JPH0212120A - Light beam scanning device - Google Patents

Abstract

PURPOSE:To eliminate the need for a relatively expensive grid and to simplify the structure itself and reduce cost by generating a synchronizing signal with the output signal of an optical sensor, and scanning an object body according to the synchronizing signal and reading or recording an image, etc. CONSTITUTION:The optical sensor 56 is fitted to a tip part side and laser light is guided to a columnar optical guide 60 where a grid-shaped diffusion surface 52 is formed integrally by printing, etc., to obtain the synchronizing signal for image recording or reading. Consequently, no relatively expensive grid is used unlike before, the device is formed economically, and a converging rod 48 and an optical grid 52 are constituted in one body, so the light beam scanning device can be miniaturized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light beam scanning device, and more specifically, a layer required when scanning an object with a light beam to read or record an image. The present invention relates to a light beam scanning device having a mechanism for inexpensively generating synchronization signals.

[Background of the Invention] For example, in the field of printing plate-making, there are image scanning recording and reproducing systems that electrically process image information carried on a manuscript and create a film master for the purpose of streamlining work processes and improving image quality. Widely used.

This image scanning recording/reproducing system basically consists of an image reading section and an image recording section.

That is, in the image reading section, image information carried on a document that is conveyed in a sub-scanning direction is main-scanned by a photoelectric conversion element and converted into an electrical signal. Next, the image information photoelectrically converted by the image reading unit is subjected to arithmetic processing such as gradation correction and edge enhancement according to the plate-making conditions in the image recording unit, and then converted to an optical signal such as a laser beam. Recording and reproduction are performed on a record carrier made of a photosensitive material such as film.

Here, in order to accurately reproduce image information as a visible image using a light beam such as the laser light, a synchronization signal synchronized with the scanning of the light beam is required. FIG. 1 shows an outline of a mechanism for generating such a synchronization signal.

That is, in this mechanism, a synchronization signal is generated using another laser beam synchronized with a laser beam (not shown) for recording and reproducing image information on a photosensitive material or the like. Laser light source 2
The laser beam outputted from is deflected by an optical deflector 4 that vibrates at high speed in the direction of the arrow, and scans the grid 8 in the direction of the arrow via the scanning lens 6. In this case, the grid 8 is provided with a bright and dark back cover 12 in which a transparent part 10a that transmits the laser beam and a non-transparent part 10b that reflects the laser beam are alternately formed along the scanning direction of the laser beam. The laser light that has passed through the transmission section 10a enters the condensing rod 14 as a pulsed optical signal. The condensing rods 14 are arranged apart from each other along the grid 8, and a scattering surface (not shown) is formed along the longitudinal direction on the outer periphery apart from the grid 8, and a scattering surface (not shown) is formed at the end. A light sensor 16 is attached. Therefore, the laser light incident on the condensing rod 14 is reflected by the scattering surface and guided to the optical sensor 16, where it is converted into an electrical signal as a synchronization reference signal. This electrical signal is sent to the comparator 18
After being converted into 2IIt by
A PLL frequency synthesizer (not shown) disposed within 0 is used to generate a synchronization signal.

By the way, in the light beam scanning device according to the above-mentioned prior art, the grid 8 is formed by depositing chromium or the like on a light-transmissive material such as glass, and then etching it to form a grid spaced at predetermined intervals. It is formed by providing a light beam transmitting section 10a having a shape. As described above, since the manufacturing process of the grid 8 is complicated, there is a drawback that the cost of the grid 8 is considerably high. That is, as a result, the manufacturing cost of the entire optical beam scanning device in which the grid 8 is arranged increases.

Furthermore, as can be understood from FIG.
and the condensing rod 14 are arranged apart from each other. Therefore, it is pointed out that the work of adjusting the relative positions of the grid 8 and the condensing rod 14 becomes complicated, and the overall size of the light beam scanning device increases.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes a light beam scanning device that scans an object by deflecting a light beam using a light deflecting means. An optical grid-like structure consisting of a light beam transmitting part and a non-transmitting part is provided on the back surface of a condensing rod that condenses a synchronizing light beam branched from the scanning light beam onto the light detection means when irradiating the object to be scanned. By integrally forming the pattern by, for example, printing, the relatively expensive grid used in the past becomes unnecessary, making it possible to manufacture economically, simplifying the structure itself, and making it more flexible. An object of the present invention is to provide a light beam scanning device that can be miniaturized as much as possible.

[Means for achieving the object] In order to achieve the above object, the present invention provides a light beam incident surface extending in a direction substantially perpendicular to the optical axis of the light beam deflected through the light beam deflection means. a cylindrical body having a lattice-like diffusing surface extending in a direction substantially perpendicular to the optical axis on the back surface corresponding to the light beam incident surface, and having an optical sensor attached to at least one end thereof; The present invention is characterized in that it includes a light guide, generates a synchronization signal from the output signal of the optical sensor, scans the object to be scanned based on the synchronization signal, and reads or records an image or the like.

[Embodiments] Next, preferred embodiments of the light beam scanning device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2a, reference numeral 30 indicates the main body of the light beam scanning device according to this embodiment. This main body part 30 has a laser diode 32 that outputs a laser beam L1 for recording and a laser diode 34 that outputs a laser beam L2 for synchronization. The light is guided to a galvanometer mirror 40 as a light deflecting means. The galvanometer mirror 40 vibrates at high speed in the direction of the arrow, and the recording and synchronization laser beams, L2, are reflected and deflected by the galvanometer mirror 40 and transmitted to the image recording unit 44 and synchronization via the scanning lens 42 consisting of an fθ lens. The signals are respectively guided to the signal generating section 46.

The image recording section 44 consists of a drum 47 that rotates in the direction of the arrow, and a pair of nip rollers 49a and 49b that are pressed against the drum 47 via the film F on which the image is recorded. It is sub-scanned and conveyed in six directions. Incidentally, the recording laser beam guided to the image recording section 44 via the scanning lens 42 main scans the film F in the direction of arrow B.

On the other hand, the synchronizing signal generating section 46 has a structure different from that of the synchronizing signal generating section shown in FIG.

That is, the synchronization signal generating section 46 includes a condensing rod 48, and the condensing rod 48 is made of a columnar optically transparent material, preferably acrylic resin or optical glass. In this case, optical transparency means that there is substantially no material absorption loss for the wavelength of the laser light used.

The condensing rod 48 has a back surface 51b corresponding to the surface 51a on which the synchronizing laser beam L2 is incident, and a diffusing surface 52 made of, for example, a light-scattering paint film, extending in the axial direction, is arranged in a grid pattern. It is provided.

A light receiving surface of an optical sensor 56 is disposed to face at least one end side side surface of the light collecting rod 48, thereby forming a light guide 60.

The output signal of the optical sensor 56 is inputted via an amplifier 64 and a binarization comparator 66 having a threshold value α to a synchronization signal generation circuit 68 consisting of a PLL synthesizer to obtain a synchronization signal. Note that the lattice-shaped diffusion surface 52 is, for example,
It can also be formed by applying a white paint such as barium sulfate or white titanate, or it can be formed by a vacuum evaporation method using a chromium material, aluminum material, or the like having light reflectivity.

The light beam scanning device according to this embodiment is basically constructed as described above, and its operation and effects will be explained next.

Therefore, when the laser diode 34 is driven, the synchronization laser beam L2 output from the laser diode 34 is
is made into a parallel light beam by the collimator 38, and then enters the galvanometer mirror 40. The galvanometer mirror 40 is vibrating at high speed in the direction of the arrow, and the synchronizing laser beam L2 reflected by the galvanometer mirror 40 is transmitted via the scanning lens 42 to the incident surface 51a of the condensing rod 48 constituting the light guide 60. be guided. in this case,
As described above, the back surface 51b corresponding to the incident surface 5LH is formed with a lattice-shaped diffusing surface 52 along the scanning direction of the synchronizing laser beam L2, and the synchronizing laser beam L2 incident from the incident surface 51a. A part of the light is diffused by the diffusion surface 52 (see FIG. 2), and guided to the optical sensor 56 disposed at the end of the rear side where the light is repeatedly reflected by the inner circumferential surface of the condensing rod 48. The pulsed electric signal photoelectrically converted by the optical sensor 56 is amplified into an electric signal of a predetermined amplitude by an amplifier 64 (see FIG. 3C), and then converted into a binary signal by a binarization comparator 66 having a threshold value α. The signal is converted into a square wave signal (see Figure 3). This square wave signal is generated by the PL built in the synchronization signal generation circuit 68.
The synchronization signal (
(see FIG. 3C) is generated.

In this case, in this embodiment, the grid-like diffusing surface 52 is integrally formed with the condensing rod 48.

Therefore, the grid 8 shown in the prior art shown in FIG. 1 is not required, and the light beam scanning device can be manufactured at low cost and in a small size.

The laser diode 32 is controlled based on the synchronization signal generated as described above, and the recording laser beam L1 modulated according to the image information is output. laser diode 3
The recording laser beam L1 output from the collimator 3
After being made into a parallel light beam by 6, the light beam enters a galvanometer mirror 40. The galvanometer mirror 40 vibrates at high speed in the direction of the arrow, and the recording laser beam is reflected and deflected by the galvanometer mirror 40 and main-scans the film F in the direction of the arrow B via the scanning lens 42. On the other hand, the film F is connected to the drum 47 and the nip roller 49a.
, 49b, and is conveyed in the sub-scanning direction in the direction of arrow A. Therefore, an image is two-dimensionally formed on the film F by the recording laser beam L1.

In this embodiment, an example of a light beam scanning device for image recording is shown, but it goes without saying that the invention can be similarly applied to a light beam scanning device for image reading. In addition, in this embodiment, the light guide is configured in the shape of a regular square prism, but the shape is not limited to the shape of a regular square prism.Although the thickness in the direction toward the optical axis of the light beam is approximately constant, the light guide is It is also possible to improve the light collection efficiency of the light guide by forming the light guide into a quadrangular prism shape in which the area of one end surface is larger than the area of the other end surface to which it is not attached.

[Effects of the Invention] As described above, according to the present invention, a laser beam is attached to a columnar light guide that has an optical sensor attached to its tip side and has a grid-like diffusion surface integrally formed by printing or the like. It guides light and obtains synchronization signals for recording or reading images. For this reason,
It is possible to provide an economical light beam scanning device without using a relatively expensive grid as in the prior art. Moreover, since the condensing rod and the optical grating are integrally constructed, it is possible to reduce the size of the light beam scanning device.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
For example, making the light guide cylindrical instead of square prism, etc.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a synchronization signal generation mechanism in a light beam scanning device according to the prior art; Fig. 2a is a block diagram of the main body of a light beam scanning device according to the present invention; 3A to 3C are waveform diagrams illustrating the operation of the light beam scanning device. 30... Main body 32.34... Laser diode 36.38... Collimator 40... Galvanometer mirror

Claims (1)

[Claims] (1) Extending in a direction substantially perpendicular to the optical axis of the light beam deflected by the light beam deflection means to form a light beam entrance surface, and at the same time forming a light beam incident surface on the back surface corresponding to the light beam entrance surface. A column-shaped light guide extending in substantially orthogonal directions to form a lattice-like diffusing surface and having an optical sensor attached to at least one end side, and generating a synchronization signal based on the output signal of the optical sensor. A light beam scanning device that scans an object to be scanned and reads or records an image or the like based on the synchronization signal.