Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1999-10-27
2003-01-14
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S239000
Reexamination Certificate
active
06507355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image recording apparatus for recording images, characters, etc. onto a recording medium by using a recording laser head and, more particularly, an image recording apparatus with high reliability, which can execute a high-speed image recording onto a recording medium in a heat mode with the use of an interference type optical shutter which can withstand a high power laser light.
2. Description of the Prior Art
In the image recording apparatus for recording the images onto the recording medium, improvement in the image recording speed is always requested. In particular, in the image recording apparatus for recording the images in unit of pixel (dot) by scanning an optical spot onto the recording medium such as photosensitive material, etc., it is effective in improving the recording speed to record a plurality of dots simultaneously by irradiating a plurality of optical spots simultaneously to the recording medium.
In unexamined Patent Application Publication (JPA) Hei 2-254472, the fixedly scanning type print head has been proposed in connection with such image recording apparatus.
In Patent Application Publication (KOKAI) Hei 4-303817, Patent Application Publication (KOKAI) Hei 4-306620, etc., the optical head which can expose and record a plurality of dots simultaneously has been proposed. More particularly, the optical device (so-called optical shutter array) which has a plurality of prismatic shutter portions made of PLZT and arranged at a predetermined interval along a predetermined direction is provided, then the laser beam emitted from one or more laser light sources is shaped into the wide laser beam along the predetermined direction by the optical system, which is arranged between the laser light source and the optical shutter array, then the polarizing direction of the laser beam transmitted from the shutter portions is changed selectively by the optical shutter array, which is arranged at the beam waist position of the laser beam, then only the laser beam which is transmitted through respective shutter portions of the optical shutter array and has the predetermined polarizing direction can be irradiated onto the recording medium.
In addition, in Patent Application Publication (KOKAI) Hei 9-216417, the optical device which can control the polarization of the incident laser beam in response to the recorded images such that the energy of the incident laser beam can be utilized effectively in recording the image and which has low probability of the failure has been proposed. This optical device is constructed to comprise the light transmitting portion which is made of electro-optical material such as PLZT, etc. and whose length along the traveling direction of the incident laser beam is set constant and which has the successive shape along the predetermined direction intersecting with the incident laser beam, and a plurality of electrode pairs arranged on both sides of the optical transmitting portion to put the optical path of the incident laser beam between them and arranged at a predetermined interval along the predetermined direction.
A configuration of an optical system of an optical head employing the optical device (PLZT device) as the optical shutter is shown in
FIGS. 25A and 25B
. The optical system of the optical head is constructed to comprise a semiconductor laser
301
, a first lens (cylindrical lens)
311
, a second lens
312
, a first polarizing device
304
, an optical device (PLZT device)
305
, a second polarizing device
306
, a third lens
313
, and a fourth lens
314
.
A first optical system consisting of the first lens
311
, the second lens
312
, and the first polarizing device
304
transmits the laser beam, which is emitted from the semiconductor laser
301
, into a light transmitting portion consisting of the optical device
305
as a luminous flux which is formed wide along the predetermined direction. Then, the voltage is applied selectively to a plurality of electrode pairs of the optical device
305
by a controlling means (not shown) so as to form the image which is to be recorded on the recording medium
3
(recording member on a drum
2
). Accordingly, the polarization of the incident laser beam is controlled in response to the recorded image every luminous flux, which is transmitted via a different portion on the light transmitting portion of the optical device
305
, so that the polarization direction is rotated by 45° or 135°. Then, most of the laser beam having the polarization direction of 45° is removed from the laser beam transmitted through the optical device
305
by the second polarization device
306
. Then, the recording laser beam having the polarization direction of 135° is irradiated onto the recording medium
3
via the first optical system consisting of the third lens
313
and the fourth lens
314
.
In this while, in the image recording apparatus in the prior art, the normal power semiconductor laser is employed as the light source. The image can be recorded sufficiently practically by the normal power semiconductor laser onto the fast recording medium (photo mode), e.g., photographic film, printing lith film (the silver salt is employed as photosensitive material), etc. However, since the sensitivity is lowered by three to five digits in the transfer type recording medium (heat mode), the irradiation of the laser beam (exposure) is needed for a long time if the normal power semiconductor laser is employed. Therefore, there is the circumstance that, since a processing time from several thousand times to several hundred thousand times must be consumed in the heat mode, the normal power semiconductor laser is not practical.
For this reason, the recording medium of the heat mode is employed, it is desired to use the high output semiconductor laser as the light source. In this case, in the configuration in which the optical device (PLZT device) or the liquid crystal optical shutter (FLC) is used as the optical shutter like the image recording apparatus in the prior art, the power-tolerance property is required for the optical shutter to withstand the high power laser beam. However, even if the liquid crystal or the PLZT device absorbs merely several % of the optical energy emitted from the high output semiconductor laser, the temperature of the liquid crystal or the PLZT device is excessively increased to thus depart from the rated operating temperature. As a result, there is the circumstance that a possibility of the failure of the system is caused.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstance in the prior art, and it is an object of the present invention to provide an image recording apparatus with high reliability, which can execute a high-speed image recording onto a recording medium in a heat mode with the use of an interference type optical shutter which can withstand a high power laser light.
In order to overcome the above subject, an image recording apparatus set forth in a first aspect of the present invention, for recording images on a recording medium by modulating a light emitted from a light source by an optical modulation device, wherein the light source comprises a high power laser, and the optical modulator device is comprises a transmission type optical modulator device which optically modulates the light emitted from the light source by an optical interference effect based on an electro-mechanical operation of a flexible thin film.
In this image recording apparatus, since the transmission type optical modulation device (interference type optical shutter) in which the irradiation light from the high power laser is optically modulated by the electromechanical operation of the optical modulation device is employed, absorption of the incident light can be reduced extremely and also the high output-tolerance property against the high power laser can be enhanced rather than the configuration using the optical device and the crystal liquid shutter in the prior art. In addi
Kimura Koichi
Sasaki Yoshiharu
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