JPH11224445A - Recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the erroneous operation in the detection of the tape end in the case of using a miniature cassette. SOLUTION: By arranging a light emitting element 5 and a light receiving element 9 to the lower positions than a center line of the upper/lower parts of a reel 3 and to the upper positions than a lower side reel flange 17, the light reflected on an upper side reel flange 11 does not come up to the light receiving element due to having the excessive angle. Also, a bank-stated shield member 8 is erected so as to surround the lower part of the light emitting element, thereby the light coming toward the lower side reel flange 17 from the light emitting element 5 is interrupted. Consequently, the erroneous operation in the detection of the tape end is prevented, since almost no detecting light comes up to the light receiving element passing through the upper/lower sides of the tape 2 by reflecting from the inner surfaces of the upper/lower reel flanges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus such as a home video tape recorder. In particular, in a recording / reproducing apparatus using a small cassette such as a digital video, a recording apparatus improved so as to prevent a malfunction in detecting a transparent portion (a leader tape at the end and a trailer tape at the end) at the end of the tape. It relates to a playback device.

[0002]

2. Description of the Related Art A video tape recorder is provided with a mechanism for detecting the end of a magnetic tape stored in a loaded cassette and stopping the tape running. Usually, the end of the tape is made transparent, and when the light from the light emitting element passes through this transparent part and reaches the light receiving element, the tape end is detected. Japanese Utility Model Application Laid-Open No. 6-26085 discloses an invention relating to tape end detection in a video tape recorder. According to the same publication, a lamp case containing a light-emitting element is provided in a cassette, a light-receiving element is arranged on the side of the cassette, and a portion of the lamp case serving as a regular optical path from the light-emitting element to the light-receiving element via a tape. Is transparent, and the other parts of the lamp case are opaque. This reduces the reflection of the tape end detection light by the constituent members of the cassette, and prevents the malfunction that the reflected light reaches the light receiving element and is judged to be the tape end even though the tape is not the end (the tape is opaque). Trying to.

[0003]

However, in the same publication, no measure is taken against light reflected from the light emitting element and hitting the lower surface of the upper reel flange upward. In this specification, “down” refers to the direction of the space where the mechanism for driving the reel is present (usually on the mechanical chassis side), and “up” refers to the side opposite to the drive of the reel.
According to the analysis of the present inventors, the biggest cause of the malfunction of the tape end detection is that the reflected light on the inner surfaces of the upper and lower reel flanges wraps around the tape from above and below and reaches the light receiving element. It is due to.

The present invention has been made in view of the above problems, and has been improved in a recording / reproducing apparatus using a small cassette such as a digital video so as to prevent a malfunction in detecting a tape end. An object of the present invention is to provide a recording and reproducing device.

[0005]

In order to solve the above-mentioned problems, a recording / reproducing apparatus according to the present invention is a recording / reproducing apparatus for reading / writing a record on a tape wound around a reel and housed in a cassette. A transparent portion is provided at the end of the tape, and when the cassette is loaded, the tape has a light emission center point below the vertical center line of the reel and above the lower reel flange. A light receiving element for receiving the detection light is installed above the lower reel flange below the vertical center line of the reel, on the side of the loading portion of the cassette, and a light emitting element is applied to the cassette. Further, a member is provided that at least partially shields light from the light emitting element toward the lower reel flange.

By disposing the light emitting element and the light receiving element below the vertical center line of the reel and above the lower flange,
The reflected light from the upper reel flange is too angled and does not reach the light receiving element through the top and bottom of the tape. Moreover, no harmful light can be present on the lower reel flange due to the presence of the shielding member. Therefore,
Since almost no detection light is reflected by the inner surfaces of the upper and lower reel flanges, passes through the upper and lower portions of the tape, and reaches the light receiving element, erroneous operation of detecting the tape end can be prevented.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a configuration of a tape end detecting mechanism of a recording / reproducing apparatus (digital video tape recorder) according to an embodiment of the present invention. (A) shows the entire configuration, and (B) shows the light emitting element and the shielding member in an enlarged manner.

FIG. 1 shows the left half of the cassette 1. In the cassette 1, a left tape reel 3 and a light emitting element (LED) 5 on the right are shown. The reel 3 includes a core shaft 13, an upper reel flange 11 and a lower reel flange 17 protruding outward from upper and lower ends thereof. The core shaft 13 has a columnar shape having a central axis in the vertical direction. A recess 19 that opens downward is formed in the core shaft 13. An internal gear 15 is formed in the concave portion 19, and when the cassette 1 is loaded into the video, a drive shaft having an external gear (not shown) fits into the concave portion 19,
The reel 3 can be driven.

The light emitting element 5 is arranged at the upper end of a post 7 which stands upright from the bottom surface (mechanical chassis, not shown) of the video main body. When the cassette 1 is loaded in the video, the post 7 is inserted into the cassette 1 from the hole 1b of the cassette case bottom surface 1a. The light emitting element 5 includes a reel 3
The detection light 21 is emitted toward the tape 2 unwound or wound up from the tape. A bank-shaped shielding member 8 is provided upright at the upper end of the post 7 so as to surround the lower part of the light emitting element 5.
The shielding member 8 shields light from the light emitting element 5 toward the lower reel flange 17. This will be described later.

A light receiving element 9 is arranged on the side of the cassette 1. The light receiving element 9 faces the light emitting element 5 with the tape 2 interposed therebetween, and detects the detection light 21 emitted from the light emitting element 5. In the tape 2, only the tape end is transparent and the other portions are opaque. In a normal state, the detection light 21 passes through the tape 2 and reaches the light receiving element 9 at the tape end. Otherwise, it is blocked by the tape 2 and does not reach the light receiving element 9.

In this embodiment, the center of the light emitting element 5 and the light receiving element 9 is aligned with the vertical center line C. L. Are arranged below by h. Specifically, in the digital video example, the tape width is 6.35 mm, the reel diameter is 11.7 mm, the distance between the upper and lower inner surfaces of the reel flange is 6.7 mm, the distance between the light emitting element 5 and the light receiving element 36 is 36 mm, and the above h is preferably about 1.3 mm. .
This is to prevent light emitted obliquely upward from the light emitting element 5 and reflected by the lower surface 11a of the upper reel flange 11 from reaching the left side of the tape 2 and reaching the light receiving element 9.

Next, light emitted from the light emitting element 5 obliquely upward and reflected on the upper surface 17a of the lower reel flange 17 will be described. In this case, the detection light emitted from the light emitting element 5 is reflected by the upper surface 17a of the lower reel flange 17 and reflected on the tape 2.
The light that is likely to wrap around from below and reach the light receiving element 9 to cause the tape end detection to malfunction is the light 23 hatched in the figure. In the video of the present example, as shown in FIG. 1B, light emitted obliquely downward from the light emitting element 5 is shielded by a bank-shaped shielding member 8 to eliminate light that causes a malfunction. I have. Here, the angle of light (θ in the figure) that can pass through the shielding member 8 from the light emission center point 5a of the light emitting element 5 is:
In the above numerical examples, the angle is preferably 5.5 ° or less.

When the output of the light receiving element was actually measured for the video of this example, the output level when the opaque portion of the tape was present in the detection optical path was a noise level as low as 2.5% or less when no cassette was provided. Was. In the conventional example, a maximum of 9.
Although the value was as high as 5%, the output level was significantly lowered, and it is determined that the possibility of malfunction was substantially eliminated.

[0014]

As is apparent from the above description, according to the present invention, the light emitting element and the light receiving element are arranged below the upper and lower center lines of the reel and above the lower flange, so that the upper reel flange can be used. The reflected light will not be too angled and will not pass over and under the tape to reach the light receiving element. Also,
No harmful light can be present on the lower reel flange due to the presence of the shielding member. Therefore, almost no detection light is reflected by the inner surfaces of the upper and lower reel flanges, passes through the upper and lower portions of the tape, and reaches the light receiving element, so that erroneous operation of detecting the tape end can be prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a configuration of a tape end detecting mechanism of a recording / reproducing apparatus (digital video tape recorder) according to an embodiment of the present invention. (A) shows the entire configuration, and (B) shows the light emitting element and the shielding member in an enlarged manner.

[Explanation of symbols]

1 ... tape cassette, 1a ... cassette case bottom, 1b
... Hole, 2 ... Tape, 3 ... Reel, 5 ... Light emitting element (LE
D), 5a: emission center, 7: post, 8: shielding member, 9
... Light receiving element, 11 ... Upper reel flange, 11a ... Lower surface, 13 ... Core shaft, 15 ... Inner gear, 17 ... Lower reel flange, 17a ... Top surface, 19 ... Recess, 21 ... Detection light, 2
3: Blocking light (malfunction light)

Claims (1)

[Claims] 1. A recording / reproducing apparatus for reading / writing a record on a tape wound around a reel and housed in a cassette, wherein a transparent portion is provided at an end of the tape. At the time of loading the cassette, a light emitting element having a light emitting center point below the vertical center line of the reel and above the lower reel flange, and applying a detection light to the tape is inserted into the cassette. A light receiving element for receiving the detection light is provided below the vertical center line of the reel and above the lower reel flange, and further, at least a part of the light traveling from the light emitting element to the lower reel flange. A recording / reproducing apparatus, wherein a member for shielding is provided.