JPH04268275A - Tape end detecting mechanism - Google Patents

Abstract

PURPOSE:To prevent erroneous detection of a tape end due to reflected light and disturbing light by disposing an optical path limiting plate in the vicinity of a light receiving element and positioning a light passing hole of the limiting plate on a straight line connected between a light emitting element and the light receiving element. CONSTITUTION:When a tape cassette 2 is loaded into a cassette loading part, the optical path limiting plate 35 is inserted into a tape drawing recessed part 10 of a cassette case 3. Then, since the light passing hole 46a of the limiting plate 35 is disposed in a position comparatively close to the light receiving elements 33 and 33', irradiating light to the elements 33 and 33' is limited to only light advanced on the straight line connected between the elements 33 and 33' and the light emitting element 31. Consequently, light reflected by a mechanical chassis surface, etc., and passed through a notch 12a and light made incident upon the recessed part 10 and passed through the notch 12a, etc., are interrupted by a side wall 46 of the plate 35.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention comprises a light emitting element and a light receiving element provided in a cassette mounting part, and the light emitting element is inserted into the inside of a cassette case when a tape cassette is mounted in the cassette mounting part. The end of the tape is detected by facing a light-receiving element across the tape path inside the tape cassette, and the light emitted from the light-emitting element passes through the transparent end of the tape and irradiates the light-receiving element. This is a tape end detection mechanism that can limit the light irradiated to the light receiving element to only the light that goes directly from the light emitting element to the light receiving element, thereby preventing the tape end from being mistakenly detected due to so-called disturbance light. In addition to being able to reliably prevent this, the above-mentioned restriction of the light irradiated to the light receiving element can always be performed with a constant optical path regardless of the tape cassette used; It is an object of the present invention to provide a tape end detection mechanism that does not increase the size of a cassette mounting section.

0002

2. Description of the Related Art Tape players normally have a device for detecting when the tape is running to the end of the tape, that is, when the tape has been fed out from either one of the two tape reels. A tape end detection mechanism is provided.

Various types of such tape end detection mechanisms have been proposed in the past, and one of them is
A light emitting element and a light receiving element are provided in the cassette mounting part where the tape cassette is mounted, and the light emitted from the cassette mounting part passes through the transparent end of the tape and is irradiated onto the light receiving element, thereby causing the tape to end. There is something that allows it to be detected.

FIG. 8 shows an example a of a conventional tape end detection mechanism having such a structure.

In the figure, b is a light emitting element, c and c' are light receiving elements, and these light emitting element b and light receiving elements c and c are
'' is supported by a mechanical chassis (not shown) of a cassette mounting part to which a tape cassette d is detachably mounted;
The two light receiving elements c and c' are arranged at substantially opposite positions with the light emitting element b interposed therebetween.

[0006] e, e is a reel stand, f is a tape cassette d
The cassette cases g and g' are tape reels rotatably housed inside the cassette case f.

h is a magnetic tape, and both ends of the magnetic tape h are fixed to tape reels g and g' separately, and are wound by a predetermined amount, and are connected to two tape reels g and g'. The part between the tapes passes through the tape outlets i formed at both ends of the front surface of the cassette case f.
The object is then taken outside and forced to follow a predetermined path.

j and j' are light passing holes formed on the left and right side walls of the cassette case f, k is an insertion hole formed on the bottom wall of the cassette case f, and the tape cassette d is installed in the cassette mounting section. When the two tape reels g and g' are respectively engaged with the two reel stands e and e, the light emitting element b is inserted through the insertion hole k and projected into the inside of the cassette case f, and The light-receiving elements c and c' are relatively located at positions facing the inside of the cassette case f from the light passing holes j and j' on both left and right sides of the cassette case f, and the light-receiving elements c and c' are located at positions facing the inside of the cassette case f from the light passage holes j and j' on both the left and right sides of the cassette case f, and are connected to the tape reels g and g' of the magnetic tape h and the tape. It faces light emitting element b across the portion located between exits i and i.

Note that portions l and l' of a certain length at both ends of the magnetic tape h are made of transparent leader tape.

As shown by the solid line in FIG. 8, when the magnetic tape h has been completely fed out from one tape reel g (hereinafter referred to as "T reel"), one light receiving element c, that is, , a transparent leader tape l is placed between the light-receiving element c and the light-emitting element b, which are closer to the T-reel g, so that the light emitted from the light-emitting element b and directed towards one of the light-receiving elements c passes through the leader tape l. The light passes through and is irradiated onto the light receiving element c,
Since the opaque part of the magnetic tape h is located between the other light receiving element c' and the light emitting element b, the light directed from the light emitting element b to this light receiving element c' is blocked by the magnetic tape h, and as a result, One light-receiving element c outputs a signal when light is being received, and the other light-receiving element c' outputs a signal when not receiving light, so by detecting these signals, T
It is detected that the feeding of the tape from reel g has been completed and the tape has reached its end.

Furthermore, as shown by the two-dot chain line in the figure, when the magnetic tape h has been completely fed out from the other tape reel g' (hereinafter referred to as the "S reel"), the other light receiving element c', that is, a transparent leader tape l' is placed between the light receiving element c' which is closer to the S reel g' and the light emitting element b.
is positioned, the light emitted from the light emitting element b and directed towards the other light receiving element c' passes through the leader tape l' and reaches the light receiving element c.
', but since the opaque part of the magnetic tape h is located between one of the light receiving elements c and the light emitting element b,
The light emitted from the light-emitting element b and directed toward the light-receiving element c is blocked by the magnetic tape h, and thereby the light from the other light-receiving element c'
The light receiving element c outputs a signal when light is being received, and the other light receiving element c outputs a signal when not receiving light.By detecting these signals, the tape is completely fed out from the S reel g' and the tape is released. It is detected that the end has been reached.

0012

However, according to such a tape end detection mechanism a, since the distance between the light emitting element b and the light receiving elements c and c' is long, the light emitted from the light emitting element b is The inner surface of the wall of the cassette case f and the tape reel g
, g' are reflected from the outer surfaces of the cassette case f and illuminated on the light-receiving elements c and c', or through external disturbance light, i.e., through the tape exits i and i formed in the cassette case f and the internal viewing window m, etc. The light incident on the cassette case f is transmitted to the light receiving elements c and c.
There is a problem that the tape end may be erroneously detected due to such light irradiation.

In particular, since tape cassettes are provided by many manufacturers, the reflectivity of the inner surface of the cassette case f, the presence or absence of protrusions, and the size, shape, and position of the window m for internal viewing are not constant. Therefore, the amount of reflected light, the amount of incident light, and the proportion of light irradiated to the light receiving elements c and c' vary, and when some types of tape cassettes are used, false detection of the tape end may occur. Even if there is no tape end, if another type of tape cassette is used, the end of the tape may be detected incorrectly.

Therefore, in order to prevent erroneous detection of the tape end caused by the above-mentioned disturbance light, etc., the light emitting element b
It has been proposed to limit the optical path between the light-receiving elements c and c'.

For example, as shown in FIG. 8, a light emitting element insertion part n having a substantially cylindrical shape and whose lower end face is opened at the bottom face of the cassette case f is formed integrally with the cassette case f, and the light emitting element insertion part n is formed integrally with the cassette case f. A relatively small light passage hole o is formed in the peripheral wall of the element insertion part n.
. There is one in which the light-receiving elements c and c' are opposed only through the passage holes o and o.

By doing this, only the light emitted from the light-emitting element b passes through the very small light passage holes o and o and is directed to the light-receiving elements c and c'. It is possible to considerably prevent the light from being reflected and irradiating the light receiving elements c and c'.

Further, a cylindrical optical path limiting member whose axial direction extends toward the light-emitting element b is arranged near the light-receiving surfaces of the light-receiving elements c and c'. There is a device in which only light coming from the vertical direction is irradiated, and by doing so, light emitted from the light emitting element b and reflected on the inner surface of the cassette case f, ambient light, etc. is transmitted to the light receiving element c. , c' can be prevented from being irradiated.

However, since the light emitting element insertion part n shown in FIG. 9 is still located with a considerable distance between the light receiving elements c and c', the light passing through the light passing holes o and Although the optical path is narrowly restricted by the light, after passing through the light passing holes o, o, the light is diffused, and a part of it is reflected by the inner surface of the cassette case f, etc., and then heads toward the light receiving elements c, c'. There is also such a light emitting element insertion part n
This alone cannot prevent the disturbance light from irradiating the light receiving elements c and c'.

In this regard, in the case where the optical path limiting member is arranged near the light receiving elements c and c', the incident angle of the light irradiated to the light receiving elements c and c' is itself limited, so that the cassette case f It is possible to considerably prevent both light reflected from the inner surface and irradiation of ambient light.

However, since such an optical path limiting member is disposed between the tape cassette d mounted on the cassette mounting section and the light receiving elements c and c', the shape of the cassette mounting section, especially the light receiving Another problem arises in that the dimensions of the elements c and c' in the arrangement direction become larger, resulting in an increase in the size of the tape player.

[0021]

[Means for Solving the Problems] Therefore, in order to solve the above-mentioned problems, the tape end detection mechanism of the present invention has a tape cassette containing a tape having a transparent leader tape and a leader trailer tape that can be detachably attached. A light-emitting element that protrudes into the cassette case when the tape cassette is installed in the cassette loading section, and a light-emitting element that is placed in a position facing the light-emitting element across the tape path in the cassette of the installed tape cassette. A light receiving element and an optical path limiting plate having a light passing hole are provided, and when a tape cassette is installed, the light path limiting plate is inserted into the inside of the cassette case at a position close to the light receiving element, and the light passing hole is inserted into the cassette case. is positioned on a straight line connecting the light emitting element and the light receiving element.

[0022]

[Operation] Therefore, in the tape end detection mechanism of the present invention, the optical path limiting plate is placed relatively close to the light receiving element, and the light passing hole is located on the straight line connecting the light emitting element and the light receiving element. Therefore, the light irradiated onto the light-receiving surface of the light-receiving element is limited to only that emitted directly from the light-emitting element toward the light-receiving element, and the remaining light, for example, emitted from the light-emitting element and emitted from the inner surface of the cassette case, etc. The reflected light and the disturbance light that entered the inside of the cassette case are blocked from the light receiving element by the part other than the light passage hole of the optical path limiting plate. Misdetection of the tape end can be reliably prevented.

Moreover, since the optical path limiting plate is provided in the cassette mounting section along with the light emitting element and the light receiving element, the positional relationship between them is always maintained constant and with high precision regardless of the tape cassette used. Furthermore, since the optical path limiting plate is disposed inside the tape cassette mounted in the cassette mounting section, the shape of the cassette mounting section does not become large.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the tape end detection mechanism of the present invention will be explained below according to the embodiments shown in the accompanying drawings.

The illustrated embodiment is based on a rotary head type audio tape player (hereinafter referred to as "R-DAT").
” he says. ) This is applied to the tape end detection mechanism in 1.

2 is a tape cassette used for R-DAT1.

The tape cassette 2 includes a cassette case 3 having a relatively thin box shape that is approximately rectangular when viewed from the thickness direction, a front cover 4 and a shutter 5 supported by the cassette case 3, and a front cover 4 and a shutter 5 of the cassette case 3. It consists of two tape reels 6, 6' housed inside and a magnetic tape 7.

The front surface 8, which forms one side in the width direction of the cassette case 3, is a tape draw-out surface, and tape outlets 9, 9 are provided at both left and right ends of the tape draw-out surface 8, and these two tape outlets A horizontally elongated substantially U-shaped tape drawer recess 10 is formed in the portion between the tape outlets 9 and 9, and a substantially cylindrical tape drawer recess 10 is formed at a position of the tape outlets 9, 9 toward the tape drawer recess 10. In-cassette tape guides 11, 11 are provided.

The front cover 4 can be placed in a closed position where the tape draw-out surface 8 is closed, that is, a position shown by a two-dot chain line in FIG. 6, and an open position where the tape draw-out recess 8 is opened, that is, in FIG. It is rotatably supported by the front end of the cassette case 3 so as to move between the positions shown by solid lines in
The tape cassette 2 is biased toward the closed position by an elastic means (not shown), and the tape cassette 2 is rotated toward the R-DAT1.
when attached to the open position.

The two tape reels 6 and 6' are rotatably housed inside the cassette case 3, and are located apart from each other in the longitudinal direction of the cassette case 3, that is, in the left and right direction. Reel stand insertion holes 6a, 6'a are formed therein, penetrating in the thickness direction.

Both ends of the magnetic tape 7 are individually fixed to the outer peripheral surfaces of the two tape reels 6 and 6' by fixing members (not shown), and are wound in a predetermined amount. After being pulled out from the cassette (referred to as an "S reel"), the tape in one cassette is wound around the guide 11, and then led out from the tape outlet 9 to the outside of the cassette case 3. From here, the tape is drawn out along the tape drawing surface 8. A path that extends, is wound around the other tape guide 11 in the cassette, is introduced into the cassette case 3 from the other tape outlet 9, and then is wound onto the other tape reel 6' (hereinafter referred to as "T reel"). is being passed through.

A portion 7a (of the magnetic tape 7) having a certain length from the end fixed to the S reel 6 (
Hereinafter, it will be referred to as "leader trailer tape." ) and a portion 7b (hereinafter referred to as "leader tape") having a certain length from the end fixed to the T reel 6' are both made of transparent tape, and the remaining portion 7c (hereinafter referred to as "leader tape") is made of transparent tape.
"Recording tape." ) is an opaque tape with a magnetic layer formed on one side, and the length of the leader tape 7b and leader trailer tape 7a is the length between the tape reels 6, 6' and the tape outlets 9, 9. The length is approximately twice the distance.

In the peripheral wall of the cassette case 3, portions 12, 12 located at both left and right ends of the tape pull-out recess 10 are provided with notches 1 whose one ends reach the tape guides 11, 11 in the cassette.
2a, 12a are formed, and rectangular holes 13a, 13a are formed at positions of the peripheral wall near the front ends of the left and right side walls 13, 13 of the cassette case 3, at positions substantially opposite to the notches 12a, 12a. has been done.

Note that these notches 12a, 12a and hole 13
13a and 13a are for emitting light from a light emitting element, which will be described later, projected into the tape drawer recess 10 to the side of the cassette case 3.

A reel stand insertion hole (not shown) is formed in the bottom plate 14 of the cassette case 3 at a position corresponding to the tape reels 6, 6', and the shutter 5 also has two similar reel stand insertion holes (not shown). is formed.

[0036]The shutter 5 is connected to the cassette case 3.
The tape cassette 2 is supported so that it can move forward and backward within a certain range while overlapping the bottom surface of the tape cassette 2, and when the tape cassette 2 is not attached to the R-DAT 1, the reel base insertion hole is inserted into the cassette. The tape cassette 2 is held in a closed position that does not match the reel base insertion hole of the case 3, that is, the position shown by the two-dot chain line in FIG. When installed in the cassette case 3, the reel stand insertion hole
is moved to the open position that coincides with the reel base insertion hole.

Reference numeral 15 denotes an elongated window formed in the top plate 16 of the cassette case 3. The window 15 is covered with a transparent plate 17, and the inside of the cassette case 3 cannot be seen through the window 15. is now possible.

Reference numerals 11a and 11a are positioning holes formed in the axes of the tape guides 11 and 11 in the cassette, and are opened in the bottom surface of the cassette case 3.

Reference numeral 18 denotes a cassette mounting section of the R-DAT 1, and the tape cassette 2 is detachably mounted to this cassette mounting section 18.

Reference numeral 19 denotes a mechanical chassis forming the base of the cassette mounting section 18.

Reference numerals 20 and 20' denote reel stands, and these reel stands 20 and 20' are attached to the rear end of the mechanical chassis 19 (the upward direction in FIG. 1 is the front side, and the downward direction is the rear side). (In addition, in the figure, the direction to the left is the left side, and the direction to the right is the right side. In the following explanation, directions will be referred to in this direction.) , and are arranged apart from each other in the left-right direction, and one of them is selectively rotated by a reel stand driving means (not shown).

Reference numerals 21 and 21 designate cassette positioning pins that are erected at positions close to the front end of the mechanical chassis 19 near both left and right ends, and flanges 21a are formed at the intermediate portions in the height direction. In addition, most of the portions 21b, 21b above the flanges 21a, 21a have a substantially conical shape.

The installation of the tape cassette 2 into the cassette installation section 18 is carried out by inserting the tape cassette 2 into a cassette holder (not shown) supported by the mechanical chassis 19 so as to be able to rotate approximately vertically. This is done by moving the

That is, when the cassette holder into which the tape cassette 2 is inserted is moved downward, the tape cassette 2
The rear end of the cassette case 3 is placed on the rear end of the mechanical chassis 19 which is slightly higher than the rest of the cassette case 3, and the positioning hole 11a formed in the cassette case 3
, 11a are the conical portions 2 of the cassette positioning pins 21, 21.
1b and 21b are inserted, and the positioning hole 11a
, 11a are the cassette positioning pins 21, 21.
The tape cassette 2 is placed on the flanges 21a, 21a of the tape cassette 2, so that the tape cassette 2 is mounted on the cassette mounting portion 18 with its horizontal and vertical positions being defined.

[0045] Then, the shutter 5 of the tape cassette 2
is moved to the open position when the tape cassette 2 is inserted into the cassette holder, and when the tape cassette 2 is installed in the cassette mounting section 18, the front lid 4 is fixed to the mechanical chassis 19. The raised member moves the reel stands 20, 20 to the open position (see FIG. 5), and the reel stands 20, 20 are engaged in the reel stand insertion holes 6a, 6'a of the two tape reels 6, 6', respectively. The reel stand 20 and the S reel 6 are coupled so that the other reel stand 20' and the T reel 6' rotate integrally, respectively.

22 is a head drum, and the head drum 22 is connected to a lower drum 22 fixed to the mechanical chassis 19.
a, an upper drum 22b rotatably supported by the lower drum 22a, and two rotating magnetic heads 22c, 22c (only one is shown in the drawing), which rotate integrally with the upper drum 22b. It protrudes upward from approximately the center of the front end of the mechanical chassis 19, and is arranged in an attitude slightly tilted to the left.

Reference numerals 23 and 23' designate loading blocks for tape loading, which are provided so as to move along guide grooves 19a and 19a formed on substantially left and right sides of the head drum 22 in the mechanical chassis 19; Each has a pair of vertical guide posts 24 and an inclined guide post 25.

Reference numerals 26 and 26' denote fridging guides, which are erected at positions near the rotation ends of the rotation levers 27 and 27, which are rotatably supported by the cassette positioning pins 21 and 21.

28 and 28' are tension rollers rotatably supported by the mechanical chassis 19, and 29 and 29' are rotating ends of rotating arms (not shown) that are rotatably supported by the mechanical chassis 19 in the horizontal direction. This is a tenregipin that was erected in the area.

[0050] These loading blocks 23
, 23', the fridging guides 26, 26', and the tension pins 29, 29' are in their initial positions shown by solid lines in FIG. When installed in the cassette installation section 18, the tape cassette 2
In other words, it is located in the tape drawer recess 10 of
It is located inside the portion of the magnetic tape 7 that is located along the tape pull-out surface 8 .

When tape loading is performed from this state, the loading blocks 23, 23', the fridging guides 26, 26', and the tension pins 29, 29' are moved toward the positions indicated by the two-dot chain lines in FIG. 1, respectively.

That is, loading blocks 23, 23'
are moved to positions corresponding to the front ends of the guide grooves 19a, 19a, and are positioned close to the head drum 22 from the left front and right front respectively, and the fridashi guides 26,
26' are respectively located immediately in front of the tape outlets 9, 9 of the cassette case 3, and ten leg pins 29,
The tension rollers 29' are brought into elastic contact with the outer circumferential surfaces of the tension rollers 28 and 28', respectively, from substantially rearward.

The magnetic tape 7 is then pulled out from the cassette case 3 by a predetermined amount and passed through the path shown by the two-dot chain line in FIG. It is wrapped spirally at the wrapping angle.

The magnetic tape 7 is running in this state, and the signals recorded on the magnetic tape 7 can be read by rotating the upper drum 22b of the head drum 22 while the magnetic tape 7 is running. The recording surface of the magnetic tape 7 is scanned by the rotating magnetic heads 22c, 22c.

The magnetic tape 7 is run by rotating the reel stand 20 or 20' to rotate the T reel 6' or S reel 6 in the tape winding direction. Depending on the direction of travel, one tension roller 28 and balance pin 29 or the other tension roller 28' and balance pin 29'
This gives an appropriate amount of back tension.

30 is a tape end detection mechanism provided in the cassette mounting section 18, and the tape end detection mechanism 3
0 is a lighthouse 32 having a light emitting element 31 and a light receiving element 33
, 33', two light receiving sections 34, 34',
and an optical path limiting member 35.

36 is a circuit board, and mechanical chassis 19
The pillars 37, 37, .
・It is fixed to the lower end surface of the screws 38, 38, . . .

The lighthouse 32 has a base 39 having a substantially cylindrical shape.
, a light emitting section 40 made of transparent synthetic resin positioned above the base 39, two leads 41, 41 protruding downward from the light emitting section 40, and a portion remaining on the light emitting section 40. It consists of a light-emitting element 31, for example, a light-emitting diode 31, which is provided in an embedded manner, and the upper ends of the leads 41, 41 are connected to the light-emitting element 31, and most of the remaining parts are penetrated through the base 39 in an embedded manner. ing.

The lighthouse 32 is provided such that the lower ends of the leads 41, 41 protrude upward from the circuit board 36 by being soldered to the circuits on the circuit board 36. A portion above the upper end of the stand 39 is inserted through an insertion hole 19b formed in a portion of the mechanical chassis 19 close to the head drum 22 from behind and protrudes upward from the mechanical chassis 19, whereby the light stand 3
2 is located between the two loading blocks 23 and 23' which are at the initial position when viewed from above.

Therefore, when the tape cassette 2 is installed in the cassette mounting part 18, the light emitting part 40 of the lighthouse 32 is located approximately halfway in the left-right direction of the tape draw-out recess 10 formed in the cassette case 3. located in position.

The light receiving sections 34, 34' include relatively small rectangular flat plate-shaped light receiving element holding sections 42, 42, and a light receiving section supported in an embedded manner with a portion left in the light receiving element holding sections 42, 42. Elements 33, 33', for example phototransistor 33
, 33', and two leads 43, 43, .
, 33', and the light-receiving surfaces of the light-receiving elements 33, 33' are exposed on one side surface in the thickness direction of the light-receiving element holding parts 42, 42.

The light receiving sections 34, 34' are arranged such that the light receiving surfaces of the light receiving elements 33, 33' face each other, and the lower ends of the leads 43, 43, . . . are soldered to the circuit on the circuit board 36. It is provided so as to protrude upward from the circuit board 36 by being attached thereto.

When the tape cassette 2 is mounted on the cassette mounting section 18, the light receiving surfaces of the light receiving elements 33, 33' of these light receiving sections 34, 34' are connected to the holes 13a, 13a of the cassette case 3, respectively. They are provided at separate opposing positions.

The optical path limiting member 35 includes a rear wall 44 that is long in the left-right direction, an upper wall 45 that projects horizontally forward from the upper edge of the rear wall 44, and a top wall 45 that extends forward from both left and right edges of the rear wall 44. Side walls 46, 46 projecting from the rear wall 44, and a mounting piece 47 projecting downward from the center of the lower edge of the rear wall 44 are integrally formed of a metal plate. The side walls 46, 46 are provided with relatively small, approximately rectangular light passage holes 4.
6a and 46a are formed.

The length of the rear wall 44 in the left-right direction is slightly shorter than the length of the tape draw-out recess 10 of the tape cassette 2 in the left-right direction.

The optical path limiting member 35 is arranged at a position near the head drum 22 on the upper surface of the mechanical chassis 19 by fixing its mounting piece 47 to the mechanical chassis 19 with screws 48 , 48 .

The lighthouse 32 is located at the center in the left-right direction inside the optical path limiting member 35, and
The light passing hole 46a on the left side of the optical path limiting member 35 is connected to the light emitting element 3.
1 and the left light receiving element 33, and the right light passing hole 46a connects the light emitting element 31 and the right light receiving element 3.
3'.

[0068] In the initial state, the loading blocks 23, 23', ten leg pins 29, 29'
is also located inside this optical path limiting member 35.

Therefore, when the tape cassette 2 is installed in the cassette mounting section 18, the optical path limiting member 35 is relatively inserted into the tape drawing recess 10 of the cassette case 3, and the light passing holes 46a, 46a are inserted into the cassette case 3. The notches 12a, 12a formed in the peripheral wall 12 of the case 3 are closely opposed to each other.

When the tape cassette 2 is installed in the cassette mounting section 18, the left light receiving element 33 connects to the left hole 13a of the cassette case 3 and the left side of the tape path in the cassette of the magnetic tape 7, that is, It faces the light emitting element 31 through the part between the S reel 6 and the tape outlet 9 on the left side, the notch 12a on the left side, and the light passage hole 46a on the left side of the optical path limiting member 35, and the light receiving element 33' on the right side faces the cassette. The hole 13a on the right side of the case 3, the right part of the tape path in the cassette of the magnetic tape 7, that is, the part between the T reel 6' and the tape outlet 9 on the right side, the notch 12a on the right side, and the right side of the optical path limiting member 35. It faces the light emitting element 31 through the light passing hole 46a.

Incidentally, since the side walls 46, 46 of the optical path limiting member 35 are close to the notches 12a, 12a of the cassette case 3, the light passing holes 46a formed in these side walls 46, 46
, 46a is the anti-light receiving element 33 on the tape path inside the cassette.
, 33' side.

The light emitted from the light emitting element 31 and passing through the light passing holes 46a, 46a travels separately toward the light receiving elements 33, 33', and these lights pass through the leader tape 7b in the tape path in the cassette. Alternatively, when the leader-trailer tape 7a is positioned, the light passes through it and is irradiated onto the light receiving element 33 or 33'.

Then, the magnetic tape 7 from the T reel 6'
In the state in which feeding has been completed (FIGS. 1, 4, and 6 show this state), the leader tape 7b is positioned in the tape path in the right cassette, and the tape path in the left cassette is unrecorded. Since the tape 7c is positioned, the light 49 that comes out from the light emitting element 31 and passes through the left light passage hole 46a
is blocked by the recording tape 7c and does not irradiate the light receiving element 33 on the left side, but the light 49' that has passed through the light passage hole 46a on the right side passes through the leader tape 7b and is irradiated onto the light receiving element 33' on the right side. be done. Therefore, in this state, the light receiving element 33 on the left side outputs a signal when not receiving light, and the light receiving element 33' on the right side outputs a signal when receiving light.
By detecting these signals, it is detected that the feeding of the tape from the T-reel 6' has been completed and the tape has come to an end.

When the magnetic tape 7 is completely fed out from the S reel 6, the leader trailer tape 7a is placed in the tape path in the left cassette, and the recording tape 7c is placed in the tape path in the right cassette. So,
Light 49' that comes out of the light emitting element 31 and passes through the right light passage hole 46a is blocked by the recording tape 7c and does not irradiate the right light receiving element 33';
The light 49 that has passed through a passes through the leader-trailer tape 7a and is irradiated onto the left light receiving element 33. Therefore, in this state, the light-receiving element 33' on the right side outputs a signal when not receiving light, and the light-receiving element 33 on the left side outputs a signal when receiving light, so by detecting these signals, S
It is detected that the feeding of the tape from the reel 6 is completed and the tape end has been reached.

Then, as described above, the optical path limiting member 3
Since the light passing holes 46a and 46a of No. 5 are located close to the tape path in the cassette, they are also relatively close to the light receiving elements 33 and 33'. The light irradiated onto the surface is transmitted to the light receiving element 33.
, 33' and the light emitting element 31. That is, among the light directed from the tape drawer recess 10 to the light receiving elements 33, 33', light other than the light that comes out from the light emitting element 31 and travels on the straight line, for example, the light emitted from the light emitting element 31.
After being emitted from the mechanical chassis 19 and the lower surface of the upper wall 45 of the optical path limiting member 35, it is reflected by the notches 12a and 1.
Light passing through 2a, light entering the tape drawing recess 10 from the outside and passing through the notches 12a, 12a, etc. are blocked by the side walls 46, 46 of the optical path limiting member 35.

[0076] Thus, the light irradiated onto the light receiving elements 33, 33' is directly transmitted from the light emitting element 31 to the light receiving elements 33, 33'.
The tape end is always detected correctly because it is limited to only the light that travels toward the tape and no external disturbance light is irradiated.

Furthermore, as described above, the lighthouse 32 is always covered by the optical path restricting member 35, and furthermore, in the initial state, the loading blocks 23, 23' and the balance pins 29, 29' are inside the optical path restricting member 35. Therefore, if the tape cassette 2 is misaligned for some reason when it is installed in the cassette mounting section 18, the cassette case 3 will come into contact with the optical path restricting member 35 and will be prevented from moving downward. As a result, the lighthouse 32, loading blocks 23, 23' and ten leg pin 29
, 29' are prevented from being damaged, and since the cassette case 3 only comes into contact with the flat upper wall 45 of the optical path limiting member 35, this can also be prevented from being damaged.

Furthermore, the presence of such an optical path limiting member 35 makes it possible to make the appearance of the cassette mounting section 18 neat when it is opened.

[0079]

Effects of the Invention As is clear from the above description, the tape end detection mechanism of the present invention can be used when a tape cassette containing a tape having a transparent leader tape and a leader trailer tape is installed in the cassette loading section. A light emitting element projected into the cassette case, a light receiving element disposed at a position facing the light emitting element across the tape path in the cassette of the attached tape cassette, and an optical path limiting plate having a light passage hole. The optical path limiting plate is inserted into the cassette case at a position close to the light receiving element when the tape cassette is mounted, and the light passage hole is located on a straight line connecting the light emitting element and the light receiving element. It is characterized by

Therefore, in the tape end detection mechanism of the present invention, the optical path limiting plate is located relatively close to the light receiving element, and the light passing hole is located on the straight line connecting the light emitting element and the light receiving element. Therefore, the light irradiated onto the light-receiving surface of the light-receiving element is limited to only that emitted directly from the light-emitting element toward the light-receiving element, and the remaining light, for example, emitted from the light-emitting element and emitted from the inner surface of the cassette case, etc. The reflected light and the disturbance light that entered the inside of the cassette case are blocked from the light receiving element by the part other than the light passage hole of the optical path limiting plate. It is possible to reliably prevent false detection of tape end, and
Since the optical path limiting plate is provided in the cassette mounting part along with the light emitting element and the light receiving element, the positional relationship between them is always maintained constant and with high precision regardless of the tape cassette used. Since the plate is placed inside the tape cassette mounted in the cassette mounting section, the shape of the cassette mounting section does not need to be enlarged.

In the above embodiment, the optical path restricting plate is formed as a part of the optical path restricting member having an upper wall substantially parallel to the mechanical chassis, and such an optical path restricting member is inserted into the tape draw-out recess of the tape cassette. When the tape cassette is attached to and removed from the cassette mounting section, the moving member for drawing out the tape is positioned under the upper wall of the optical path limiting member. By doing so, it is possible to protect the tape drawer member and the like, and it is also possible to improve the appearance when the cassette mounting section is opened.

Further, in the above embodiment, the optical path limiting plate is formed as an independent component, but it may be formed as a part of the mechanical chassis or other member.

[0083] In addition, the shapes of the members shown in the above embodiments are merely examples of embodiments of the present invention, and the technical scope of the present invention may be limited by these. Not to be construed.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an example of a tape player to which a tape end detection mechanism of the present invention is applied.

FIG. 2 is an enlarged perspective view showing the main parts of the tape player.

FIG. 3 is an enlarged horizontal sectional view of a main part showing a part of the tape cassette mounted on the cassette mounting section of the tape player and a tape end detection mechanism.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG. 1;

FIG. 5 is an enlarged sectional view taken along line V-V in FIG. 1;

FIG. 6 is a perspective view showing an example of a tape cassette.

FIG. 7 is an enlarged perspective view showing a tape reel and a portion of the magnetic tape.

FIG. 8 is a partially cutaway plan view showing an example of a conventional tape end detection mechanism.

FIG. 9 is a horizontal sectional view showing another example of a conventional tape end detection mechanism.

[Explanation of symbols]

2 Tape cassette 3. Cassette case 7 Tape 7a Leader trailer tape 7b Leader tape 18 Cassette mounting part 30 Tape end detection mechanism 31 Light emitting element 33 Photo receiving element 33' Photo-receiving element 46 Optical path limiting plate 46a Light passing hole

Claims (1)

[Claims] Claim 1: A light emitting element that protrudes into a cassette case when a tape cassette containing a tape having a transparent leader tape and a leader trailer tape is mounted in a cassette mounting section, and a cassette of the mounted tape cassette. It includes a light receiving element disposed at a position facing the light emitting element across the inner tape path, and an optical path restricting plate having a light passage hole, and the optical path restricting plate is arranged inside the cassette case when the tape cassette is installed. What is claimed is: 1. A tape end detection mechanism, wherein the tape end detection mechanism is inserted at a position close to a light receiving element, and a light passage hole thereof is located on a straight line connecting a light emitting element and a light receiving element.