Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-08-30
2001-05-22
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C356S027000
Reexamination Certificate
active
06236039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotation speed detecting device for a recording and reproducing apparatus, and a method therefor, and in particular to a rotation detecting device for a recording and reproducing apparatus which can exactly detect a rotation speed of a rotation member which is rotated at a high or low speed, and a method therefor. More particularly, the present invention relates to a rotation detecting device for a recording and reproducing apparatus and a method therefor which can easily precisely detect a rotation speed of a reel during a high- or low-speed rotation, and which can exactly detect a rotation speed of a motor of an optical disc recording and reproducing apparatus, by forming in a series equational division method a wing unit and a space unit of a sensor detecting member which is protrusively formed in a single body at a supply reel and a take-up reel of the recording and reproducing apparatus, such as a VCR.
2. Description of the Background Art
FIG. 1
is a schematic view illustrating an inside structure of a VCR which is a general recording and reproducing apparatus.
A capstan shaft
11
rotated to play a tape is provided at one side of a drum
10
including a rotation head, and a capstan pulley
12
rotated in a single body with the capstan shaft
11
is installed at the capstan shaft
11
.
A pulley gear
13
is provided separately from the capstan pulley
12
by a predetermined distance. The pulley gear
13
is connected to the capstan pulley
12
by a belt
14
, and thus a rotation of the capstan pulley
12
is transferred thereto.
At one side of the pulley gear
13
is provided an idle gear
15
engaged with the pulley gear
13
, and moved and rotated to the right or left side in accordance with an operational mode of the recording and reproducing apparatus.
A supply side intermediate gear
16
and a take-up side intermediate gear
17
are provided at the right and left sides of the idle gear
15
, respectively, and engaged with the idle gear
15
according to a right- or left-direction movement of the idle gear
15
.
In addition, a supply reel
1
is provided to be engaged with the supply side intermediate gear
16
, and a take-up reel
2
is disposed to be engaged with the take-up side intermediate gear
17
. Accordingly, a rotation of the idle gear
15
is transferred to the supply side intermediate gear
16
or take-up side intermediate gear
17
, thereby rotating the supply reel
1
or the take-up reel
2
.
On the other hand, a rotation detecting device is provided to the recording and reproducing apparatus including the above-described components, in order to detect a rotation speed of the supply reel and the take-up reel when the tape is moved by a capstan motor. It will now be explained with reference to
FIGS. 2
to
5
.
FIG. 2
is a perspective view illustrating a detecting sensor measuring a rotation speed of the supply reel and the take-up reel for the general recording and reproducing apparatus.
FIG. 3
is a circuit view illustrating a circuit constitution of the general detecting sensor.
FIG. 4
is a perspective view illustrating a conventional sensor detecting member formed at a supply reel and a take-up reel for a general magnetic recording and reproducing apparatus.
FIG. 5
is a graph showing an operational pulse in accordance with a conventional rotation speed detecting device.
Referring to
FIGS. 2
to
5
, in the rotation detecting device detecting a rotation speed of the supply reel and the take-up reel for the general recording and reproducing apparatus, a detecting sensor
7
including a light emitting unit
8
and a light receiving unit
9
as shown in
FIG. 2
is disposed at each one side of the lower portions of the supply reel
1
and the take-up reel
2
, and a ring-shaped sensor detecting member
20
is formed in a single body at the lower surfaces of the supply reel
1
and the take-up reel
2
.
Here, a plurality of wing strips
30
and a plurality of space parts
40
which have an identical width (W
1
=W
2
) are alternately formed at the lower portion of the sensor detecting member
20
in accordance with the equational division method. The plurality of wing strips
30
and the plurality of space parts
40
are positioned between the light emitting unit
8
and the light receiving
9
of the detecting sensor
7
, rotated when the supply reel
1
or the take-up reel
2
is rotated, and passed between the light emitting unit
8
and the light receiving unit
9
of the detecting sensor
7
.
The rotation detecting device, namely the detecting sensor
7
and the sensor detecting member
20
may be provided at the supply side intermediate gear
16
and the take-up side intermediate gear
17
, respectively.
Reference mark Vcc denotes a voltage, R
1
, R
2
, R
3
denote resistances, and C
1
denotes a condenser.
The operation of the recording and reproducing apparatus including the above-described rotation detecting device, and the rotation speed detecting operation of the rotation detecting device will now be described.
When an operational command is provided to the recording and reproducing apparatus, the capstan shaft
11
is rotated. As the capstan shaft
11
is rotated, the capstan pulley
12
formed in a single body with the capstan shaft
11
is rotated.
When the capstan pulley
12
is rotated, the pulley gear
13
connected to the capstan pulley
12
by the belt
14
is rotated, and thus the idle gear
15
engaged with the pulley gear
13
is rotated. Here, the idle gear
15
is moved to the right or left side according to an initial operational command, and then rotated.
Thereafter, the idle gear
15
is moved to the right or left side, and thus selectively engaged with the supply side intermediate gear
16
or the take-up side intermediate gear
17
respectively disposed at the left and right sides thereof. As a result, the supply side intermediate gear
16
or the take-up side intermediate gear
17
is rotated, and thus the supply reel
1
or the take-up reel
2
engaged respectively with the supply side intermediate gear
16
or the take-up side intermediate gear
17
is rotated.
Accordingly, as the supply reel
1
or the take-up reel
2
is rotated, the sensor detecting member
20
formed in a single body at the lower surface of the supply reel
1
or the take-up reel
2
is rotated, and thus the plurality of wing strips
30
and the plurality of space parts
40
of the sensor detecting member
20
are alternately passed and rotated between the light emitting unit
8
and the light receiving unit
9
of the detecting sensor
8
.
Therefore, when the detecting sensor member
20
is passed and rotated through the detecting sensor
7
, if the space part
40
is passed therethrough, a light generated from the light emitting unit
8
of the detecting sensor
7
is transmitted to the light receiving unit
9
, and thus a microcomputer (not shown) disposed at a circuit unit recognizes a rotation of the supply reel
1
or the take-up reel
2
.
Since the conventional detecting sensor member
20
includes the plurality of wing strips
30
and the plurality of space parts
40
having an identical width (W
1
=W
2
) according to the equational division method, if the wing strips
30
and the space parts
40
are widely formed, and the supply reel
1
or the take-up reel
2
is rotated at a high speed, the sensor detecting member
20
can detect the rotation of the supply reel
1
or the take-up reel
2
, and transmit a data in order for the microcomputer (not shown) to recognize the rotation without an error. However, in the case of a slight rotation of {fraction (1/10)}~{fraction (1/20)}, the detecting sensor
7
can detect the rotation only when a rotation angle of the supply reel
1
or the take-up reel
2
is increased. In case the rotation angle of the supply reel
1
or the take-up reel
2
is small, the wing strip
30
or the space part
40
is positioned at the detecting sensor
7
, and thus the detecting sensor
7
is not varied.
That is t
Allen Stephone B.
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
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