JP2005258817A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of fetching a carried object as an image with little blur while realizing cost reduction. <P>SOLUTION: The image reader 1 has a case body 3 and, on an upper plate 3a of the case body 3 a transparent plate 4 is fixed. The inside of the case body 3 has a plurality of light sources 11 for irradiating lights outward and a reflecting plate 12 for reflecting irradiated lights from the respective light sources 11 towards a read part 4a on the transparent plate 4. A CMOS image sensor 14 for photographing a coin 2 which has reached the read part 4a is arranged at a lower position of the light sources 11 inside the case body 3. Between the transparent plate 4 and the CMOS image sensor 14, a phosphorescent glass 15 for emitting phosphorescence P when irradiated by the light sources 11 is arranged. Also, the image reader 1 has an arrival detection sensor 17 for detecting whether or not the coin 2 has been carried to the read part 4a and a light source control unit for executing a control so that the respective light sources 11 are lighted just for a specified period of time when the coin 2 has been carried to the read part 4a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that reads an image of coins, medals, and the like passing on a conveyance path.

As an image reading apparatus that reads an image of a coin or the like passing on a conveyance path, for example, an apparatus described in Patent Document 1 is known. The image reading apparatus described in this document is disposed inside the housing, and is disposed at an illumination unit that illuminates the upper surface (reading surface) of the housing and a position below the reading surface inside the housing. And a CCD camera for imaging the reading object conveyed to the upper surface.
JP-A-9-282513

  In the above prior art, it is possible to capture a reading object conveyed at high speed and randomly as a still image without blurring. However, in recent years, it has been promoted to construct such an image reading apparatus at a lower cost.

  An object of the present invention is to provide an image reading apparatus capable of capturing an object to be conveyed as an image having almost no blur while reducing costs.

  According to the present invention, in an image reading apparatus that reads an image of an object passing on a conveyance path, a light source that irradiates light to a reading part of the conveyance path and a light source that is turned on for a predetermined time when the object is conveyed to the reading part. When the light source control means for controlling the object, the image pickup device for picking up an image of the object when the object is transported to the reading part, and the reading part and the image pickup element are disposed, And a phosphorescence generating member that emits phosphorescence, and the imaging element captures an afterimage of an object generated by phosphorescence.

  Here, the image sensor is preferably a CMOS image sensor. A CMOS image sensor is less expensive than a CCD image sensor, but is a line-sequential readout type imaging means. Therefore, even if an object that is transported at high speed on the transport path is captured as it is, the strobe lighting time can be reduced. Only the data of the image line that has been read out in the meantime can be obtained, and a good image of the object cannot be obtained. In the present invention, an object passing on the conveyance path reaches the reading portion by disposing a phosphorescence generating member that emits phosphorescence when receiving light irradiated from the light source between the reading portion of the conveying path and the CMOS image sensor. When the light source is turned on, phosphorescence is generated from the phosphorescence generating member. Since this phosphorescence continues to be generated for a while even after the light source is turned off, an afterimage as a regular reflection image from the object is generated only for a predetermined time. Therefore, a good image of the object can be acquired by capturing the afterimage of the object with a CMOS image sensor. Even when a low-cost CMOS image sensor is used in this way, an object that is transported at high speed on the transport path can be captured as an image with almost no blur.

  Preferably, the optical filter further includes an optical filter that is disposed between the imaging device and the phosphorescence generating member and blocks a wavelength component of light generated by the light source. Thereby, even if the light generated by the light source passes through the phosphorescence generating member, the light is removed by the optical filter. For this reason, it is possible to prevent the light generated by the light source from entering the image sensor as noise, so that a better image of the object can be acquired.

  Preferably, the phosphorescence generating member emits phosphorescence having a wavelength component corresponding to the spectral sensitivity characteristic of the image sensor. As a result, phosphorescence having a wavelength component with good sensitivity to the image sensor is received by the image sensor, so that it is possible to suppress a decrease in S / N of the obtained image.

  At this time, it is preferable that the light source irradiates the reading portion with light including ultraviolet rays, and the phosphorescence generating member emits phosphorescence having a visible light wavelength component. The use of a light source that irradiates light including ultraviolet rays is effective in reading an image of an object containing a component that fluoresces by ultraviolet rays. Further, since the visible light component is the wavelength component most suitable for the sensitivity of the CMOS image sensor, it is very effective for suppressing the S / N degradation of the image.

  Further, preferably, the imaging element captures an afterimage of the shadow of the object caused by phosphorescence. In this case, a clear image with a large contrast between a part other than the target object that causes phosphorescence and a target part that does not cause phosphorescence due to a shadow can be obtained. Can do.

  At this time, it is preferable to further include a diffusing plate that is disposed between the light source and the reading portion and diffuses the light emitted from the light source. Thereby, the diffused light with little illumination unevenness is irradiated to the phosphorescence generating member, so that a clearer image can be obtained between the part other than the object that generates phosphorescence and the object part that is shaded and does not generate phosphorescence. .

  According to the present invention, a phosphorescence generating member that emits phosphorescence when receiving irradiation light from a light source is disposed between a reading portion of a conveyance path and an imaging element, and an afterimage of an object generated by phosphorescence is captured by the imaging element. Thus, by using, for example, a CMOS image sensor as the image sensor, it is possible to obtain an object that is almost free of blurring while reducing the cost and conveying the object on the conveyance path.

  Hereinafter, a preferred embodiment of an image reading apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partially broken perspective view showing a first embodiment of an image reading apparatus according to the present invention. In the figure, an image reading apparatus 1 according to the present embodiment is an apparatus that reads an image such as a figure, a pattern, a number, and a character stamped on the surface of a coin 2. The image reading apparatus 1 has a rectangular parallelepiped housing 3, and a transparent plate 4 made of sapphire glass or the like is fixed to a circular opening provided in an upper plate 3 a of the housing 3. Yes.

  On the upper side of the housing 3, a transport device 5 that transports the coins 2 onto the transparent plate 4 is provided. The transport device 5 includes an endless belt 6 extending in the coin transport direction A, a pair of pulleys 7 for driving the endless belt 6, and a transport direction A of the coin 2 adjacent to the upper plate 3 a of the housing 3. And a transfer table 8 extending in the direction. The upper plate 3 a, the transparent plate 4, and the transport table 8 of the housing 3 form a transport path B for coins 2.

  As shown in FIGS. 1 and 2, an illuminating unit 9 that illuminates the coins 2 conveyed up to the transparent plate 4 is disposed at a position close to the transparent plate 4 inside the housing 3. The illuminating unit 9 is mounted on a ring-shaped printed circuit board 10, and a plurality of light sources 11 that irradiate light outward, and irradiation light (one-dot chain line in FIG. 2) from each light source 11 are transparent plates 4. And a ring-shaped reflecting plate 12 that reflects toward the reading portion 4a. The light source 11 is an ultraviolet LED that generates light including ultraviolet rays.

  In addition, a CMOS (Complementary Metal Oxide Semiconductor) image sensor 14 that images the coin 2 that has reached the reading portion 4 a on the transparent plate 4 via the lens system 13 is positioned below the illumination unit 9 inside the housing 3. Is arranged. The illumination unit 9 is configured such that, when the surface of the coin 2 is illuminated, only the light reflected by the edge 2a formed by the marking on the surface of the coin 2 proceeds in the direction toward the CMOS image sensor 14. .

  A flat phosphorescent glass 15 is disposed between the transparent plate 4 and the printed board 10. The phosphorescent glass 15 is a glass that emits phosphorescence P having a wavelength component different from that of the light generated by the light source 11 when receiving irradiation light from the light source 11. Phosphorescence refers to light that is generated once and continues to be emitted for a while after the light source 11 is turned off (see FIG. 4).

  By providing such a phosphorescent glass 15, the above-described CMOS image sensor 14 captures an afterimage of the coin 2 generated by the phosphorescence P, not a direct reflection image of the coin 2 by the irradiation light from the light source 11. Here, the phosphorescent glass 15 is desirably formed of a material that emits phosphorescence P having a wavelength component suitable for the spectral sensitivity characteristic of the CMOS image sensor 14, specifically, a visible light component. Thereby, since the light receiving sensitivity of the CMOS image sensor 14 becomes high, it is possible to suppress a decrease in S / N of an image obtained by imaging.

  Further, an ultraviolet removal filter 16 is disposed between the CMOS image sensor 14 and the lens 13. Thereby, even if the ultraviolet rays irradiated from the light source 11 pass through the phosphorescent glass 15, the ultraviolet rays are blocked by the ultraviolet ray removing filter 16 and are not incident on the CMOS image sensor 14 as noise. Accordingly, since the CMOS image sensor 14 receives only the phosphorescence P generated by the phosphorescent glass 15, it can be prevented that the image obtained by the imaging is adversely affected.

  Further, the image reading apparatus 1 has an arrival detection sensor 17 that detects whether or not the coin 2 has been conveyed to the reading portion 4 a on the conveyance path B by the conveyance device 5. The arrival detection sensor 17 is disposed above the housing 3 with two light emitting elements (for example, LEDs) 18 disposed inside the housing 3, and is emitted from each light emitting device 18 and passes through the transparent plate 4. It has two light receiving elements (for example, photodiodes) 19 for receiving light, and when it is detected that the coin 2 has been transported to the reading portion 4a, a predetermined pulse signal is transmitted (see FIG. 4A). ).

  Further, the image reading apparatus 1 has a light source control unit 20 as shown in FIG. When the pulse signal from the arrival detection sensor 17 is input, the light source control unit 20 controls each light source 11 to be lit for a predetermined time (see FIG. 4B). Here, the lighting time of each light source 11 is set to a time (for example, 200 μs) in which an image of the coin 2 that has been transported at high speed on the transport path B can be captured.

  In the image reading apparatus 1 configured as described above, when the coin 2 transported on the transport path B by the transport device 5 reaches the reading portion 4a, each light source 11 is pulsed and the surface of the coin 2 is instantaneously touched. Illuminated. At this time, the light emitted from each light source 11 is reflected by the surface of the coin 2, and when the reflected light reaches the phosphorescent glass 15, phosphorescence P is generated from the phosphorescent glass 15. As shown in FIG. 4C, this phosphorescence P continues to be emitted from the phosphorescent glass 15 for a predetermined time (for example, about 20 mS) even after each light source 11 is turned off. For this reason, an afterimage as a regular reflection image of the coin 2 remains between the phosphorescent glass 15 and the CMOS image sensor 14 for a while. Then, an afterimage of the coin 2 is picked up by the CMOS image sensor 14.

  The CMOS image sensor 14 is a so-called line-sequential readout type image pickup device that reads out an image for each scanning line. However, when the image of the coin 2 is picked up, while the images of all the scanning lines are read out, Since the afterimage of the still image of the coin 2 remains, a normal image with almost no blur can be acquired.

  At this time, as described above, if an image of the directly reflected light of the edge 2a formed on the surface of the coin 2 is picked up, the light reflected by the edge 2a and traveling toward the CMOS image sensor 14 is straight, and thus phosphorescent. The light of only the image information of the coin 2 efficiently passes through the phosphorescent glass 15 that generates P. For this reason, an afterimage generated by phosphorescence P can also be obtained as an image comparable to a direct reflection image as captured by a CCD camera, for example.

  As described above, the image data of the coin 2 obtained by the CMOS image sensor 14 is subjected to predetermined image processing by an image processing unit (not shown). The data after the image processing is sent to an identification processing unit (not shown), and processing such as authenticity determination of the coin 2 is executed by the identification processing unit.

  As described above, according to the present embodiment, even when an inexpensive CMOS image sensor 14 is used, by using phosphorescence (phosphorescence), the coin 2 that is conveyed at high speed on the conveyance path B is used. The edge image can be read as a still image with almost no blur. As a result, the cost of the image reading apparatus 1 can be reduced. Further, by using the CMOS image sensor 14, the circuit scale can be reduced, and the image reading apparatus 1 can be downsized.

  FIG. 5 is a block diagram showing a second embodiment of the image reading apparatus according to the present invention. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, an image reading apparatus 30 according to the present embodiment includes a plurality of light sources 31 that are disposed above a housing 3 and irradiate light onto a reading portion 4 a on a transparent plate 4. These light sources 31 are controlled in the same manner as described above by the light source control unit 20 (see FIG. 3). Between the plurality of light sources 31 and the reading portion 4a, a diffusion plate 32 for diffusing the irradiation light from each light source 31 is disposed. The phosphorescent glass 15 is fixed to the lower surface of the transparent plate 4. Other configurations are the same as those of the image reading apparatus 1 in the first embodiment.

  When the coin 2 transported on the transport path B comes to the reading portion 4a, each light source 31 is pulse-lit, and the light from each light source 31 is irradiated to the diffusion plate 32. The light irradiated on the diffusion plate 32 becomes the diffused light Q with little illumination unevenness, and instantaneously illuminates the coin 2 and the phosphorescent glass 15. Thereby, phosphorescence P is generated from the phosphorescent glass 15, and an afterimage of the phosphorescence P is captured by the CMOS image sensor 14.

  At this time, the portion corresponding to the coin 2 in the phosphorescent glass 15 is not irradiated with the diffused light Q, so that only that portion becomes a shadow, and the other portion emits phosphorescence P to become bright and become an afterimage. When such an afterimage of phosphorescence P is imaged, as shown in FIG. 6, the captured image includes a portion other than the coin 2 that generates phosphorescence P and a portion of coin 2 that does not generate phosphorescence P in the shadow. A clear shadow image with high contrast can be obtained. This makes it possible to determine the outer diameter of the coin 2 with high accuracy.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the phosphorescent glass 15 that emits the phosphorescence P of the visible light component is used. However, for example, a phosphorescent glass that emits the phosphorescence of the infrared light component may be used.

  Moreover, in the said embodiment, it was set as the structure which images the coin 2 with the CMOS image sensor 14, However As a cheap image pick-up element which images the coin 2, in addition to a CMOS image sensor, a photodiode array type image sensor etc. May be used.

  Moreover, although the image reading apparatus of the said embodiment reads the image of the coin 2, this invention is applicable also to the medal, a card | curd, etc. with which the stamp was provided on the surface.

1 is a partially broken perspective view showing a first embodiment of an image reading apparatus according to the present invention. It is sectional drawing which shows the internal structure of the housing | casing shown in FIG. It is a figure which shows the control system structure of the light source shown in FIG. It is a timing diagram which shows the relationship between lighting of the light source shown in FIG. 1, and light emission of phosphorescent glass. It is a block diagram which shows 2nd Embodiment of the image reading apparatus which concerns on this invention. It is a figure which shows the picked-up image by the CMOS image sensor shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image reading device, 2 ... Coin (object), 3 ... Housing, 3a ... Upper plate, 4 ... Transparent plate, 4a ... Reading part, 8 ... Conveyance table, 11 ... Light source, 14 ... CMOS image sensor (Imaging) Element), 15 ... phosphorescent glass (phosphorescence generating member), 16 ... ultraviolet light removal filter (optical filter), 17 ... sensor for arrival detection (arrival detection means), 20 ... light source control unit (light source control means), 30 ... image reading Device 31 ... Light source 32 ... Diffuser plate B ... Transport path P ... Phosphorescence

Claims (6)

In an image reading apparatus that reads an image of an object passing on a conveyance path,
A light source for irradiating light to a reading portion of the conveyance path;
A light source control means for controlling the light source to be lit for a predetermined time when the object is conveyed to the reading site;
An image sensor that images the object when the object is transported to the reading site;
A phosphorescence generating member that is disposed between the reading portion and the imaging element and emits phosphorescence upon receiving irradiation light from the light source;
The image reading device, wherein the image pickup device picks up an afterimage of the object generated by the phosphorescence.   The image reading apparatus according to claim 1, further comprising an optical filter that is disposed between the imaging element and the phosphorescence generating member and blocks a wavelength component of light generated by the light source.   The image reading apparatus according to claim 1, wherein the phosphorescence generating member emits phosphorescence having a wavelength component corresponding to a spectral sensitivity characteristic of the image sensor. The light source irradiates the reading part with light including ultraviolet light,
4. The image reading apparatus according to claim 3, wherein the phosphorescence generating member emits phosphorescence having a visible light wavelength component.   The image reading apparatus according to claim 1, wherein the image pickup device picks up an afterimage of a shadow of the object generated by the phosphorescence.   The image reading apparatus according to claim 5, further comprising a diffusion plate that is disposed between the light source and the reading portion and diffuses light emitted from the light source.

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