JP3199932B2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device mounted on a data symbol reader for reading coded information such as two-dimensional data symbols.

[0002]

2. Description of the Related Art Today, for application to, for example, a POS system, a method and apparatus for converting product information into a barcode and reading the barcode with a barcode reader have become widespread.

[0003] However, the barcode is one-dimensionally read by scanning with a laser beam in the bar arrangement direction, and the amount of information is limited.

Therefore, in recent years, a two-dimensional data symbol in which, for example, a black and white mosaic pattern is two-dimensionally arranged has been developed as a device capable of carrying more information. An apparatus for reading this two-dimensional data symbol has been developed. There are almost no devices using an area sensor.

On the other hand, in developing such a data symbol reading device, if a system for simultaneously reading two-dimensional data symbols in a two-dimensional manner is employed, the two-dimensional data symbols arranged in the reading area can be uniformly two-dimensionally read. Since it is necessary to illuminate, it is only necessary to illuminate a straight line uniformly, and if an illuminating device used for reading a one-dimensional code is used, it is not possible to illuminate uniformly, and to illuminate a plane in a reading area simultaneously and uniformly. There is a demand for the development of such devices.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an illumination device capable of uniformly illuminating a symbol reading area.

[0007]

This and other objects are achieved by the present invention described below.

(1) An illuminating device for illuminating a rectangular symbol reading area in a data symbol reading apparatus, comprising: a plurality of light sources for illuminating the symbol reading area; The brightness of the illumination center position when the reference plane is independently irradiated is adjusted for each light source to uniformly illuminate the reference plane, and the brightness of the illumination center position is adjusted from the light source to the illumination center position. A lighting device, which is performed by adjusting a distance to the lighting device.

(2) An illuminating device for illuminating a rectangular symbol reading area in a data symbol reading apparatus, comprising: a plurality of light sources for illuminating the symbol reading area; The brightness of the illumination center position when independently illuminated on the reference plane is adjusted for each light source to uniformly illuminate the reference plane, and the adjustment of the brightness of the illumination center position is performed using the reference plane and the light source. An illumination device, wherein a diffusion optical system is disposed between the optical devices, and the degree of diffusion of the diffusion optical system is adjusted.

(3) The optical axis of the light emitted from each of the light sources is inclined at a predetermined angle with respect to the reference plane of the symbol reading area, and the position of each of the illumination center positions on the reference plane is: From the pair of opposed sides of the reference surface on the light source side, the length of another pair of opposed sides is 0.1 to 0.34.
The lighting device according to the above (1) or (2), which is located within a range of a double distance.

(4) An illuminating device for illuminating a rectangular symbol reading area in a data symbol reading apparatus, comprising: a plurality of light sources for illuminating the symbol reading area; The brightness of the illumination center position when illuminated on the reference plane alone is adjusted for each light source to uniformly illuminate the reference plane, and the optical axis of the light emitted from each light source is determined by the symbol reading area. Is inclined at a predetermined angle with respect to the reference plane, and the position of each of the illumination center positions on the reference plane is from a pair of opposite sides of the reference plane on the light source side to another pair of opposite sides. A lighting device characterized by being located within a distance of 0.1 to 0.34 times the length.

(5) The brightness at each illumination center position of the plurality of light sources is adjusted so that the one located at the outer end thereof in the arrangement state is the highest. The lighting device according to any one of the above.

(6) The lighting device according to any one of (1) to (5), wherein the data symbol reading device is a device that reads a data symbol in which codes are two-dimensionally arranged.

(7) A first light source array in which a plurality of light sources are arranged and a second light source array in which a plurality of light sources are arranged are provided on each side of a pair of opposite sides of the symbol reading area. The lighting device according to any one of the above (1) to (6).

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lighting device according to the present invention.

FIG. 1 is a sectional side view schematically showing a configuration example of a data symbol reading device. As shown in FIG. 1, the data symbol reading device 1 has a casing 2, in which an illuminating device 40 and a reading unit 4 that reads a data symbol 38 are installed in an integrated state. Have been.

The lighting device 40 is connected to a light source driving circuit 42 for lighting a light source 41 constituting the lighting device 40. As the light source 41, for example, a light emitting element such as an LED, a halogen lamp, a semiconductor laser, or the like can be used.

Between the light sources 41, a CCD (charge coupled device) 43, which is an area sensor, and this CCD 43
A reading unit 4 including an optical system 44 for guiding reflected light in a symbol reading area 2 to be described later so as to form an image at 43 is provided. In the CCD 43, a large number of pixels are arranged in a matrix, and each pixel accumulates charges corresponding to the amount of light received by each pixel, and discharges the charges sequentially at a predetermined time. The discharged charges constitute an image signal of the read image.

In this embodiment, the CCD 43
May be any as long as it can detect the brightness (luminance) of each part of the data symbol 38. Depending on the configuration of the data symbol to be read, a CCD 43 for a color image may be used. Further, the optical system 44 is configured by combining optical components such as various lenses, prisms, filters, and mirrors as desired.

FIG. 2 is a plan view showing the symbol reading area 36. As shown in the figure, a symbol reading area (indicated by a dashed line in the figure) 36 is provided on a reference plane (a plane on which the data symbol 38 is located) 37 on an illumination device 40.
Is an area where the light is irradiated and the reflected light is received by the reading unit 4 so that the data can be read.

In the illustrated configuration, the data symbol (symbol code) 38 is composed of a black or white (or transparent) mosaic arranged in x rows × y columns (x and y are integers of 2 or more). . The black or white of this mosaic represents, for example, 0 or 1 in a binary system, and desired information is specified by this combination. It should be noted that the data symbol 38 is not limited to the one shown in the figure.

In the illuminating device 40 and the reading unit 4, the light sources 41 arranged as described later are turned on by the light source driving circuit 42, and the light emitted from each light source 41 irradiates the symbol reading area 36. The reflected light is imaged on the light receiving surface of the CCD 43 via the optical system,
An image signal (analog signal) corresponding to the amount of received light is output.

Hereinafter, a first embodiment of the illumination device 40 will be described in detail with reference to FIG. The illuminating device 40 includes an array 45, 46 of a plurality of light sources 41, and a diffusion plate 4 provided between the light sources 41 and the symbol reading area 36.
7 and 48.

In this embodiment, the arrays 45 and 46 are respectively constituted by three light sources 41a, 41b and 41a. The arrays 45 and 46 are arranged above the symbol reading area 36 along both long sides of the symbol reading area 36 in the reading state. Further, in this embodiment, the diffusion optical system includes diffusion plates 47 and 48 having a diffusion surface.
However, another optical system such as a cylindrical lens may be used.
Further, when a light source having low directivity is used, the diffusion optical system may not be used. Light sources 41a and 41b of the present embodiment
Are shown in FIG.

The light source 41 constituting each of the arrays 45 and 46
a, 41b, and 41a, each optical axis 49a, 49b, 49a
Are parallel to each other, and these optical axes 49a, 4a
The plane including 9b and 49a is the symbol reading area 36.
Intersect with the reference plane 37 at a predetermined angle.
The line of intersection between the plane and the reference plane 37 is parallel to both long sides of the symbol reading area 36, and the plane is provided so as to open outward toward the CCD 43.

The angle formed between the plane including the optical axes 49a, 49b and 49a and the reference plane 37 is 30 to 60 °,
Preferably it is 40 to 50 °. Such an angle range is preferable because illumination with respect to the reference plane 37 by the illumination device of the present invention is more uniform.

Further, the straight line n of a position where the plane and the reference plane 37 intersects is parallel to the center line m _y bisecting the parallel and short side to long sides of the symbol reading area 36, and the With respect to the straight line n, each optical axis 49a in the plane,
49b and 49a each intersect at right angles. This intersection is the illumination center position P _a by the light source, P _b, next to P _a,
The illumination center positions P _a , P _b , and P _a become the centers of the illumination portions of the respective light sources. Lighting center position P _a, P _b, P _a is
In the light source having the light distribution characteristics as in the present embodiment, the light source becomes the brightest part when the reference surface 37 is irradiated with a single light source.

The light emitted from the light source 41 is
7 and 48, the light distribution area of the light is expanded, and the light is spread and irradiated within a certain range in the symbol reading area 36.

Here, the brightness of the light sources 41a, 41b and 41a constituting the respective arrays 45 and 46 is
The light sources 41a and 41a located at both ends of the light sources 5 and 46 are the same, and the light source 41b located at the center has lower brightness (darker) than the other light sources 41a.

The light source 41a, 41b, the 41a upon irradiation with the sole, the luminance of the reference plane 37 in the illumination center position P, as compared to P _b, P _a becomes brighter. In such a configuration, when all the light sources 41 are turned on,
Adjacent light sources 41a, diffused light from 41a is, and from both sides to the vicinity of the illumination center position P _b of the light source 41b, each part of the straight line n is uniformly illuminated. Then, for example, as the center line m _y, even on a straight line of any parallel to the straight line n, in respective linear direction it is uniformly irradiated respectively, each part of the luminance becomes comparable.

The light sources 41 constituting the arrays 45 and 46 have four light sources.
If there is more than one, the symbol reading area 36 can be uniformly illuminated in the same manner as described above by arranging the elements at the outer end of the array so that the luminance is high. When the arrangement intervals of the light sources that constitute the array are substantially equal, it is preferable that the light sources with high luminance have the same luminance, and the light sources with low luminance also have the same luminance. The arrangement of such illumination center position P is relative to the center line m _y, is preferably symmetrical.

Further, the difference in brightness can be provided by previously disposing a light source having different brightness or by changing the driving voltage of the light source. Specifically, the configuration may be such that the applied voltage of the light source for increasing the luminance is increased and the applied voltage of the light source for decreasing the luminance is decreased. In the first embodiment,
The driving voltage of the light source 41b is set lower than that of the light source 41a. Therefore, the light distribution characteristics do not change, but the light intensity is reduced.

The position of the straight line n in the short side direction is
As shown in FIG. 3, it is located at a distance ΔL from the long side. This range of ΔL is preferably within a range of 0.1 to 0.34 times the short side, more preferably 0.15 to 0.25 times the short side. As a result, the reference surface 37 of the symbol reading area 36 is two-dimensionally and evenly illuminated, and the difference in luminance between the components is further reduced.

Next, another embodiment of the above-described first embodiment will be described. In a second embodiment, for example, as shown in FIG.
Of the central light source 41b and the symbol reading area 36
Is longer than the distance of the other light source 41a. With such a configuration, the illumination portion near the illumination center position P _b, the luminance by the illumination of the light source 41b, can be made smaller than other portions.

As shown in FIG. 6, in the third embodiment, the diffusion plates 47 and 48 are separately divided for each light source 41, and the diffusion plates 47a, 47b, 47
a, 48a, 48b, and 48a are provided, respectively, and the diffusing plates 47b and 48b disposed in the central light source 41b have different diffusivities and transmittances. In this configuration, the diffusion plate 47b, or to increase the diffusion of the 48b, or by the transmissivity is lowered, lighting portion near the illumination center position P _b, the luminance by the illumination of the light source 41b, than other portions I'm making it smaller.

[0036] As the fourth embodiment, the optical path of the light source 41b, by installing the optical filter is a light reduction means are configured to dim the light reaching the illumination center position P _b.

In the case of the second, third and fourth embodiments, all light sources having the same characteristics can be used, and components can be unified.

[0038] In the illumination device described above, the lighting portion is a symmetrical with respect to the center line m _x perpendicular to the center line m _y symbol reading area 36. Thus, the symbol reading area 36 can be more uniformly illuminated by locating the respective illumination portions.

A signal processing circuit 5 for processing an image signal from the reading section 4 is provided in the casing 2.
As shown in FIG. 7, this signal processing circuit 5
CD drive circuit 6, amplifier circuit 8, binarization circuit 10, memory 12, control means (CPU) 15, communication driver 1
6 and these connection lines.

The control means 15 includes a light source driving circuit 4
2 and, if necessary, a switch circuit and an LCD (liquid c
A display unit (not shown) such as a crystal display is connected.

The signal processed by the signal processing circuit 5 is decoded into necessary data, and then is decoded.
Is input to an external computer 17 such as a personal computer or a workstation. In such a computer 17, the input data is stored and counted.

The light source drive circuit 42 is a circuit for supplying electric power to the light source 41 and lighting it, and is controlled by the control means 15. When the main switch is turned on, the control means 15 activates the light source drive circuit 42, thereby turning on the light source 41. Here, the lighting time of the light source 41 is set as desired by the light source driving circuit 42 or the control unit 15.

When the main switch is turned on, the control means 15 activates the CCD drive circuit 6. CCD
The drive circuit 6 outputs a CCD horizontal drive pulse and a CCD vertical drive pulse to the CCD 43 to control the accumulation and transfer of charges in the CCD 43.

The CCD drive circuit 6 generates a clock signal, and sends a signal (composite clock signal) obtained by combining this signal with a horizontal synchronizing signal and a vertical synchronizing signal to the control means 15.

An image signal (analog signal) sequentially output from the CCD 43 of the reading unit 4 is amplified by the amplifier circuit 8, A / D converted, and input to the binarization circuit 10.

In the binarizing circuit 10, the digital image signal is binarized by comparing it with threshold data. The binarized data output from the binarization circuit 10 is input to a predetermined address of the memory 12 by an address counter built in the control unit 15. The address counter is driven by a composite clock signal input from the CCD driving circuit 6.

Data is sequentially read from the memory 12 in accordance with the address designated by the built-in address counter. The data of one screen is subjected to, for example, contour detection ( It performs image processing such as extraction of only information relating to the data symbol 38), dropout correction, rotation, and the like.
The data is decoded into data according to the data symbol system by a decoder built in the. The decoded data is output to the host computer 17 via the communication driver 16.

The number of light sources and the illumination center position P are appropriately changed according to the size of the symbol reading area, the light distribution characteristics of the light sources, the luminance, and the like.

Further, the embodiment of the present invention is not limited to the above-described embodiment, and the symbol reading area may have a different size, or the area may have a square shape.

Next, the present invention will be described in more detail with reference to specific examples. The luminance distribution of the symbol reading area was measured using the illumination device having the structure of the first embodiment shown in FIG. All the six light emitting diodes used as the light source had the same characteristics, and the light distribution characteristics were as shown in FIG. The size of the symbol reading area is L _x (short side) = 18.5 mm, L _y
(Long side) = 24.5 mm. Other conditions were measured under the following conditions.

FIG. 8 shows the luminance distribution of the symbol reading area 36 when the symbol reading area 36 shown in FIG. 2 is irradiated under the following conditions. The vertical axis represents the level of the video signal on the straight line n (unit: IRE), and the horizontal axis indicates the position on the straight line n. Position of the illumination center position P is a distance from the short side of the symbol reading area 36 to the illumination center position P _a and L _1, and the distance between the illumination center position P _a and the illumination center position P _b and L _2, L ₁ : L ₂ =
The position was set at a ratio of 5: 7.

[0052] The illumination center position P _a, the distance from P _b, the long sides of P _a is set to 0.2 times at a distance of the short side, the optical axis from the light source 41, the reference plane 37 The angle with respect to the normal was 45 °.

The curve shows the luminance distribution on the straight line n, and the flatter it is, the more uniformly the straight line n is illuminated.

<Comparative Example>

The brightness of the light source 41b is changed to the other light sources 41a,
And 1a the same as the luminance of the illumination center position P _b by a single light source 41b, and a brightness of the illumination center position P _a by single light source 41a, as the same were subjected to the above measurement . The results are shown in FIG.

<Example 1>

The light source drive circuit is provided with a resistor, and the light source 41 is provided.
b, the driving voltage of the other light sources 41a,
Darker than 1a, the brightness of the illumination center position P _b by a single light source 41b is, in a state where reduced by about 17% than the brightness of the illumination center position P _a by single light source 41a, was subjected to the above measurement . The result is shown in FIG.

<Results>

As shown in FIG. 8A, in the comparative example, the luminance near the center is high, and the relative difference e ₁ between the bright and dark parts is equal to the difference e ₂ (FIG. 8
(B)). That is, it can be seen that the embodiment of the present invention is more uniformly illuminated on the straight line n in the symbol reading area 36 than the comparative example. Were also measured for the luminance distribution on the center line m _x perpendicular to the straight line n (short side direction), there is a difference e ₂ or less of a difference in brightness in the long side direction.

<Embodiment 2>

In addition to the configuration used in the first embodiment, the same light source as that in the first embodiment has the same brightness at the same angle and the same illumination center position, and the light source 41b is replaced by another light source 4b.
By avoiding far from the reference plane 37 than 1a, the luminance of the illumination center position P _b, as the same luminance as in Example 1, was subjected to the above measurement, almost the same results as in Example 1 Obtained.

<Embodiment 3>

The structure is such that a diffusion plate is provided for each light source.
Diffuser 47b 1b, the by larger than the other of the diffusion plate diffusion of the 48b, where the luminance of the illumination center position P _b, as the same luminance as in Example 1, was subjected to the above measurement, Example Approximately the same result as the result of No. 1 was obtained.

<Embodiment 4>

[0065] Between the light source 41b and the reference surface 37, by arranging a filter, by dimming the light emitted from the light source 41b, the luminance of the illumination center position P _b, the same luminance as in the above embodiment As a result, the same result as that of Example 1 was obtained.

[0066]

As described above, according to the lighting apparatus of the present invention, a two-dimensional symbol reading area can be uniformly illuminated, and coded information can be read accurately.

The optical axis from the light source is inclined with respect to the reference plane of the symbol reading area, and the illumination center position is provided in a predetermined range from the edge of the reference plane, so that the symbol reading area can be more uniformly illuminated. can do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view schematically illustrating a configuration example of a data symbol reading device.

FIG. 2 is a plan view showing a symbol reading area.

FIG. 3 is an overall perspective view illustrating a configuration of a lighting device and a reading unit.

FIG. 4 is a graph showing light distribution characteristics of a light source (light emitting diode).

FIG. 5 is an overall perspective view illustrating a configuration of an illumination device and a reading unit according to a second embodiment.

FIG. 6 is an overall perspective view illustrating a configuration of a lighting device and a reading unit according to a third embodiment.

FIG. 7 is a circuit diagram showing a circuit configuration of a data symbol reading device.

8A and 8B show a luminance distribution in a symbol reading area, where FIG. 8A is a luminance distribution in a comparative example, and FIG. 8B is a luminance distribution in an example.

[Explanation of symbols]

Reference Signs List 1 data symbol reading device 2 casing 4 reading unit 40 lighting device 41a light source 41b light source 42 light source driving circuit 43 CCD 44 optical system 45 array 46 array 47 diffusion plate 48 diffusion plate 49 optical axis 5 signal processing circuit 6 CCD driving circuit 8 amplification circuit 10 binarization circuit (comparator) 12 memory 15 controller (CPU) 16 for communication driver 17 host computer 36 symbol reading area 37 reference plane 38 data symbols m _x, m _y centerline P illumination center position

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06K 7/10 G06T 1/00

Claims (7)

(57) [Claims] 1. A data symbol reading device, comprising:
An illumination device for illuminating a rectangular symbol reading area, comprising: a plurality of light sources for illuminating the symbol reading area; and an illumination center when light from the light source is independently applied to a reference surface of the symbol reading area. The brightness of the position is adjusted for each light source to uniformly illuminate the reference plane, and the adjustment of the brightness of the illumination center position is performed by adjusting the distance from the light source to the illumination center position. Lighting device characterized by the following. 2. A data symbol reading device, comprising:
An illumination device for illuminating a rectangular symbol reading area, comprising: a plurality of light sources for illuminating the symbol reading area; and an illumination center when light from the light source is independently applied to a reference surface of the symbol reading area. The brightness of the position is adjusted for each light source to uniformly illuminate the reference plane. The adjustment of the brightness of the illumination center position is performed by disposing a diffusion optical system between the reference plane and the light source, An illumination device, which is performed by adjusting the degree of diffusion of an optical system. 3. An optical axis of light emitted from each of the light sources,
The symbol reading area is inclined at a predetermined angle with respect to a reference plane, and the position of each of the illumination center positions on the reference plane is defined by a pair of opposite sides of the reference plane on the light source side. The lighting device according to claim 1, wherein the lighting device is located within a distance of 0.1 to 0.34 times a length of the opposite side. 4. A data symbol reading device,
An illumination device for illuminating a rectangular symbol reading area, comprising: a plurality of light sources for illuminating the symbol reading area; and an illumination center when light from the light source is independently applied to a reference surface of the symbol reading area. The brightness of the position is adjusted for each light source to uniformly illuminate the reference plane, and the optical axis of light emitted from each light source is inclined at a predetermined angle with respect to the reference plane of the symbol reading area. The position of each illumination center position on the reference plane is 0.1 to 0.34 times the length of the other pair of opposite sides from the pair of opposite sides of the reference plane on the light source side. A lighting device characterized by being located within a range of a distance. 5. The brightness of each of the plurality of light sources at an illumination center position is adjusted so that the brightness at the outer end thereof is highest in the arrangement state. Lighting equipment. 6. The lighting device according to claim 1, wherein the data symbol reading device is a device that reads a data symbol in which codes are two-dimensionally arranged. 7. A first light source array in which a plurality of light sources are arranged, and a second light source array in which a plurality of light sources are arranged are provided on respective sides of a pair of opposite sides of the symbol reading area. The lighting device according to claim 1.