JP3067415B2 - Optical reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an optical reader. 2. Description of the Related Art Bar code readers used in POS systems and the like use a semiconductor laser as a light source, or use a hologram in a reading window, and the miniaturization of the apparatus is promoted without lowering the reading performance. However, in order to further reduce the size, it is necessary to reduce the size of a polygon mirror (polygon mirror) that generates scanning light and receives signal light.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view of a conventional optical system, and FIG. FIG. 6 shows an example of an optical system of a stationary bar code reading device in a POS terminal device. This device is provided with a hologram (hollow window 9) provided in a reading window and provided opposite to the hollow window 9. Bottom mirror 11, three three-way split mirrors 1
2, concave mirror 1 provided as a pair with three-way split mirror 12
4 (partially omitted), a polygon mirror 10, a motor 13 for rotating the polygon mirror 10, a light source 1 for emitting laser light, and the like.

FIG. 7A shows an optical path of the scanning light 50 having the configuration shown in FIG. Light emitted from the light source 1 is reflected by a mirror 15 disposed behind a central concave mirror 14 and enters a polygon mirror 10. The incident light reflected by the polygon mirror 10 rotated by the motor 13 repeatedly scans the three sets of three-sided split mirrors 12, where the light is split into three-directional scanning lights 50 and then reflected by the bottom mirror 11. , And enters the hollow window 9. Holograms corresponding to the scanning light 50 are formed in the hollow window 9 and diffract light in different directions. The hollow window 9 generates scanning light 50 in three directions, and scans the barcode label 8 on the product.

FIG. 7B shows an optical path of reflected light (hereinafter, signal light 51) from the bar code label 8 scanned by the scanning light 50 of FIG. 7A. Barcode label 8
The signal light 51 scattered by is collected by the hollow window 9, enters the concave mirror 14 via the bottom mirror 11, the three-way split mirror 12, and the polygon mirror 10, is further converged and reflected by the concave mirror 14, and is reflected by the mirror 17 via the detector 17. Guided to 16. The signal light 51 is converted into an electric signal by the detector 16 and converted into a numerical code by a demodulation unit (not shown).

[0005]

In the conventional optical reader described above, miniaturization and thinning of the optical system have been promoted by various methods. For example, instead of guiding the light (signal light 51) received by the polygon mirror 10 to the concave mirror 14, the surface of the polygon mirror 10 is formed so as to be guided to the bottom mirror 11, and the bottom mirror 11 to which the signal light 51 impinges. A reflection hologram is formed in the area of
Light is collected above 11 and detected. This allows concave mirrors
Since 14 is not required, a reduction in thickness can be achieved. Here, if the size of the polygon mirror 10 can be reduced, further reduction in the thickness and size of the optical system can be expected.

The size, especially the height (h in FIG. 7 (a)) of the polygon mirror 10 is determined based on a demand for securing a light amount necessary for detecting a bar code signal from the scattered signal light 51. At present, it is about h = 20 m / m. However, when the scanning light 50 is generated, the light reflected by the mirror 15 only enters the narrow region along the line L perpendicular to the rotation axis of the polygon mirror 10, as shown in FIG. Therefore, if the polygon mirror 10 is not provided with a function of receiving the signal light 51, the thickness of the polygon mirror 10 can be significantly reduced.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an optical reader in which a polygon mirror does not receive signal light and the polygon mirror has a reduced thickness.

[0008]

FIG. 1 is a principle view of the present invention. Reference numeral 2 denotes a polygon mirror which generates scanning light 50 by reflecting light while rotating. Reference numeral 3 denotes an optical path separating unit that guides the signal light 51 reflected from the reading target 40 based on the scanning light 50 to an optical path in a direction different from the optical path to the polygon mirror 2.

[0009]

The signal light 51 reflected from the object to be read 40 corresponding to the scanning light 50 is scattered in the vicinity of the scanning light path.
(The signal light in the area to be received by the conventional polygon mirror)
The light path separating means 3 guides the light to a light path different from the light path to the polygon mirror 2. Thereby, the polygon mirror 2
It is not necessary to receive the signal light 51, so its size, mainly its thickness (height), may be determined in consideration of only the generation of the scanning light 50. As a result, the light from the light source 1 is a sufficiently converged beam.
The polygon mirror 2 having only the function of generating the above can be made much thinner than the conventional example.

In the case of an apparatus which scans the scanning light 50 from the polygon mirror 2 in three directions using a reflection mirror, for example, a three-way split mirror, a three-way split mirror can be used as the optical path separating means 3. That is, the central strip-shaped portion (reflection surface 4a of the scanning light 51 in FIG. 1) in the three-sided split mirror where the scanning light 50 is scanned by the polygon mirror 2 emits the scanning light 51 in a predetermined direction as in the related art. The other surface (reflecting surface 4b of the signal light 51) has a predetermined angle θ with respect to the reflecting surface 4a of the scanning light 51 so as to be directed to the polygon mirror 2 in the direction of the polygon mirror 2. The signal light 51 is guided in a direction different from that of the signal light 51.

When detecting the separated signal light 51, the signal light 51 having an area determined by the size of the reflection surface 4b and the like is used.
Moves in parallel with the scanning direction on the three-sided split mirror as the optical path separating means 3 along with the scanning of the scanning light 50, so that the detector (6 in FIG. 1) has a moving length such as a CCD (6). A one-dimensional image sensor such as a Charge Coupled Device) or a two-dimensional image sensor is used. Then, the detector is placed in parallel with the moving direction and its light receiving surface is set at right angles to the direction of the signal light 51.

Here, since the CCD is a storage type, there is a possibility that charges due to other light (noise) may be stored in a portion other than the light receiving surface of the signal light 51 corresponding to the scanning light 50, and the noise light is incident. In order to prevent this, an optical mask (5 in FIG. 1) having a light transmission window (hereinafter, referred to as a window) that moves together with the scanning light 50 and transmits only the corresponding signal light 51 is provided on the light receiving surface of the detector. With this optical mask, a function similar to the recombination function of the conventional polygon mirror (a function of reflecting light other than signal light on the scanning optical path in a direction other than the detector) can be provided.

As described above, the signal light is reflected by the polygon mirror 2.
Since the light receiving device 51 is configured not to receive light, the thickness of the polygon mirror 2 can be greatly reduced, and the thickness and size of the optical reader can be reduced, including downsizing of a motor for rotating the polygon mirror 2. be able to.

[0014]

FIG. 1 is a principle view of the present invention, FIG. 2 is a configuration diagram of one embodiment, FIG. 3 is a sectional view of an optical system of one embodiment, FIG. FIG. 5 is a diagram showing an image on the detector. Note that the same reference numerals represent the same object throughout the drawings.

In this embodiment, a bar code reader is taken as an example, and an example is shown in which the three-way split mirror 12 shown in the conventional example (FIG. 6) is used as the optical path separating means 3. In this case, as shown in FIG. 2, three sets of three-way splitting mirrors 4A, 4B,
The signal lights 51 separated at 4C are detected by the corresponding detectors 6A, 6B, 6C. These three sets of three-way splitting mirrors 4A, 4B, 4C for optical path separation and the corresponding detectors 6A, 6B,
6C have the same configuration and perform the same operation as a pair, and therefore, one pair will be described below.

FIG. 3 is a sectional view of a portion of a three-way splitting mirror 4B for separating an optical path. As shown in FIG. 1, the mirror surface of the three-way splitting mirror 4B for optical path separation has a central band-shaped surface (reflection surface 4a) scanned by the scanning light 50, and both sides of the reflection surface 4a and the reflection surface 4a. And the reflection surface 4b of the signal light 51 having an angle θ therebetween. Then, the reflecting surface 4a and the polygon mirror 2 are opposed to each other so that the scanning light 50 is emitted to the outside of the device through a predetermined optical path. Thereby, the signal light 51 that has been reflected near the same optical path as the scanning light 50 is reflected by the reflecting surface 4b.
The light is reflected in a direction D different from that of the polygon mirror 2, and is detected by a detector 6B provided on the optical path.

When the signal light 51 whose optical path has been separated is detected at an intermediate position between the polygon mirror 2 and the three-way splitting mirror 4B for optical path separation, the signal light is separated along with the movement of the scanning light 50 on the detection surface. Move in parallel to the scanning direction (X direction) on the three-way split mirror 4B. (However, if the other optical system is the same as that of the conventional example shown in FIG. 6, the signal light 51 is directed toward the polygon mirror 2 in the X direction. Approximately 15
Therefore, a CCD (CCD 6B) having a length corresponding to the moving amount is used as the detector 6B. That is, between both ends of the three-way splitting mirror 4B for optical path separation (P1
~ P2), the CCD 6B having a length on which the signal light 51 corresponding to the scanning light 50 for scanning
It is placed parallel to the above scanning direction and perpendicular to the direction of the signal light 51. A period during which P1 and P2 are scanned is defined as a charge accumulation time in the CCD 6B. For this reason, noise light may be incident on the other surface of the CCD 6B except the surface on which the signal light 51 is incident, and may accumulate by being superimposed on the charge of the signal light 51. Accordingly, an optical mask 5B having a window W for transmitting only the signal light 51 is placed on the light receiving surface of the CCD 6B.

FIG. 4 shows a detector using liquid crystal as an optical mask and three CCD line image sensors in parallel as detectors 6A, 6B and 6C (each detector in FIG. 2, each light detector). 2 shows a configuration example of a mask, window control units 28A to 28C, and a reading unit 30). The reason why three line sensors are used is that when the light amount of the signal light 51 is insufficient, it can be dealt with by using the line sensors in parallel. Of course, a two-dimensional sensor may be used. When a two-dimensional sensor is used, as shown in FIG. 5, an image of the reading target 40 is accumulated on the two-dimensional sensor, and a barcode is read from the two-dimensional image by image processing or the like. Alternatively, an image of one to a plurality of lines is extracted from the two-dimensional image and the barcode is analyzed. This case corresponds to using one or more line sensors.

Here, in order to control each CCD and optical mask in synchronization with the scanning light 50, each of the CCDs and optical masks is moved to a position as shown in FIG. Scanning light 50 for each of three-sided split mirrors 4A, 4B, 4C
Are provided, respectively.
Then, triggered by the detection of the scanning light 50 by the optical sensors 41A, 41B, and 41C, the charge accumulation control and readout control of the CCDs 6A, 6B, and 6C, and the window control of the optical masks 5A, 5B, and 5C, respectively. Do.

In FIG. 2, it is assumed that the polygon mirror 2 rotates counterclockwise. Now, when the scanning light 50 is detected by the optical sensor 41B, the CCD timing signal generation circuit 30
Represents a storage time T0 for generating a shift signal having a time interval T0 by a timer (not shown), receiving the signal light 51, and storing the charge thereof (the scanning light 50 is used to scan the three-way split mirror 4B for optical path separation). (Corresponding to the scanning time) is set to CCD 6B. Here, when the shift signal is at the low level, the charge corresponding to the incident light is stored in the storage unit of the CCD 6B, and when the shift signal is at the high level, the stored charge is transferred to the charge transfer unit of the CCD 6B. And Then, the charges accumulated in the charge transfer unit are sequentially read for each pixel by the read signal.

On the other hand, the window control unit 28B turns on all the Y-direction terminals of the optical mask 5B as a liquid crystal,
When the scanning light 50 is detected at 41B, the X-direction terminals are sequentially selected from X0 to Xn based on the timer 29B, and an ON signal having a width T1 is applied. The time T1 and the selection time t0 are determined by the resolution of the liquid crystal, the width of the window W, the scanning time of the three-way split mirror 4B for separating the optical path of the scanning light 50, and the like.

As described above, the window (transmission window) W for passing only the effective signal light 51 moves in response to the scanning light 50, and the charges of only the effective signal light 51 are accumulated in the CCD 6B. Will be.

The above operation is performed by the three-way split mirror 4 for separating the optical path.
The same applies to A and 4C, and the above control is performed at a speed (1 to 2 mS) according to the rotation speed (about 4000 rpm) of the polygon mirror 2 and the number of faces (the number of sides of the polygon, for example, 5).

If the CCD 6B is composed of three line sensors, the signal light 51 transmitted through the window W is:
The charge is accumulated in each line sensor and read out synchronously. Each pixel signal is added and amplified by the addition amplifier 21B, binarized by the binarization circuit 22B, and input to the bar width conversion unit 24 through the switching circuit 23.
Here, after the conversion to the bar width of the white / black bar, the barcode recognition unit 25 verifies whether or not the barcode is present. If it is recognized as a barcode, it is stored in the memory 26 and then demodulated.
Converted to numerical code by 27. The switching circuit 23
Are switched by the CCD timing signal generation circuit 30 according to the detection signals of the optical sensors 41A, 41B, 41C in accordance with the readout periods of the CCDs 6A, 6B, 6C. For example, when the optical sensor 41B is turned on, immediately after the end of the accumulation time T0 of the CCD 6A, the switching circuit 23 is switched to the CCD 6A side and the read signal is input to the bar width conversion unit 24. Thus, each time a product is scanned, a plurality of barcode signals read by each of the CCDs 6A, 6B, 6C are stored in the memory 26,
The demodulation unit 27 determines whether the reading is OK or not by performing the matching verification of each bar code signal and the like.

As described above, with the rotation of the polygon mirror 2, the scanning light 50 scans the three-way split mirror 4, and as a result, the signal light 51 reflected from the bar code label 8 is transmitted by the three-way split mirror 4 to the polygon mirror 2 The bar code can be read by being guided in a direction different from the above, and being detected by the detector 6 directly. At this time, since the window control of the optical mask 5 is performed in synchronization with the scanning light 50, the signal light 51 recombined with the detector 6 can be received.

As described above, according to the present invention, since the optical system is configured so that the signal light 51 is received without passing through the polygon mirror 2, the polygon mirror 2 is dedicated to scanning. Light source 1
Since the light beam from the polygon mirror 2 is sufficiently narrow, the thickness h ′ (FIG. 3) of the polygon mirror 2 can be greatly reduced. Also,
As a result, the size of the motor 7 for rotating the polygon mirror 2 can be reduced.

In this embodiment, an example in which the three-sided split mirror 4 is used as the optical path separating means 3 has been described. However, depending on the configuration of the optical system, the optical path may be separated by a reflecting mirror other than the three-sided split mirror 4, a half mirror, or the like. Means may be formed, and it goes without saying that the present invention is applied without departing from the spirit of the present invention.

[0028]

As described above, the optical reading apparatus according to the present invention has an optical system configured to detect reflected light (signal light) without passing through a polygon mirror. Therefore, since the polygon mirror does not require an area for receiving light, the thickness of the polygon mirror can be greatly reduced and the rotation motor of the polygon mirror can be downsized. Therefore, the effect of contributing to miniaturization of the optical reader is great.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment.

FIG. 3 is a sectional view of an optical system according to an embodiment;

FIG. 4 is a configuration diagram of a detection unit according to an embodiment.

FIG. 5 is a diagram showing an image on a detector.

FIG. 6 is a perspective view of a conventional optical system.

FIG. 7 is a diagram showing scanning and focusing in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Light source 2 Polygon mirror 3 Optical path separation means 4A, 4B, 4C Three-plane split mirror 4a Reflection surface of scanning light 4b Reflection surface of signal light 5, 5A, 5B, 5C Optical mask 6 Detector 6A, 6B, 6C CCD 7 Motor 8 Bar code label 9 Hollow window 10 Polygon mirror 11 Bottom mirror 12 Three-way split mirror 13 Motor 14 Concave mirror 15 Mirror 16 Detector 17 Mirror 21A, 21B, 21C Additive amplifier 22A, 22B, 22C Binarization circuit 23 Switching circuit 24 Bar width Conversion unit 25 Barcode recognition unit 26 Memory 27 Demodulation unit 28A, 28B, 28C Window control unit 29B Timer 30 CCD timing signal generation circuit 31 Reading unit 40 Reading target 41A, 41B, 41C Optical sensor 50 Scanning light 51 Signal light

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-229384 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06K 7/10 G06T 1/00

Claims (4)

(57) [Claims] 1. An optical reading device comprising a polygon mirror (2) for scanning light and reading a signal light (51) reflected from an object to be read (40) based on the scanning light. An optical path separating means (3) for separating the optical path of (50) from the optical path of the signal light (51) is provided on the scanning optical path, and the optical path separating means (3) defines an optical path to the polygon mirror (2). An optical reading device for guiding the signal light to different optical paths and reading the signal light. 2. The optical path separating means is constituted by a reflection mirror, and has a predetermined angle between a reflection surface of the scanning light and a reflection surface of the signal light in the reflection mirror. The optical reader according to claim 1, wherein: 3. The optical reader according to claim 1, wherein the detector for detecting the signal light is a one-dimensional image sensor or a two-dimensional image sensor. 4. The optical reader according to claim 3, wherein an optical mask for blocking light other than the signal light is provided on a light receiving surface of the detector.