may be circular or elliptical.

(E) Effects As described above, according to the present invention, the outer walls of the first and second passages are adjusted according to the angle of incidence of the reflected light from the record onto the light receiving element when the tone arm is in the raised position. The light-emitting element and the light-receiving element are tilted inwardly toward the midpoint of the record, respectively, and the first and second light-receiving elements are tilted inwardly toward the center point of the record, and the angle of incidence of the reflected light from the record at the lowered position of the tone arm is adjusted to the light-receiving element. Since the inner walls of the two passages are each inclined further inward than the outer wall, the amount of reflected light received by the light receiving element is roughly equal to the amount of light received by the light receiving element when the tone arm is in the raised position and when it is in the lowered position. This has the advantage that a single sensor can reliably detect the silent groove portion of a record even during a song selection operation with the tone arm in the raised position or during performance with the tone arm in the lowered position.

[Brief explanation of the drawing]

Figures 1A to 2D are cross-sectional views showing a conventional optical sensor, Figures 2A to 2E are cross-sectional views of an embodiment of the present invention, and Figure 2A is a front cross-sectional view of the tone arm in the raised position; is a side sectional view thereof, C is a front sectional view of the tone arm in the lowered position, D is a side sectional view thereof, and E is a bottom view of the base of the optical sensor. Explanation of main drawing numbers, 8... Light emitting element, 10... Light receiving element, 11... Base, 12... First passage, 13
...Second passage.

Claims (1)

[Scope of utility model registration request] It consists of a light emitting element, a light receiving element arranged side by side with the light emitting element, and a base body to which the light emitting element and the light receiving element are attached, and the light projected from the light emitting element is reflected by a record and the reflected light is transferred to the light receiving element. In the optical sensor configured to receive light, the base has a first path for the projected light and a second path for the reflected light.
The outer walls of the first and second passages are drilled in parallel with the light-emitting element and the light-receiving element depending on the angle of incidence of the reflected light on the light-receiving element at the raised position of the tone arm. The inner walls of the first and second passages are tilted inwardly toward just below the midpoint of the tone arm, and the inner walls of the first and second passages are tilted inwardly toward the outer wall, respectively, depending on the angle of incidence of the reflected light on the light receiving element at the lowered position of the tone arm. An optical sensor characterized by being tilted further inward.