JPS6321170B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical reading method and apparatus, and in particular to an optical reading apparatus such as a facsimile transmitter that scans a light beam and receives scattered light from an object to read information. The present invention relates to an optical reading method and device used in an apparatus.

The light beam scanning means in the conventional optical reading method is one using a rotating polygon mirror or a galvano mirror.
A combination of dimensional scanning and one-dimensional movement of the scanned object was used.

However, the scanning speed of this method is slow;
Another disadvantage is that the light-receiving system becomes complicated, such as requiring the use of a photodetector that is elongated in the scanning direction in order to receive the scattered light. Recently POS system (point of sale)
In order to facilitate light reception, barcode reading devices used in methods are beginning to be adopted. In principle, the light beam scanning method using a hologram scanner scans light by moving a holographically manufactured lens, so that scattered light can be easily received by the hologram scanner's own lens action.

However, when trying to use the optical beam scanning method using a hologram scanner for an optical reading device such as a facsimile transmitter, scanning using a hologram scanner alone does not provide enough resolution points and requires one-dimensional movement of the scanned object. , only low scanning speeds can be obtained.

The purpose of this invention is to eliminate the above-mentioned drawbacks,
The object of the present invention is to provide a high-speed optical reading method and mounting with a large number of resolution points. Another object of the present invention is to provide a method and apparatus for optically reading information on a large screen that does not require movement of the object to be scanned.

The optical reading method of the present invention scans a hologram using a light beam that is narrow in the scanning direction of a hologram scanner (hereinafter referred to as the main scanning direction) and focused in a direction perpendicular to the main scanning direction (hereinafter referred to as the sub-scanning direction). The object to be scanned is scanned through the scanner, and the scattered light from the object to be scanned is diffracted and imaged by a hologram that is applied to the scanning of the light beam in the hologram scanner, thereby simultaneously reading a plurality of pieces of information in the sub-scanning direction. The method of this invention utilizes the fact that the hologram scanner is equivalent to a lens, and since the positional relationship between the imaging point and the scanning point is uniquely determined, the position of the imaging point does not change, and light detection It becomes easier to install the equipment.

Various types of optical reading devices are conceivable for realizing the method of this invention, but in this invention, the spatial frequency of interference fringes is measured on a disk rotating around the center in a direction corresponding to the radial direction of this disk. A hologram disk in which multiple different holograms are arranged circumferentially, and a light beam that is arranged to illuminate the hologram disk and has a convergence point that is thin in the main scanning direction and thick in the sub-scanning direction is generated. A plurality of detection elements detect the light that is diffracted and imaged by the hologram participating in the light scanning on the hologram disk, out of the scattered light from the scanned object that is scanned by the diffracted light from the hologram disk. The method of the present invention is realized by using an optical reading device consisting of a detector that detects the image.

Hereinafter, the optical reading method and optical reading device of the present invention will be explained together with examples. Note that the optical reading method will be explained based on the operation of the optical reading device.

The figure is a schematic diagram showing an embodiment of an optical reading device of the present invention. In this embodiment, the light beam generator is composed of a laser 1 and a beam converter made of a cylindrical lens installed on the output end side of the laser 1, and the light beam from the laser 1 is transmitted to the beam converter 2. The beam diameter ratio of the vertical and horizontal beams can be changed. The hologram disk 4 is installed at a position where it is hit by the light beam from the light beam generator so as to be rotatable about an axis passing through the center of the disk. This hologram disk 4 is
A plurality of holograms having different spatial frequencies of interference fringes in the diameter direction are arranged on the disk in the circumferential direction, and the hologram disk 4
Parallel scanning of the number of scanning lines equal to the number of holograms is performed only by rotation of . A perforated mirror 3 is installed between the light beam generator and the hologram disk 4. This perforated mirror 3 receives the incident light beam from the light beam generator to the hologram disk 4, and
The light beam diffracted by the hologram disk 4 (the diffracted light from the hologram participating in the light beam scanning among the holograms constituting the hologram disk 4) is separated from the scattered light from the object to be scanned, and the It is provided to facilitate installation. Therefore, as long as it has an optical path separation function, other than the perforated mirror 3, such as a half mirror, a prism, or an optical IC, can have the same effect as in this embodiment. A photodetector is installed at a position 9 where the light beam reflected by the perforated mirror 3 forms an image. In this embodiment, a one-dimensional image sensor is used as a photodetector. Any sensor other than a one-dimensional image sensor may be used as long as it can detect multiple pieces of information simultaneously. For example, a photodiode array or a plurality of single photodiodes arranged in a row may be used, which is considered to be the best method for manufacturing the device. Furthermore, instead of installing a photodetector at the imaging point 9, the image at the imaging point 9 is transmitted through an optical fiber 11 and guided to the photodetector 12, thereby making the photodetector free from electromagnetic induction noise. It has the advantage of being able to be installed in a small space.

In the optical reading device having the above structure, the light beam from the light beam generator passes through the hole in the perforated mirror 3 and is irradiated onto the hologram disk 4 . The light beam irradiated onto the hologram disk 4 becomes diffracted light 5 and scans a scanning surface 6 on the object to be scanned.
The shape of the light beam on the scanning surface 6 is narrow in the main scanning direction and wide in the sub-scanning direction, as shown in the figure. Since the beam diameter in the sub-scanning direction is large, information in the sub-scanning direction can be obtained simultaneously, and the entire scanning surface 6 can be scanned with a small number of scanning lines. Since each hologram constituting the hologram disk 4 has a different spatial frequency in the disk diameter direction of interference fringes, a diffracted light beam 5 is generated that is shifted by the sub-scanning line width as the hologram disk 4 rotates. Therefore, one rotation of the hologram disk covers 6 scanning surfaces.
The entire surface of the image is scanned. Among the reflected and scattered light from the scanning surface 6, the scattered light 7 that reaches the hologram 8 participating in the scanning is always focused on the imaging point 9 by the lens action of the hologram, regardless of the rotation of the disk. This can be understood from the fact that the imaging point 9 and the scanning point 10 are in an image-forming relationship with respect to the hologram 8, which is equivalently a lens. Since the image of the scanning point 10 is formed at the imaging point 9, by installing a one-dimensional image sensor whose array direction is substantially in the sub-scanning direction at the imaging point 9, information on the sub-scanning direction of the object to be scanned can be obtained. can be read at the same time. Therefore,
High-speed reading is possible without forcibly increasing the rotational speed of the hologram disk.

Furthermore, as shown in the figure, by transmitting the image at the imaging point 9 through the optical fiber 11 and guiding it to the one-dimensional image sensor 12, the image sensor can be installed in a location with little electromagnetic induction noise. The number of resolution points and the reading speed of the optical reading device of the present invention are twice as many as the number of pixels of the image sensor, compared to the case where the scanning beam of the hologram scanner is scanned using a circular spot.

Therefore, according to the present invention, an optical reading device with a large number of resolution points and high speed can be obtained. The hologram disk used in this invention will be explained in more detail. The hologram disk used in this invention consists of, for example, several dozen holograms arranged on the circumference, and as the disk rotates, each hologram sequentially generates a scanning line that is shifted by the scanning line width in the sub-scanning direction. do. Such holograms are easily produced by interference between plane waves and spherical waves,
By sequentially changing the interference angle between the plane wave and the spherical wave by an amount corresponding to one scanning line width in the sub-scanning direction for each hologram, it is possible to perform scanning as described above.

In the present invention, in order to obtain high resolution, attention must be paid to the imaging performance of the hologram. Therefore, it is preferable to use a hologram (proposed in Japanese Patent Application No. 11711-1982) which is produced by interference between a diverging spherical wave and a converging spherical wave, which has excellent imaging performance.

In the above explanation, a thick beam was used only in the sub-scanning direction, but it is clear that if a thick beam is also used in the main scanning direction, a two-dimensional image can be guided to the optical fiber or photodetector array at once. be.

As described in detail above, according to the present invention, it is possible to provide an optical reading device that has a large number of resolution points, is fast, and does not require movement of the object to be scanned.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of the present invention. In the figure, 1 is a laser, 2 is a beam diameter converter, 3 is a perforated mirror, 4 is a hologram disk, 6 is a scanning surface, 8 is a hologram, 11 is an optical fiber, and 12 is a one-dimensional image sensor.

Claims (1)

[Claims] 1. An object to be scanned is scanned with a light beam that is narrow in the scanning direction of the hologram scanner (hereinafter referred to as the main scanning direction) and narrowly focused in a direction perpendicular to this scanning direction (hereinafter referred to as the sub-scanning direction). The reflected and scattered light from the scanned object is diffracted and imaged by a hologram that participates in the scanning of the light beam, and this image is read spatially at a plurality of resolutions in the sub-scanning direction. optical reading method. 2 A hologram disk in which a plurality of holograms with different spatial frequencies of interference fringes are installed circumferentially on a disk that rotates around the center, and arranged so as to illuminate the hologram disk. A light beam generator that generates a light beam having a convergence point that is narrow in the main scanning direction and wide in the sub-scanning direction; and a detector that detects an image formed by diffraction of a hologram that is scanned by the light beam on a disk at a plurality of spatial resolutions in the sub-scanning direction.