JPS6232770A - Optical reader - Google Patents

Abstract

PURPOSE:To make unnecessary a mechanical movable member and to miniaturize a device and to improve the reliability and durability of the device by deflecting and scanning a laser beam passing through a light waveguide path within a fixed light transmission medium at a light deflection part. CONSTITUTION:A CPU10 supplies a driving signal to seven light emitting elements 20 through an output port 15, seven D/A converters 16 and seven driver circuits 18. The light emitting elements 20 are light sources consisting of semiconductor laser chips, etc., and the laser beams emitted from the light emitting elements 20 are light-deflected by seven light deflection elements 22, light-scanning on an original. The reflected light from the original on which the laser beams are irradiated by the seven light deflection elements 22 are guided to and detected at corresponding seven photodetecting elements provided by an optical fiber device 56. And through an amplifier 68 and a comparator 70, they are added on an input port 72, being stored within a RAM14 by the CPU10.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to optical reading devices, and more particularly to techniques for improving durability by eliminating mechanically movable parts.

2. Description of the Related Art There is an optical reading device that reads lines or dots drawn on a surface to be read based on reflected light from the surface to be read when scanning with a laser beam. Such a device generally uses a rotating mirror or the like to scan the surface to be read with a laser beam. Special Public Service 1977
The device described in Japanese Patent No. 19497 is one example, and as shown in FIG. The surface to be read 104 is scanned by being reflected by the rotating mirror 102 which is rotationally driven around the optical axis by the rotating mirror 109, and the reflected light from the surface to be read 104 is reflected by the rotating mirror 102 and the half mirror 101. After being reflected, it passes through a condensing lens 105 to the first optical sensor 10.
6 and is detected there. On the other hand, the above laser beam @
A portion of the sea 43' beam emitted from the half mirror 100 is reflected by the half mirror 101 without passing through it, and is detected by the second optical sensor 107. and,
In the signal detection circuit 108, an image formed by lines or points on the surface to be read 104, such as characters, is generated from the light detected by the first photosensor 106 using the light detected by the second photosensor 107 as a reference. , figures, codes, etc. can be read.

Problems to be Solved by the Invention However, in such conventional optical reading devices,
The deflection device for deflecting light is equipped with a rotating device such as a rotating mirror, a mechanical movable part such as a rotating drive device for rotating the device, and an optical system having a relatively large number of optical elements. However, the noise of the device is large, the device is large, and sufficient reliability and durability are not necessarily obtained.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
Its gist is that it is an optical reading device that reads lines, points, etc. drawn on a surface to be read based on reflected light from the surface to be read obtained when scanning a laser beam. 1) A solid-state optical transmission medium provided with an optical waveguide, and an optical deflection section provided on the solid-state optical transmission medium to deflect the direction of a laser beam passing through a leading waveguide in the solid-state optical transmission medium, (2) a light-receiving element for receiving the reflected light from the surface to be read; and (3) a large number of light-receiving elements that guide the reflected light to the light-receiving element. An optical fiber device comprising an optical fiber and arranged along a scanning line of a laser beam scanned on the surface to be read with the end face on the input side of the optical fiber facing the surface to be read. , to include.

Operation and Effect of the Invention In this way, the solid-state optical transmission medium provided with a leading waveguide, and the direction of the laser beam that is provided in the solid-state optical transmission medium and passes through the leading waveguide in the solid-state optical transmission medium can be deflected. The direction of the laser beam is deflected by the optical deflection action of the optical deflection element that scans the laser beam on the surface to be read. No mechanical moving parts are required, making the device smaller, more reliable and durable, and eliminating noise.

Further, the optical fibers include a large number of optical fibers and are arranged along a scanning line of a laser beam scanned onto the surface to be read with the end face of the optical fiber on the input side facing the surface to be read. Since the device guides the reflected light from the surface to be read to the light receiving device, the optical system becomes simple, and in this respect as well, the device becomes compact and highly reliable.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, CPU10. ROMI 2, and R
The AM 14 constitutes a control device for the optical reading device, and controls the intensity of the irradiated light, the deflection angle of the irradiated light, and the reading of the reflected light. The CPU 10 is connected to an output port 15.
7 D/A converters 16 and 7 driver circuits 1
A driving signal is supplied to the seven light emitting elements 20 via the respective light emitting elements 8. The light emitting element 20 is a light source composed of a semiconductor laser chip or the like, and outputs irradiation light. - The seven light deflection elements 22 arranged in parallel include the light emitting elements 20
are provided respectively, and the optical deflection element 22 is
The direction of the laser beam output from the light emitting element 20 is deflected in accordance with the voltage signal from the deflection control circuit 24 controlled by l0.

FIGS. 2 and 3 show a plane and a side view of an example of the optical deflection element 22. FIG. In the figure, the light emitting element 20 is integrally provided on the end face of a single substrate 28 having light-transmitting properties. The substrate 28 is made of an electro-optic material such as LiNb0. It is made of a single crystal plate with a thickness of about 0.5 m, and the light deflection section 38, which will be described later, is the negative side of the plate.
A two-dimensional optical waveguide 32 is provided in the portion where the optical waveguide 32 is provided.

This two-dimensional optical waveguide 32 has a refractive index larger than that of other parts of the substrate so that light is confined in a plane.For example, Ti (titanium) is
It is formed into a relatively thin layer of about several micrometers by diffusing it. Note that the two-dimensional optical waveguide 32 differs only in refractive index from other parts, and the refractive index changes continuously, so the boundaries between them are shown by broken lines.

The laser beam 50 emitted from the end face of the light emitting element 20 passes through the light collecting section 3 in the process of being guided within the two-dimensional optical waveguide 32.
6, the light beam is converged into parallel light, deflected by a light deflection section 38, and focus corrected by a light flux correction section 40.

That is, the light collecting section 36 is arranged in the plane direction of the substrate 28 and along the optical axis of the laser beam 50. By diffusing a diffusing material such as Ti in such a way that the diffusion concentration increases as it approaches the optical axis L0 in the direction perpendicular to the optical waveguide 32, the refractive index of the two-dimensional optical waveguide 32 increases as it approaches the optical axis L0. It is equipped with a convex lens function. Although the group of straight lines shown in the light converging section 36 in FIG. 2 cannot actually be seen with the naked eye, they represent the refractive index distribution, and the linear density thereof indicates the height of the refractive index. Incidentally, the light collecting section 36 may be formed of a geodesic lens or the like formed by providing a concave section on the surface of the two-dimensional optical waveguide 32.

The light deflection section 38 and the light flux correction section 40 are each constructed by disposing a large number of electrodes on the two-dimensional optical waveguide 32 with a buffer layer 42 interposed therebetween. The buffer layer 42 is made of a transparent material having a refractive index lower than that of the two-dimensional optical waveguide 32, such as SiOz, and has a thickness of about several μm, and is used to prevent absorption of light by the electrodes described later. However, it does not necessarily have to be provided.

The optical deflection section 38 is aligned with the optical axis. A pair of electrodes 44.46 located on both sides of the optical axis L between these electrodes 44.46
0 and diagonal electrodes 48.

In general, electro-optic materials have the property of changing their refractive index depending on the strength of the electric field (electro-optic effect). For example, when the substrate is LiNb0z (Y-cut crystal), the The change Δn in the refractive index of the part where the
ss·E (1) where no is the refractive index of the substrate for extraordinary light, and ro is the electro-optical constant in the plane direction of the substrate.

Distribution of the magnitude of the refractive index in the direction perpendicular to the optical axis L0,
That is, the distribution of the refractive index change Δn also changes corresponding to the distribution of the electric field E. For example, when a positive voltage is applied to the electrode 48 and a ground voltage is applied to the electrodes 44 and 46, the A-A of the optical deflection section 38
The distributions of the electric field E and the refractive index change Δn on the lines , B-B, and C-C are as shown in FIGS. 4, 5, and 6, respectively.

Therefore, the laser beam 50 traveling parallel to the optical axis L0
is bent towards the higher index of refraction due to the different refractive index it experiences.

Therefore, when the voltage signals applied from the deflection control circuit 24 between the electrode 48 and the electrodes 44 and 46 are temporally changed in a sawtooth waveform as shown in FIG. 7 or 8, In synchronization, the deflection angle θ of the laser beam 50 is changed in a sawtooth waveform. The electric field E in FIGS. 4 to 6 is shown with the downward direction in FIG. 2 being positive, and the electrode 44 is viewed from the right hand and the electrode 46 is viewed from the left hand.

Next, the light flux correcting section 40 converges the laser beam 50 deflected by passing through the light deflecting section 38 onto the scanning line 26 on the surface to be read with a spot size of an appropriate size. As shown in FIG. 2, it has a large number of three-dimensional optical waveguides 52 radially, and a series of correction electrodes 54. Although seven three-dimensional optical waveguides 52 are shown in the figure for ease of understanding, in reality there are a very large number of three-dimensional optical waveguides 52.
is provided. Furthermore, although these three-dimensional optical waveguides 52 are shown as solid lines, they simply have a high refractive index and cannot actually be seen with the naked eye.

The three-dimensional optical waveguide 52 is configured such that the refractive index becomes higher toward the center due to diffusion of Ti, etc., and the laser beam 50 propagating through the three-dimensional optical waveguide 52 is periodically converged as shown in FIG. I am made to do so.

Therefore, by selecting the length l of the three-dimensional optical waveguide 52, a laser beam spot of an appropriate size can be formed on the scanning line 26. As shown in FIG. 10, the correction electrodes 54 are, for example, electrodes 54aa and 54ab that are parallel to each other in the three-dimensional waveguide 52a.
, 54ac, and 54ad are provided for each three-dimensional optical waveguide 52. electrode 52
The electrodes aa and 52ad are spaced apart from the side edges of the three-dimensional optical waveguide 52a, and the electrodes 52ab and 52ac are located on the optical waveguide 52a with its center line interposed therebetween.

Voltages of the same potential, for example, ten potentials and one potential, are applied alternately to every other electrode 54aa, 54ab, 54ac, and 54ad, so that the center portion of the three-dimensional optical waveguide 52a has a refractive index lower than the side edge portions. It can be changed greatly. For this reason, focus correction is performed by changing the state shown in FIG. A signal for this purpose is supplied from the deflection control circuit 24 in relation to the deflection angle.As shown in FIG. To correct the focus in the vertical direction, a toroidal lens 56 is provided as necessary. In addition, other optical elements may be appropriately provided as necessary, and the laser beam 50 to be formed on the scanning line 26 If the spot size does not require much precision, the luminous flux correction section 40 may not be provided.

Returning to FIG. 1, on the surface to be read, the respective reflected lights from the areas irradiated with the laser beam 50 by the seven optical deflection elements 22 are respectively provided by seven optical fiber devices 56. The light is respectively dedicated to seven light receiving elements 60 and detected there.

That is, the optical fiber device 56 is
As shown in FIG. 4, the scanning line 26 of the laser beam 50 is provided with a large number of optical fibers 58, and is scanned onto the surface with one end surface of the optical fibers 58 facing the surface to be read. The other end is connected to the light receiving element 60. The light-receiving element 60 is composed of a phototransistor or a photodiode, and its light-receiving surface faces the multiple end faces of the other end of the optical fiber 58. In addition, the 13th
The figure is a developed view to easily show each component, and in reality, as shown in FIG. The optical fiber 58 has one end face fixed in the same direction along the exit side end face 64 of the optical deflection element 22, and the other end face fixed in position. It is fixed in a state facing the light receiving element 60. Note that 68 is an amplifier that amplifies the output signal of the light receiving element 60.

As shown in FIG. 1, the output signal from each amplifier 68 is input to a comparator 70, respectively.

A reference signal from a setting device (not shown) is supplied to the comparator 70, and the comparator 70 compares the reference signal with the output signal from the amplifier 68. If the output signal exceeds the reference signal, the comparator output is increased to that point. and reverse it. This inverted signal is sent to the CPU via input port door 2.
10 and stored in the RAM 14.

Next, the operation of the optical reading device configured as above will be explained according to the flowcharts of FIGS. 15 and 16.

First, prior to reading an image consisting of lines or dots drawn on the surface to be read, the light emitting element 20 and the light deflection element 2 are
2, and the individual outputs of the light receiving element 60.

Level checking to correct variations in force retention, temperature changes in output, and individual variations in transmittance of the optical fiber 58, that is, unifying the detection level at each light receiving point that receives reflected light from the scanning line 26. In order to do this, the brightness of the light emitting element 20 is determined for each of these individual light receiving points.

That is, after placing a predetermined reference paper colored at the minimum density to be determined as a line or a point on the surface to be read under the light deflection element 22, the initialization process of step SLI in FIG. 15 is performed by CP and Ulo. is executed, the irradiation data DAC and block data B are cleared to zero, and the content of the deflection data DH is changed to its minimum value DH+++
It is considered in. This minimum value DHffii+s corresponds to, for example, a state in which the irradiation position is located at the left end in FIG. 1 within the irradiation range by the optical deflection element 22. The irradiation data DAC specifies the brightness of the laser beam 50 output from the light emitting element 20. Further, the block data B indicates any of the ranges (blocks) illuminated by the light deflection element 22 on the surface to be read, and indicates the light emitting element 20, light deflection element 22 associated with the block. , and the light receiving element 60. Furthermore, deflection data D.

specifies the deflection angle of the laser beam 50 in the optical deflection element 22, and the deflection control circuit 24 supplies a voltage signal corresponding to the content of the deflection data DH to the optical deflection unit 38.

In the subsequent step SL2, the output signal of the comparator 70 based on the output signal from the light receiving element 60 specified by the block data B, for example, the one located on the leftmost side in FIG. 1, is read, and in step SL3, the output signal is It is determined whether or not it is reversed. If it is determined that it has not been reversed yet, step SL4 is executed, "1" is added to the contents of the irradiation data DAC, and then step SL2 is executed again. Compa Lake 70
This operation is repeated until the output signal of the comparator 7o is inverted. When it is determined that the output signal of the comparator 7o is inverted, step SL5 is executed and the irradiation data DAC at that time is stored in the RAMI4. Note that a value obtained by adding a predetermined margin value to the irradiation data DAC at this time may be stored.

In this way, the initial deflection angular position of the initial block (
(laser beam irradiation position), for example, the left end position of the block, the next step SL
6, the content of block data B is its maximum value B I
It is determined whether IIIM has been reached. Initially, it does not arrive, so step SL7 is executed and "1" is added to the contents of block data B, and then step SL2
The following will be executed: Such an operation is for checking the level of the next adjacent irradiation position within the same block, and is repeated until the contents of block data B reach its maximum value B, □ (=6).

While the above operations are being executed, when it is determined in step SL6 that the contents of block data B have reached its maximum value B□8, the level check of the first deflection position of all blocks is completed, so step SL8 is executed and deflection data D is obtained.

It is determined whether or not has reached its maximum value D)+□8. Initially, it does not reach the target position, so by executing step SL9, "1" is added to the content of the deflection data DH, and the deflection position is changed by one, and then the step S
L2 and below are executed.

While the above operations are repeated, step SL
When it is determined that the deflection data DH has reached its maximum value DH□8 at step 8, the level check routine ends, and the level check at every reflection position along the scanning line 26, that is, at each light receiving position is completed.

When the level check is completed as described above, a signal reading routine for reading images drawn on the paper 62 by lines or dots, such as characters, figures, codes, etc., is performed by the laser beam 50, which is carried out as the paper 62 is fed. Executed on every scan. 5. As shown in FIG. 16, the initialization process of step SSI is executed, the contents of the deflection data DH are set to the minimum value DH@iR, and the contents of the block data B are cleared to zero. In the subsequent step SS2, the irradiation data DAC of each block corresponding to the contents of the deflection data D is set, and the laser beam 50 of the light intensity corresponding to the contents of the irradiation data DAC is output from the light emitting element 20. Initially, the content of the deflection data D is the minimum value, so the irradiation data DAC predetermined in the level check routine is set in order to irradiate, for example, a location located at the left end of each block.

Next, step SS3 is executed and the block data B
The output signal of the comparator 70 corresponding to the block data B is read, and it is determined in step SS4 whether the contents of the block data B have reached its maximum value B-c. Initially, it does not arrive, so the subsequent step SS5 is executed and "1" is added to the contents of the block data B, and then the steps from step SS3 are executed. In this way, a signal based on the reflected light at the initial irradiation position of each block is read.

While the above operations are repeated, the content of block data B reaches its maximum value B in step S85. When it is determined that aX has been reached, it is determined in step S86 whether the content of the deflection data D has reached its maximum deflection data DI1max. Initially, it will not arrive, so
After the subsequent step SS7 is executed and "1" is added to the content of the deflection data DH, the steps from step SS2 onwards are executed. In this way, the irradiation position is changed to the adjacent position and the above-described operation is repeated.

While such operations are repeatedly executed, step SS
When it is determined in step 6 that the content of the deflection data D has reached its maximum value deflection data Do-0, the signal reading routine ends. That is, signals corresponding to lines or points located on the scanning line 26 of the paper 62 are read. The above operation is performed again after the paper 62 is slightly fed in the direction of the arrow in FIG. 14, so that the entire image drawn on the display surface of the cover 62 is optically read.

As described above, according to the present embodiment, the substrate 28 provided with the two-dimensional optical waveguide 32 and the light beam provided on the substrate 28 that deflects the direction of the laser beam 50 passing through the two-dimensional optical waveguide 32 are provided. The direction of the laser beam 50 is deflected by the optical deflection action of the optical deflection element 22, which includes a deflection unit 38 and scans the laser beam 50 on the surface to be read. This eliminates the need for mechanically moving parts such as, making the device smaller, improving reliability and durability, and eliminating noise.

Further, a large number of optical fibers 58 are provided, and the optical fibers 58 are arranged along the scanning line 26 of the laser beam 50 that is scanned onto the surface to be read with the incident side end face facing the surface to be read. Since the reflected light from the surface to be read is guided to the light receiving element 60 by the optical fiber assembly W56 of this type, the optical system becomes simple, and in this respect as well, the apparatus becomes compact and highly reliable.

Although one embodiment of the present invention has been described above, the present invention can also be applied to other embodiments.

For example, in the optical deflection element 22, a three-dimensional optical waveguide is provided in place of the optical deflection section 38, and the three-dimensional optical waveguide is branched into a large number of branches toward the traveling direction of the laser beam. An electrode may be provided to control the branching direction of light using an electro-optic effect, or an optical deflector may be provided that uses an acousto-optic effect, that is, the refractive index within the optical transmission medium is periodically changed by ultrasonic waves. ,
An optical deflection unit may be provided that controls the Bragg diffraction angle (deflection angle) caused by the periodic change in the refractive index by changing the frequency of the ultrasonic wave.

Furthermore, in the above-described embodiments, the detection of reflected light was sequentially performed for each adjacent block in the level check routine or signal reading routine, but the detection may be performed for every other block.

This has the advantage that leakage of irradiation light from adjacent blocks is eliminated and level checking or signal reading becomes more reliable.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a plot diagram showing the configuration of an embodiment of the present invention. FIGS. 2 and 3 are a plan view and a side view of the optical deflection element shown in FIG. 1. Figures 4 to 6 show the second
It is a figure which shows the electric field and refractive index change on the AA line, the BB line, and the CC line of a figure, respectively. 7 and 8 are diagrams showing examples of voltage waveforms supplied to the optical deflection section in the optical deflection element of FIG. 1, respectively. FIG. 9 is a diagram illustrating the luminous flux correcting action of the luminous flux correcting section in the optical deflection element of FIG. 1. FIG. FIG. 10 is a diagram illustrating the electrode arrangement of the luminous flux correcting section in the optical deflection element of FIG. 1. FIG. 11 is a diagram showing changes in the luminous flux when a voltage is applied to the electrodes of the luminous flux correction section in the optical deflection element of FIG. 1. FIG. 12 is a diagram showing an example in which a toroidal lens for beam correction is used on the output side of the optical deflection element. FIG. 13 is a diagram showing in detail the optical deflection element, optical fiber device, and light receiving element shown in FIG. 1. FIG. 14 is a diagram showing how the optical deflection element, optical fiber device, and light receiving element shown in FIG. 1 are installed. 15 and 16 are flowcharts respectively illustrating the operation of the apparatus of FIG. 1. FIG. 17 is a diagram showing a conventional optical reading device. 22: Optical deflection element 28 two substrates (solid optical transmission medium) 32: Two-dimensional optical waveguide (optical waveguide) 56: Optical fiber device 58: Optical fiber 60: Photodetector Applicant Brother Industries, Ltd. Figure 4 + Figure 6 + Figure 7 Section 8 Figure 13

Claims (1)

[Scope of Claims] An optical reading device that reads lines, points, etc. drawn on a surface to be read based on reflected light from the surface to be read obtained when scanning a laser beam, comprising an optical waveguide. a solid-state optical transmission medium provided with a laser beam, and an optical deflection unit provided on the solid-state optical transmission medium to deflect a direction of a laser beam passing through an optical waveguide in the solid-state optical transmission medium, an optical deflection element for scanning a laser beam, a light receiving element for receiving reflected light from the surface to be read, and a large number of optical fibers that guide the reflected light to the light receiving element; An optical reading device comprising: an optical fiber device arranged along a scanning line of a laser beam scanned on the surface to be read with an end face on the entrance side facing the surface to be read.