Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
2000-09-28
2003-12-16
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C369S112050
Reexamination Certificate
active
06664998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a compound optical unit which is a light generating and receiving unit to be preferably used in an optical apparatus such as an optical pickup for applying light beams to an optical disk and receiving the light beams returned from the optical disk for reading from and writing on the optical disk.
2. Description of the Related Art
A compound optical unit is known which is a light generating and receiving unit for applying light beams to an optical disk and receiving the light beams from the optical disk for reading from and writing on the optical disk.
The optical unit is mounted in an optical pickup apparatus which is used for writing data on optical disks, such as a CD (compact disk), a CD-R (compact disk, recordable), and a DVD (“digital versatile disk” or “digital video disk”), and for reading data recorded on the optical disks.
Recently, a DVD device has been introduced on the market, the DVD device being for reading from and writing on DVDs which are optical disks having data densities higher than those of CDs. The DVD device is required to be compatible with a CD (including CD-R) device. Therefore, the DVD device must be provided with laser light sources having two different wavelengths, that is, a shorter, wavelength laser light source (650 nm band) for a DVD and a longer wavelength laser light source (780 nm band) for the reading from and writing on a CD-R which cannot be read by the laser source of the 650 nm band.
FIG. 18
is a plan view of an optical pickup apparatus
20
provided with known optical units
4
and
8
. The optical pickup apparatus
20
includes the optical unit
4
for a DVD
17
which is a high density optical disk, the optical unit
8
for a CD
18
which is a low density optical disk, a beam splitter
10
for guiding the laser beams, which are emitted by the optical units
4
and
8
and have different wavelengths from each other, along the same optical axis, a wavelength filter
15
serving as an aperture diaphragm for controlling the diameters of light fluxes of the laser beams in accordance with the wavelength of the laser beams, an objective lens
16
, and a carriage
20
for disposing the components at predetermined positions, thereby reading from the DVD
17
and the CD
18
.
Each component is described in detail as follows.
The optical unit
4
includes a light source
2
for generating laser beams for a DVD (wavelength in the 650 nm band), a light receiving device
3
for receiving the laser beams reflected from the DVD
17
, a substrate
4
a
provided with the light source
2
and the light receiving device
3
, a side wall
4
b
fixed to the substrate
4
a
so as to cover the light source
2
and the light receiving device
3
, an emission part
4
d
which is an opening formed in the side wall
4
b
, and an optical device
5
of a light transmitting material such as glass affixed so as to cover the emission part
4
d
. The light source
2
is fixed to the substrate
4
a
so as to oppose the optical device
5
. The light receiving device
3
is formed adjacent to the light source
2
on the substrate
4
a
. By a diffraction lattice
5
a
formed on the optical device
5
, the laser beams emitted by the light source
2
and reflected from the DVD
17
(returning light) are led to a predetermined position on the light receiving device
3
. The optical device
5
is positioned by a given reference optical system so that the beams diffracted by the diffraction lattice
5
a
are led to the predetermined position on the light receiving device
3
, then the optical device
5
is fixed to the emission part
4
d.
The optical unit
8
includes a light source
6
for generating laser beams for a CD (wavelength in the 780 nm band), a light receiving device
7
for receiving the laser beams reflected from the CD
18
, a substrate
8
a
provided with the light source
6
and the light receiving device
7
, a side wall
8
b
fixed to the substrate
8
a
so as to cover the light source
6
and the light receiving device
7
, an emission part
8
d
which is an opening formed in the side wall
8
b
, and an optical device
9
of a light transmitting material such as glass affixed so as to cover the emission part
8
d
. The light source
6
is fixed to the substrate
8
a
so as to oppose the optical device
9
. The light receiving device
7
is formed adjacent to the light source
6
on the substrate
8
a
. By a diffraction lattice
9
a
formed on the optical device
9
, the laser beams emitted by the light source
6
and reflected from the CD
18
(returning light) are led to a predetermined position on the light receiving device
7
. The optical device
9
is provided with a beam forming part
9
b
, which is a diffraction lattice, for tracking control by a three-beam method. The optical device
9
is positioned by a given reference optical system so that the beams diffracted by the diffraction lattice
9
a
are led to the predetermined position on the light receiving device
7
, then the optical device
9
is fixed to the emission part
8
d.
The beam splitter
10
guides the laser beams from the light source
2
and the light source
6
onto the optical disks
17
and
18
. The beam splitter
10
includes two triangular prisms connected to each other so as to form a rectangular parallelepiped. An optical film (dichroic film) having wavelength-selection function is coated at the interface of the two prisms. The dichroic film transmits laser beams for a CD and reflects those for a DVD, and the efficiency in use of the laser beams from the light sources
2
and
6
can be effectively designed.
The wavelength filter
15
transmits the laser beams emitted by the light source
2
, and reflects or absorbs the laser beams emitted by the light source
6
. The wavelength filter
15
controls the diameters of light fluxes of the laser beams emitted by the light sources
2
and
6
. With this arrangement, aberration is made minimized when the laser beams emitted by the light sources
2
and
6
are condensed by the objective lens
16
and a spot of the condensed laser beams is applied to the DVD
17
or the CD
18
.
The optical units
4
and
8
are disposed and operates when reading from optical disks which are the DVD
17
and the CD
18
, as described below.
The optical units
4
and
8
are disposed substantially at an angle of 90 degrees with respect to each other with the beam splitter
10
therebetween. The optical unit
8
is disposed substantially in parallel to an optical axis between the wavelength filter
15
and the objective lens
16
, and the optical unit
4
is disposed substantially perpendicular to the optical axis between the wavelength filter
15
and the objective lens
16
.
When reading from the DVD
17
, the laser beams having wavelengths of 635 to 650 nm and emitted by the light source
2
are applied to the beam splitter
10
through the emission part
4
d
and the diffraction lattice
5
a
of the optical unit
4
. The laser beams applied to the beam splitter
10
are reflected and emitted thereby substantially at an angle of 90 degrees with respect to the incident optical axis of the laser beams, and are applied to the wavelength filter
15
disposed adjacent to the beam splitter
10
. The light flux of the laser beams from the light source
2
for DVDs is transmitted by the wavelength filter
15
without being significantly restricted. The laser beams transmitted by the wavelength filter
15
are applied to the objective lens
16
and are focused on the data recording surface of the DVD
17
by a condensing effect of the objective lens
16
.
The laser beams reflected from the DVD
17
are transmitted by the objective lens
16
and the wavelength filter
15
, are reflected by the beam splitter
10
, the optical axis thereof being bent toward the optical unit
4
, and are applied to the diffraction lattice
5
a
. The laser beams are diffracted by the diffraction lattice
5
a
and are applied to a light receiving element of the light receiving device
3
. T
Kyoya Shoichi
Yamashita Tatsumaro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Pham Hai
LandOfFree
Compound optical device, compound optical unit including the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Compound optical device, compound optical unit including the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compound optical device, compound optical unit including the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3180638