JPH08329179A - Mark detector - Google Patents

Abstract

PURPOSE: To obtain high detection accuracy by diverging light generated from plural light sources also in the width direction in addition to the longitudinal direction by using a cylindrical lens with the same cross-sectional shape and forming a thin band-like light irradiation area. CONSTITUTION: A light irradiation part 12 is constituted of so as to discharge light converged like a thin band in the width direction of a lens 17 through an aperture part by straight arranging plural light emitting elements 26 with prescribed intervals along the longitudinal direction of the aperture part and arranging a cylindrical lens 17 close to a light discharging part 16. Since respective light emitting elements 26 are arranged right-and-left symmetrically about the center of the longitudinal direction so that their intervals are wide on the center part and gradually narrowed in the peripheral direction, light quantity on both the side parts is increased and the intensity of light as even as possible can be secured approximately over the whole light irradiated face 13. Consequently a mark can be detected at high accuracy regardless of a slight deviation between optical axes 32, 33 or variation in a distance front a reference position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a mark such as a bar code with a plurality of point light sources to irradiate a strip of light and detects the light emitted from the light irradiation position to detect the mark. The present invention relates to a mark detection device for determining the information content of, and particularly to a configuration for forming a strip-shaped irradiation light.

[0002]

2. Description of the Related Art Conventionally, a mark detecting device of this type is generally one that irradiates light linearly by narrowing light emitted from a plurality of point light sources as much as possible in the width direction using a cylindrical lens. It was In such a condensing type, the intensity of the light irradiated on the mark can be set as large as possible, but on the other hand, the optical axes of the light irradiation system and the detection system must be exactly aligned. When the surface to be detected shifts from, the use condition is limited such that the detection output is extremely reduced.

On the other hand, instead of narrowing down the light emitted from the light source, the columnar lens 1 is arranged by arranging the light source 15 at the focal position of the columnar lens 17 as shown in FIG.
By making it possible to form the strip-shaped light irradiation region 13a by emitting parallel light from 7, the irradiation light intensity on the mark is slightly lowered, but it is sufficient even if the optical axes of the irradiation system and the detection system are slightly deviated. A device capable of obtaining a light detection output has also been proposed.

By the way, as the conventional reflection type bar code used for the above-mentioned mark detection, a printing ink containing carbon black is generally used, and there are a part where the bar code is printed and a part where the bar code is not printed. By utilizing the difference in light reflectance, the code information of the barcode is read. Since such a reflective barcode is printed on the surface of a product or the like, the appearance of the product may be impaired, and if the printed surface becomes dirty, the difference in reflectance may become small and a reading error may occur. .

In order to solve such inconvenience, the applicant of the present invention has previously printed a bar code by using an invisible ink containing a phosphor and irradiating the latent image state mark with light in the infrared region, while irradiating light. We proposed a light emitting barcode that detects fluorescence in the infrared region generated from the position.

[0006]

However, in principle, the light emitting bar code described above has a light intensity that can be extracted from the surface to be detected as small as several tens of minutes as compared with the reflective bar code. It is known that in the light irradiation using the parallel light, the detection intensity of the light is still greatly reduced when the light beam is out of the coincidence point of the optical axes, and the degree of freedom of the light irradiation position cannot be increased. Especially when this kind of device is applied to a handy type scanner, it is difficult for the operator himself to set the mark reading position, so it is difficult to always keep the distance between the mark and the scanner constant. A large detector is desired.

In response to such a demand, it is possible to increase the absolute value of the irradiation light intensity by increasing the number of light sources or the emission intensity itself, but this method causes a large increase in manufacturing cost. At the same time, the current consumption of the light source is increased and the life of the light source is shortened, which is very inconvenient for this type of scanner. However, it has been considered that it is extremely difficult to increase the degree of freedom of the light irradiation position without increasing the light intensity of the light source.

As a result of various experiments conducted by the present inventors to eliminate the above-mentioned inconvenience, as shown in FIG. 4 (d), the light source 15 is brought closer to the columnar lens 17 side than the focal position, and the irradiation light is slightly changed. It was found that, when the light is diverged, contrary to the conventional wisdom that was considered to simply reduce the intensity of the irradiation light to the surface to be detected, the degree of freedom of the irradiation position of the light is rather increased.

A more detailed experiment was conducted to find that the result opposite to the conventional common sense was obtained.
In the conventional parallel light type shown in (d), the light emitted from the plurality of light sources 15 is converged in the width direction by the cylindrical lens.
As shown in (c), the light emitted from the light sources 15 interferes with each other as a result of direct divergence in the longitudinal direction, resulting in periodic fluctuations in the irradiation light intensity along the longitudinal direction of the light irradiation region 13a. It was.

Incidentally, FIG. 5 (b) is a diagram of 5 in FIG. 5 (c).
It is the figure seen in the -5 line direction, and the range which exceeds the light intensity set up beforehand is shown as the shaded area as the light irradiation area 13a.
Further, FIG. 5A shows a change in light intensity at a position along the line BB in FIG. 5B. Figure 5 (a)
It has been confirmed that the variation in the amount of light on the surface to be detected as shown in (b) still occurs when the number of light sources 15 is increased and the intervals between the light sources 15 are narrowed. It is judged that this is an essential problem in the irradiation light.

On the other hand, in the case of the divergent light type shown in FIG. 4, which is shown in comparison with FIG. 5, the interference between the light beams emitted from the respective light sources 15 is reduced, and the light beams shown in FIGS. It has been confirmed that a substantially uniform light amount can be obtained over the entire light irradiation region 13 while maintaining a sufficiently large light amount. That is, when the light is condensed by the columnar lens 17 as in the conventional case, the maximum value of the light amount in the light irradiation region 13a increases, but the minimum value also decreases and the light amount varies, whereas the light source 15 is focused. When the light is closer to the lens and slightly diverged, the light generated from the light source 15 is effectively passed through the lens to increase the total amount of light that can be used for light irradiation, while maintaining the variation in the light amount that has been conventionally present. A smooth and substantially uniform light intensity was achieved over the entire light irradiation region 13.

In the case of the reflection type mark, since the mark portion is determined according to the reflectance ratio between the mark portion and the ground portion, the intensity of the irradiation light is slightly lowered. However, the reflectance ratio itself does not change, and the necessary contrast is secured. On the other hand, in the case of the light emitting type mark, the method is to judge in accordance with the ratio of the amount of light emission to the noise component in the mark portion, that is, the SN ratio, and if the intensity of the irradiation light decreases, the amount of light emission decreases proportionally. On the other hand, since the noise component hardly changes, the SN ratio also decreases, and the reduction in the irradiation light amount has a great influence on the reduction in mark detection accuracy as compared with the reflection type.

That is, in the reflection type mark, the reflection state of the surface to be detected affects the detection accuracy rather than the irradiation light intensity, whereas in the light emitting type mark, the minimum value of the irradiation light intensity is detected. The accuracy is greatly affected, and the light irradiation range where the mark can be detected can be increased without increasing the absolute value of the light intensity emitted from the light source.

The present invention has been made on the basis of the above-mentioned findings. The light emitted from a plurality of light sources is diverged not only in the longitudinal direction but also in the width direction by using a columnar lens having the same sectional shape. By forming a strip-shaped light irradiation area by doing so, a mark detection device with high detection accuracy can be provided regardless of a slight deviation of the optical axis in the light irradiation system and the detection system or a change in the distance from the reference detection surface. The purpose is to provide.

[0015]

A mark detecting device according to the present invention has a strip-like shape across a mark 10 formed on an arbitrary medium, as schematically shown in FIG. A light irradiation unit 12 capable of irradiating light and a photoelectric conversion unit 14 that takes in the light emitted from the light irradiation region 13 on the medium and converts it into an electric signal are provided.

Further, the above-mentioned light irradiating section 12 has a plurality of point-like light sources 15 arranged in a straight line at predetermined intervals,
A columnar lens 17 continuously covering the light emitting portion 16 in the light source 15 in the longitudinal direction is provided, and the light incident on the columnar lens 17 is added to the columnar lens 17 in the longitudinal direction and in the width direction. It is characterized by being slightly diverged.

The columnar lens 17 has the function of a convex lens in its width direction, and the light source 1 described above is used.
It is preferable that the light emitting portion 16 of No. 5 is arranged closer to the lens 17 side than the focal position of the columnar lens 17. Further, the plurality of light sources 15 described above can be set such that the distance between the light sources 15 becomes smaller from the central portion toward the peripheral portion.

Further, the mark 10 described above is formed as a latent image in which the irradiation light in the infrared region emits fluorescence in the infrared region having a wavelength different from that of the irradiation light. Further, the point where the optical axis 32 of the light irradiation section 12 and the optical axis 33 of the photoelectric conversion section 14 intersect with each other is set as a reference position, and the mark 10 is provided before and after the reference position.
Is formed, and the intersection angle θ of the two optical axes 32 and 33 is restricted to the range of 10 to 30 °. The light irradiation unit 12 and the photoelectric conversion unit 14 described above are housed in a main body case 18 of a size that can be held by one hand, as shown in FIGS.

[0019]

With the above-described structure, when the apparatus is operated after setting the detected surface 11 at the reference position, first the light irradiation section 1
The light source 15 in FIG.
Light is incident on 7. Here, the columnar lens 17 transmits the incident light as it is in the longitudinal direction thereof, but takes out the light in a state in which it is slightly diverged from the parallel rays in the width direction, so that on the detected surface 11. , A strip-shaped light irradiation area 13 that maintains substantially the same light intensity over almost the entire area
Is configured. Therefore, the photoelectric conversion unit 14 captures the light generated from the surface to be detected 11 across the central portion of the light irradiation region 13 and converts the light into an electric signal corresponding to the intensity of the incident light.

Here, when the surface 11 to be detected is approached to or separated from the light irradiation unit 12 side from the reference position as shown by the chain double-dashed line, the detection position in the photoelectric conversion unit 14 becomes the light irradiation region 1
It shifts from the center in 3 in the width direction. However, since the light irradiation region 13 is configured to have a narrow width with a substantially constant light intensity, the detection operation of the mark 10 is performed in the same manner as in the reference position regardless of the slight deviation of the light detection position. To be seen.

[0021]

As described above, according to the present invention, the light generated from the plurality of light sources 15 uses the columnar lens 17 whose cross-sectional shape is substantially the same over the entire length thereof, and the light source 15 is moved from the focal position to the vertical lens 17. By arranging them closer to the side and slightly diverging the incident light not only in the longitudinal direction but also in the width direction, it is possible to form a light irradiation region 13 having a strip shape and the irradiation light intensity being substantially uniform over the entire region. The mark can be detected with high accuracy regardless of the slight deviation of the optical axes 32 and 33 in the light irradiation system and the detection system and the change in the distance from the reference position.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of carrying out the present invention in a portable scanner for detecting an invisible mark 10 which emits fluorescence upon irradiation with light in the infrared region, as shown in FIGS. However, it is needless to say that the present invention is not limited to this, and can be performed in substantially the same manner with respect to the one using the reflection of light on the mark.

[0023]

[Structure of Mark] The mark 10 has fluorescent fine particles made of a fluorescent substance that emits infrared rays having a wavelength different from that of the irradiation light in response to the irradiation of infrared rays, and has the property of transmitting infrared rays, It is composed of a binder that disperses and holds it, and is printed and formed on an arbitrary product instead of the conventional barcode, so that its shape is invisible to the naked eye.

As the fluorescent substance forming the mark 10,
For example, neodymium (Nd), ytterbium (Yb),
A rare earth element simple substance such as eurobium (Eu), thulium (Tm), praseodymium (Pr), and dysprosium (Dy), or a mixture thereof is used as an emission center, and these emission centers are fluoride, phosphate, molybdate,
It is preferable to form the oxide such as tungstate with an inorganic compound contained in the matrix.

In this embodiment, Li (Nd _O.9 Yb _O.1 ) P ₄
By forming and printing a fluorescent coating material containing an inorganic compound such as O ₁₂ , for example, when irradiated with excitation light in the near infrared region having a wavelength of around 800 nm, the infrared region having a peak value at a wavelength of around 1000 nm Even when the light irradiation is stopped, the decay time of 90 to 10% is 400 to 6
It is configured to generate an afterglow of about 00 μs.

Other inorganic compounds satisfying the above conditions include NdP ₅ O ₁₄ · LiNdP ₄ O ₁₂ ·.
There is NaY _0.69 Yb _0.3 Er _0.01 F ₄ . However, it is needless to say that the material can be changed as appropriate as long as it emits fluorescence by irradiating light with an arbitrary wavelength.

[0027] For example, an inorganic compound represented by the general formula of the _{"Ln 1-xy Nd x Yb y} Z " can also be used. Note that Ln in the formula is Bi, Ge, Ga, Gd, In, La, Lu,
Represents one or more elements selected from the group Sb, Sc, Y.

Further, Z in the formula is A ₅ (MO ₄ ) ₄ · D ₃ (B
O ₃ ) ₄ · P ₅ O ₁₄ · A ₃ (PO ₄ ) ₂ · Na ₂ Mg ₂ (V
It is selected from the group of O ₄ ) ₃ · A ′ (MO ₄ ) ₂ . In addition, A is one or more elements selected from the group K / Na, M is one or more elements selected from the group W / Mo, and D is one or more elements selected from the group Al / Cr. Element, A'represents one or more elements selected from the group of Li.K.Na.

X and y in the formula are numerical values in the range of 0.25≤x≤0.99 and 0.11≤y≤0.75 when Z is A ₅ (MO ₄ ) ₄ described above. , Z is D ₃ (B
When O ₃ ) ₄ , 0.10 ≦ x ≦ 0.99 and 0.01
Numerical value in the range of ≦ y ≦ 0.90, when Z is P ₅ O ₁₄ , 0.05 ≦ x ≦ 0.98 and numerical value in the range of 0.02 ≦ y ≦ 0.95, Z is A ₃ ( 0.02 if PO ₄ ) ₂
≦ x ≦ 0.98 and a numerical value in the range of 0.02 ≦ x ≦ 0.98, and when Z is Na ₂ Mg ₂ (VO ₄ ) ₃ , 0.57 ≦
Numerical value in the range of 0.01 ≦ y ≦ 0.43 when x ≦ 0.90,
When Z is A ′ (MO ₄ ) ₂ , 0.20 ≦ x ≦ 0.9
5 is selected from the range of 0.05 ≦ y ≦ 0.80.

Specifically, Nd _0.8 Yb _0.2 Na ₅ (W
O ₄ ) ₄ · Nd _0.9 Yb _0.1 Na ₅ (Mo ₄ ) ₄ · Y _0.1 Nd
_0.75 Yb _0.15 (WO ₄ ) ₄・ Nd _0.8 Yb _0.2 Na ₅ (Mo
_0.5 W _0.5 O ₄ ) ₄・ Bi _0.1 Nd _0.75 Yb _0.15 K ₅ (MoO
₄ ) ₄・ La _0.1 Nd _0.8 Yb _0.1 (Na _0.9 K _0.1 ) ₅ (WO
₄ ) ₄ · Nd _0.9 Yb _0.1 Al ₃ (BO ₃ ) ₄ can be used.

Furthermore, the general formula _{"EF 1-xy Nd x Yb y} P 4 O
_An inorganic compound represented by ₁₂ "can also be used. E in the formula is 1 selected from the group of Li, Na, K, Rb, and Cs.
More than one element, F is Sc, Y, La, Ce, Gd, Lu
Represents one or more elements selected from the group of Ga, In, Bi, and Sb. Further, x and y in the formula are
0.05 ≦ x ≦ 0.999 and 0.001 ≦ y ≦ 0.
It is a numerical value in the range of x + y ≦ 1.0 at 950. Specifically, LiNd _0.9 Y _0.1 P ₄ O ₁₂ · LiBi _0.2 Nd _0.7 Y
_0.1 P ₄ O ₁₂ · NaNd _0.9 Y _0.1 P ₄ O ₁₂ can be used.

Furthermore, oxygen-containing salts such as phosphates, borates, molybdates, and tungstates containing Yb and at least one element selected from the group of Y.La.Gd.Bi. , Specifically, the general formula “A (Y, L
a, Gd, Bi) _x Yb _1-x P _y O _z ”can also be used. A in the formula is Li, Na, K, Rb,
One or more elements selected from the group of Cs and not necessarily required. Further, x is a numerical value in the range of 0.01 to 0.99, y is a numerical value in the range of 2 to 5, and z is a numerical value in the range of 7-14.

As the binder, a solventless type such as an ultraviolet curable resin, a solvent type such as polyurethane,
Alternatively, any water-soluble type such as polyvinyl alcohol (PVA) can be used, and it is appropriately selected depending on the printing method and the material of the detection target. Further, if necessary, a plasticizer, a surfactant and the like are appropriately added.

The content of the phosphor fine powder is preferably 10 to 80% by weight, and more preferably 25 to 70% by weight. Marked as containing less than 10% by weight of fine phosphor powder
If the light emission output is too weak, on the contrary, if it exceeds 80% by weight, the mark 10 may be peeled off because printing is difficult and the adhesive strength is weak.

[0035]

[Structure of Scanner] A scanner for detecting the mark 10 has a detailed structure as shown in FIGS.
Inside the main body case 18, a light irradiation unit 12 that can irradiate the mark 10 with predetermined light, a photoelectric conversion unit 14 that takes in fluorescence generated from a light irradiation position and converts the fluorescence into an electric signal, and each unit. Mark 10 while controlling the operation timing
Control unit 19 for extracting a mark signal corresponding to the formation position of the
The signal cable 39 is extended from the control unit 19 to the outside of the main body case 18 and a mark signal is input to a personal computer (not shown) to enable substantially the same signal processing as in the related art.

The main body case 18 is a combination of an upper case 20 and a lower case 21 in a lid-matching manner, and a handle 22 of a size that can be grasped by one hand is formed in a central portion thereof, and the handle 22 is directed toward the tip thereof. A detection head 24 is formed in which the lateral width is enlarged and is bent obliquely downward, and the opening 23 is provided in the tip end surface. The opening 23 has a horizontally long rectangular shape whose lateral length is slightly larger than the length of the mark 10 to be detected, and is provided with a mud 40 capable of transmitting at least infrared light and is closed by a frame 25. This prevents dust from entering the main body case 18.

As shown in FIGS. 1 and 3, the light irradiating section 12 has a plurality of light emitting elements 26 arranged in a straight line along the longitudinal direction of the opening section 23 at a predetermined interval, and the light emitting section 16 thereof. By arranging the columnar lenses 17 in close proximity to each other, the light narrowed down in the width direction of the columnar lenses 17 into a narrow band is emitted through the opening 23.
The present invention is characterized by the configuration of the light irradiation section 12, and the details will be described later.

The photoelectric conversion unit 14 takes in the light emitted from the mark 10 irradiated by the light irradiation unit 12 in a substantially vertical direction into the main body case 18 through the opening 23, and then, the direction thereof is reflected by the mirror 27. Of the light-receiving element 3 having the image forming lens 28 and an optical filter 29 on the front surface thereof.
It is configured to form an image on the image plane 0, and each component thereof is fixed on the frame 31 to form a unit.

As the optical filter 29, for example, a single crystal substrate of indium phosphide (InP) is used, which blocks infrared light having a wavelength emitted from the light irradiating section 12 and selects infrared light having a wavelength emitted from the mark 10. And then transmitted to the light receiving element 30.

Like the CCD or photodiode array, the light receiving element 30 takes in the fluorescence emitted from the surface 11 to be detected, electrically scans it, and converts it into an electric signal of a magnitude corresponding to the intensity of the incident light. What can be used.

In the present embodiment, the position of the detection object in the image forming lens 28, which is in the best image forming state, is the light irradiating section 12.
Is set at a position approximately 3 cm from the light emitting portion 16 of the light emitting element 26, and further, at a position which crosses the substantially center of the light irradiation region 13 by the irradiation light as shown in FIG. By intersecting the axis 32 and the optical axis 33 of the imaging lens 28 at about 15 °, and using that as the reference position, for example, by setting the depth of field deep in the range of 1 cm or more in the front and rear, Even if the reference position is slightly approached or separated from the reference position, or the detected surface 11 itself is corrugated and the distance from the reference position is varied, the output fluctuation from the light receiving element 30 may be varied. I try to be suppressed as much as possible.

By setting the intersection angle θ as small as possible, the fluctuation of the output signal from the photoelectric conversion unit 14 can be set small regardless of the depth of field of the apparatus as a whole, that is, the distance from the reference position. However, it is preferably selected from the range of 10 ° to 30 ° in consideration of the dimensions of various optical system components or the positional relationship in arrangement. Further, it is needless to say that the depth of field of the photoelectric conversion unit 14 itself can be appropriately changed according to the use conditions of the device, changes in the configuration, and the like.

The control section 19 is provided with a push button switch 34 on the lower surface side of the handle 22 in the main body case 18,
The light irradiation unit 12 and the photoelectric conversion unit 14 described above are operated in conjunction with the pressing operation of the switch 34.

The present invention is characterized by the structure of the light irradiation section 12 described above, and as shown in FIGS. 3 and 4, generates near infrared rays having an emission center wavelength of around 800 nm on the printed circuit board 35. Six light emitting elements 26 are fixed in a straight line. The light emitting elements 26 are arranged symmetrically with respect to the center in the longitudinal direction, and the intervals are set such that the central portion is wide and the peripheral portions are narrower, so that the irradiation light overlaps. The amount of light is increased in both side portions where there is less light so that the light intensity is as uniform as possible over substantially the entire light irradiation surface.

As shown in FIG. 1B, the light emitting element 26 has a flat cylindrical case 36 having a light emitting portion 16 on the front side thereof, and a light emitting diode chip fixed on the bottom surface inside the case 36. And a point-like light source 15 such as
The light emitted from the light source 15 is emitted to the outside of the case 36 while the light emitting portion 16 regulates the scattering direction.

The lens 17 arranged close to the light emitting portion 16 of the light emitting element 26 has a columnar shape whose cross section is substantially semi-circular and is the same in the longitudinal direction. By aligning the light source 15 with the array position of the light sources 15 and arranging the light sources 15 slightly ahead of the focal position of the columnar lens 17, the light incident from the light emitting element 26 to the back surface 37 side of the columnar lens 17 can be changed. The light is emitted from the front surface 38 side of the lens 17 while being slightly diverged by 17.

In this embodiment, the columnar lens 17 having the function of a convex lens having a focal point at a position 5 mm from the back surface 37 of the columnar lens 17 in its width direction is used, while the light source 15 in the light emitting element 26 is columnar. Back side 3 of lens 17
The distance is from 7 to 2 mm. With this configuration,
Even in the light irradiation area 13 facing the side edge position of the columnar lens 17 shown by AA in FIG. 4B, it is sufficient for mark detection and substantially uniform over the entire area as shown in FIG. It was confirmed that various light intensities were obtained.

The columnar lens 17 can be made to diverge incident light by using a concave lens function instead of a convex lens function, and by moving it slightly away from the focal position. Further, instead of making the entire device a handy type, it may be a fixed type.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of the present invention.

FIG. 2 is a partially cutaway plan view showing an example in which the present invention is applied to a portable scanner.

3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 is an explanatory diagram showing a light irradiation state in a light irradiation unit.

5 is an explanatory diagram showing a light irradiation state similar to FIG. 4 in a conventional example.

[Explanation of symbols]

 10 mark 11 surface to be detected 12 light irradiation section 13 light irradiation area 14 photoelectric conversion section 15 light source 16 light emission section 17 columnar lens 18 main body case 19 control section 20 upper case 21 lower case 22 handle 23 opening 24 detection head 25 frame 26 light emitting element 27 mirror 28 imaging lens 29 optical filter 30 light receiving element 31 frame 32 optical axis of light irradiation section 33 optical axis of photoelectric conversion section 34 switch 35 printed circuit board 36 case of light emitting element 37 back surface of lens 38 front surface of lens 39 Signal cable 40 mad

Claims (6)

[Claims] 1. A mark (1) formed on an arbitrary medium.
0) including a light irradiation portion (12) capable of irradiating the surface to be detected (11) in the form of a strip, and a light irradiation region (1) on the surface to be detected (11) described above.
3) a photoelectric conversion part (14) for taking in light emitted from the device and converting it into an electric signal, and the above-mentioned light irradiation part (12) is provided with a plurality of points arranged in a straight line at predetermined intervals. A light source (15) and a columnar lens (17) continuously covering the light emitting portion (16) of the light source (15) in the longitudinal direction, and the light incident on the columnar lens (17) is provided. A mark detecting device characterized in that the columnar lens (17) is slightly diverged in the width direction. 2. The columnar lens (17) has a function of a convex lens in the width direction, and the light emitting portion (16) of the light source (15) is focused on the columnar lens (17). The mark detection device according to claim 1, wherein the mark detection device is disposed closer to the lens side than the position. 3. The mark detecting device according to claim 2, wherein the plurality of light sources (15) are set such that the distance between the light sources (15) becomes smaller from the central portion toward the peripheral portion. 4. The mark detection device according to claim 3, wherein the mark (10) is formed as a latent image which emits fluorescence in an infrared region having a wavelength different from that of the irradiation light by the irradiation light in the infrared region. 5. The optical axis (3) of the above-mentioned light irradiation section (12).
The readable range of the mark (10) is formed on the basis of the intersection of the optical axis (33) of the photoelectric conversion unit (14) with the optical axis (33) of the photoelectric conversion unit (14), and the intersection of the two optical axes (32) and (33). Angle θ is 10
The mark detection device according to claim 4, wherein the mark detection device is regulated within a range of -30 °. 6. The mark detection device according to claim 5, wherein the light irradiation section (12) and the photoelectric conversion section (14) are housed in a main body case (18) having a size that can be held by one hand. .