JP2676938B2 - Bar code reader protection plate and bar code reader - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bar code reader protective plate and a bar code reader of a bar code reader.

[Prior Art] Glass is used for a barcode reading portion of a barcode reader. Since the barcode is optically read, the reading part must have a high transmittance for light in the visible wavelength range, and it can be strongly rubbed or pressed by a product with a barcode. Therefore, the reading unit must be hard and difficult to be scratched. Normally, float glass is used, but air-cooled or chemically strengthened glass may be used for the purpose of improving scratch resistance and crack strength. Among the above reasons, the fact that scratches are unlikely to occur is particularly important because the transmittance is reduced due to the scattering of transmitted light due to the scratches, which causes improper reading or improper reading. Since the scratch resistance of the glass itself is insufficient in terms of scratch resistance,
The glass surface is coated with a film of titania (TiO ₂ ) or tin oxide (SnO ₂ ) by a dip or spray method to improve scratch resistance.

[Problems to be Solved by the Invention] However, the scratch resistance of the above-mentioned protective films such as TiO ₂ and SnO ₂ was not sufficient. For example, in bar code readers used in grocery stores, the glass is rubbed by a hard object such as a glass bottle or can with a bar code. The glass had to be changed once.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and at least one of Zr, Ti, Hf, Sn, Ta and In and B is formed on a transparent substrate. A protective plate for a bar code reading part, which has a scratch-resistant protective film made of an amorphous oxide film containing an oxide containing (boron) and at least one of Si (silicon) as a main component. And on the transparent substrate, Zr, Ti, Hf, Sn, T
A scratch-resistant protective film formed of an amorphous oxide film containing an oxide containing at least one of a and In and at least one of B (boron) and Si (silicon) as a main component is formed. The present invention also provides a bar code reader having a protective plate for a bar code reading unit.

FIG. 1 shows a schematic sectional view of an example of a protective plate of a bar code reading unit of the present invention.

The transparent substrate 2 used in the present invention is a soda-lime glass, a borosilicate glass, a lead silicate glass, an aluminosilicate glass, an aluminoborosilicate glass, a quartz glass, a barium borate glass, or the like. You may have one. Alternatively, a plastic substrate or a film can be used. The shape of the substrate is not limited to a flat plate, but may be a bent shape or any other shape. From the viewpoint of safety, in the case of a glass substrate, it is preferable that the glass substrate be strengthened by air cooling and chemical strengthening, and that the glass fragments be prevented from scattering at the time of destruction by combination.

The present invention provides an amorphous oxide film containing at least one of Zr, Ti, Hf, Sn, Ta, and In and an oxide containing at least one of B and Si as a main component. It has been found out that the thin film is excellent in abrasion resistance and chemical durability, and is characterized in that such a film is used as the scratch-resistant protective film 1.

Table 1 shows properties of various amorphous oxide films suitable as the scratch-resistant protective film 1 in the present invention. Films were formed by reactive sputtering using targets having the compositions shown in the table. Even if the same target is used, the film composition and the refractive index may vary slightly depending on the film forming conditions, and therefore Table 1 is merely an example.

The crystallinity was observed by thin film X-ray diffraction. The abrasion resistance is the result of a rubbing test with a sand eraser rubber. ○ indicates that the scratch was hardly formed, and X indicates that the scratch was easily generated.

Abrasion resistance was measured using the Taber test (wear wheel CS-10F, weight 500
g, 1000 rotations), those with a haze of 4% or less were evaluated as ○, and those with a haze of more than 4% were evaluated as x. The acid resistance was evaluated by immersing in 0.1NH ₂ SO ₄ for 240 hours, and when the change rate of T _V (visible light transmittance) and R _V (visible light reflectance) from before immersion was within 1%, 4% was evaluated as Δ, and the film dissolved and disappeared was evaluated as ×. Alkali resistance is 240 in 0.1N NaOH
As a result of time immersion, the rate of change of T _V and R _V before immersion is 1
%, And those in which the film was dissolved were evaluated as x. Boiling test, one atmosphere, was immersed for 2 hours in 100 ° C. water, when T _V, the rate of change for the previous immersion R _V is within 1% ○, and as × when 1 percent.

In the scratch-resistant protective film 1 of the present invention, the content ratio of boron or silicon is not particularly limited, but the following range is preferable.

As is clear from Table 1, the ZrB _x O _y film tends to form a crystalline film when the amount of B in the film is small, and to form an amorphous film when the amount of B is large. It can be seen that a crystalline film is inferior in scratch resistance and abrasion resistance, whereas an amorphous film is excellent. This is presumably because the amorphous film has a smooth surface. Therefore, the ZrB _x O _y film (the atomic ratio x of B to Zr in the film is 0.10 <x) is excellent in scratch resistance and abrasion resistance. Since B ₂ O ₃ is hygroscopic and absorbs and dissolves moisture in the air, it is preferable that x ≦ 3 in the ZrB _x O _y film.

The atomic ratio of O (oxygen) to Zr in the ZrB _x O _y film is not particularly limited, but if it is too large, the film structure becomes rough and the film becomes a messy film. Therefore, it is preferable that the amount is a composite system of ZrO ₂ and B ₂ O ₃ for the reasons that the transmittance is lowered and the scratch resistance of the film tends to be lowered. That is, the composite oxide is converted to ZrO ₂
When expressed as + xBO _1.5 , it is preferable that y = about 2 + 1.5x when B is contained at an atomic ratio of Zr to x.

Also, from Table 1, as the amount of B in the ZrB _x O _y film increases,
It can be seen that the refractive index of the film tends to decrease. By increasing B in the film, the refractive index n decreases from about 2.0 to about 1.5.

Therefore, a ZrB _x O _y film having 0.10 <x ≦ 3,2 <y ≦ 6.5 has good scratch resistance and abrasion resistance, and the refractive index can be freely selected depending on the amount of B according to the present invention. It is a suitable scratch-resistant protective film.

Furthermore, as shown in Table 1, as the content of B in the film increases, the acid resistance and alkali resistance tend to deteriorate. When x ≧ 2.3, the acid resistance deteriorates, and when x ≧ 4, the alkali resistance decreases and the boiling test shows deterioration. Therefore, when high chemical durability is required, ZrB _x O _y (x
The amorphous oxide film of <2.3) is preferable.

As described above, it is considered that the addition of B to the ZrO ₂ film makes the film amorphous and smoothes the surface, which contributes to the improvement of wear resistance and scratch resistance. In addition, the refractive index can be adjusted by the amount of B, and further, compared with the ZrO ₂ film,
Substrate (glass, plastic et
This is advantageous from the viewpoint of c) and adhesion to the underlying film on the substrate. This is particularly advantageous when forming a thick film.

Next, with respect to the ZrSi _z O _y film, a film which is also amorphous and has high scratch resistance and abrasion resistance can be obtained.

Regarding the refractive index, ZrO ₂ (n = 2.15) and SiO ₂ (n = 1.
46) It fluctuates depending on the composition ratio.

In the ZrSi _z O _y film, 0.05 ≦ z (Si with respect to Zr in the film)
Is preferably 19 or less. If z <0.05,
The film does not become amorphous, and sufficient physical durability cannot be obtained.
If z> 19, the alkali resistance is poor. Also, y (Zr
For the same reason as described for the ZrB _x O _y film, the atomic ratio of O to Zr in the Si _z O _y film is about y = 2 + 2z when Si is included in the atomic ratio to Zr. Preferably there is.

Therefore, when high durability is required, 0.05 ≦ z ≦ 1
A ZrSi _z O _y film with 9,21 ≦ y <40 is preferable.

Further, a ZrB _x Si _z O _y film is also a suitable film as a scratch-resistant protective film in the present invention. If the atomic ratio x of B to Zr, the atomic ratio z of Si, and the atomic ratio y of O in this film are x + z ≧ 0.05, the film becomes amorphous and becomes a film having high scratch resistance and abrasion resistance. It is preferred. If x + z ≦ 19, the alkali resistance is also good, so that in the ZrB _x Si _z O _y film, 0.05
It is preferable that ≦ x + z ≦ 19. However, as described above, since B ₂ O ₃ is hygroscopic and absorbs moisture in the air and is dissolved, it is better not to include too much in the ZrB _x Si _z O _y film. Specifically, if the film contains B ₂ O ₃ so that ZrO ₂ <25 mol% and SiO ₂ <25 mol% and the remainder becomes B ₂ O ₃ , the chemical durability becomes insufficient. . That is, ZrB _x Si
_If Zr: B: Si (atomic ratio) in the _z O _y film is 1: x: z, 1 / (1
+ X + z) <0.25 and z / (1 + x + z) <0.25, that is, the composition of x + z−3> 0 and x−3z + 1> 0 has poor chemical durability.

y is considered to be a composite system of ZrO ₂ + B ₂ O ₃ + SiO ₂ for the same reason as described in the case of ZrB _x O _y , and y is 2 + 1.
It is preferable to be about 5x + 2z. Therefore, almost 2 <y <
It is preferably about 40. The higher the content of B and Si, the more
The refractive index of the ZrB _x Si _z O _y film decreases.

Metals other than Zr, i.e., oxides containing Ti, Hf, Sn, Ta, In, and at least one of B and Si also become amorphous, and have sufficient scratch resistance and abrasion resistance. can get. TiSi _z O
_{The y} film is shown as an example in Sample 15 of Table 1.

The scratch-resistant protective film 1 made of an amorphous oxide according to the present invention is made of an element other than Zr, Ti, Hf, Sn, Ta, In, B, Si, O, for example, B,
As in the case of Si, glass constituent elements such as P and As may be contained in trace amounts for the purpose of improving durability, adjusting optical constants, stability during film formation, improving film formation speed, and the like.

The thickness of the scratch-resistant protective film 1 used in the present invention is usually 100 to 5
It is preferably 000 °. This is because if it is too thin, sufficient scratch resistance cannot be obtained, and if it is too thick, peeling of the film is likely to occur and productivity is poor.

In the case of the protective plate used for the barcode reader reading part, considering the transmittance of the laser beam of wavelength 6328Å, the thickness
It is desirable to use 5 mm soda-lime glass and to set the scratch-resistant protective film to a thickness of 300 to 600 Å.

As a method for producing the scratch-resistant protective film 1 in the present invention, a film forming method such as a vapor deposition method, a sputtering method or an ion plating method can be used, and the production method is not particularly limited. However, the sputtering method does not melt the raw material among these, has good control of the film composition and good reproducibility, has a high energy of particles reaching the substrate, and can easily obtain a film having good adhesion. Then, the scratch-resistant protective film 1 made of the amorphous film according to the present invention can be obtained. Also,
An ion implantation method may be used in combination as a means for enhancing the adhesion of the film to the substrate. That is, high-energy argon ions or oxygen ions of about several tens keV are irradiated from above the scratch-resistant protective film 1 formed on the glass substrate, so that a mixed layer is formed between the scratch-resistant protective film and the glass substrate. By forming, the adhesion to the glass substrate can be enhanced. Further, it is also effective to apply a thin organic lubricating film on the abrasion-resistant protective film 1 to further reduce the friction coefficient depending on the application.

FIG. 2 shows a schematic diagram of an example of the barcode reader.
Reference numeral 3 is a protective plate of the bar code reading unit. The product with the barcode attached is slid over this, and the barcode is read.

[Operation] As factors affecting the scratch resistance of the protective film, the lubricity of the film,
The hardness of the film and the adhesion of the film to the substrate are considered. In the present invention, among the above factors, it is considered that the lubricity of the film is particularly improved as compared with the conventional film. In conventional films such as TiO ₂ and SnO ₂ , even if the film is said to be amorphous in X-ray, it is said that it is a set of very fine microcrystals according to microscopic observation with an electron microscope. It is considered. Such reports are, for example, from the Japanese Journal of Appl.
ied Physics, 1979, Vol. 18, p. 1937.
A feature of the present invention is that boron (B) or silicon (Si) is added to the zirconium oxide film. The atomic radius of boron is 0.41%, the atomic radius of silicon is 0.54%, and zirconium and oxygen are each 0.98%. It is thought that boron or silicon enters the lattice spacing of zirconium oxide (ZrO ₂ ), which is smaller than {, 1.26}. This is considered to destroy the lattice of zirconium oxide, hinder the growth of crystal grains of zirconium oxide, and make the film more amorphous.
It is considered that the unevenness of the film surface is less in the method of forming an amorphous film than in a film that is an aggregate of microcrystals, and as a result, the amorphous film in the present invention is considered to have a reduced friction coefficient.
For this reason, it is considered that the amorphous film in the present invention has excellent lubricity and is less likely to be caught, so that it is less likely to be scratched by friction and high scratch resistance performance can be obtained.

[Example] The protective plate of the bar code reading section of the present invention was prepared by a DC sputtering method using a soda-lime glass having a thickness of 5 mm as follows. The target contains 67% of boron (B) (atomic%), zirconium (Zr) and boron (B)
Was used. The introduced gas has a flow rate ratio of oxygen (O ₂ ) of 30.
Using a mixed gas of oxygen (O ₂ ) and argon (Ar), the vacuum degree in the vacuum chamber was set to 3.5 mTorr. A DC power supply was connected to the target, and -600 V was applied to generate a glow discharge. The discharge current density at this time was 20 mA / cm ² . In this state, open the shutter for 37.5 seconds,
To 5mm thick soda-lime glass plate was deposited a ZrB _x O _y amorphous film (referred to as Sample 1).

The thickness of the film formed on the substrate was 500 °, the film was colorless and transparent, and the refractive index was 1.8. When the content of boron in the film was examined by ESCA, the atomic ratio x of boron to zirconium was 2.0.

Separately, the target (silicon) ratio (atomic%)
67% of the zirconium (Zr) and silicon (Si) sintered body was sputtered under the same conditions as above, and a ZrSi _z O _y amorphous film was formed on a soda-lime glass plate with a thickness of 5 mm. Was formed (referred to as Sample 2).

The film thickness was 900 °, the film was colorless and transparent, and the refractive index was 1.7. The atomic ratio Z of Si to Zr in the film was 2.0.

The dynamic friction coefficient of stainless steel balls with a diameter of 6 mm at a load of 50 g and a substrate moving speed of 150 mm / min was calculated using the conventionally used spray-coated TiO ₂ and SnO ₂ , soda-lime glass surface, ZrB _x O _y (Sample 1 ), ZrSi _z O _y (Sample 2) Wipe the surface of the scratch-resistant protective film consisting of an amorphous film with a cloth soaked in acetone, and then measure it using a Heidon 14 type surface texturer manufactured by Shinto Chemical I just did
0.204,0.282,0 for each of the above 5 types of samples.
The values of 145, 0.142 (Sample 1) and 0.138 (Sample 2) were obtained. As described above, the scratch-resistant protective film of the present invention is extremely excellent in lubricity and is less likely to be caught, and thus is considered to be less likely to be scratched by friction. In fact, the load
A test was carried out by applying 500 g and reciprocating a sand eraser with a diameter of 5 mm 10 times with a stroke of 30 mm. According to the visual observation, the scratch-resistant protective film consisting of ZrB _x O _y and ZrSi _z O _y among the above 5 types of samples was observed. Had the fewest defects.

[Effects of the Invention] Protective film 1 in the protective plate of the barcode reading unit of the present invention
Has improved lubricity compared to the conventional protective films such as TiO ₂ and SnO ₂ . Therefore, since the scratch-resistant protective film of the present invention has sufficient scratch resistance, it is possible to provide an excellent protective plate for the reading portion of the barcode reader.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of a protective plate of a bar code reading unit of the present invention. Reference numeral 1 is a scratch-resistant protective film, 2 is a transparent plate, and 3 is a protective plate for a bar code reading section. FIG. 2 is a schematic perspective view of the barcode reader. Reference numeral 3 is a protective plate of the bar code reading unit with a scratch resistant protective film of the present invention attached to the bar code reading unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-122031 (JP, A) JP-A-3-73941 (JP, A) JP-A-2-901 (JP, A) JP-A-4- 265252 (JP, A) JP 61-167546 (JP, A) JP 62-216944 (JP, A)

Claims (5)

(57) [Claims] 1. An oxide containing, as a main component, at least one of Zr, Ti, Hf, Sn, Ta and In and at least one of B (boron) and Si (silicon) on a transparent substrate. And a scratch-resistant protective film made of an amorphous oxide film. 2. An oxide containing, as a main component, at least one of Zr, Ti, Hf, Sn, Ta and In and at least one of B (boron) and Si (silicon) on a transparent substrate. A bar code reader having a protective plate of a bar code reading section on which a scratch-resistant protective film made of an amorphous oxide film is formed. 3. The abrasion-resistant protective film is mainly composed of an oxide (ZrB _x O _y ) containing Zr (zirconium) and B (boron), and the atomic ratio x of boron to zirconium in the film is 0.10 <.
2. The protective plate for a bar code reading section according to claim 1, wherein the amorphous oxide film has x ≦ 3 and an atomic ratio y of oxygen to zirconium is 2 <y ≦ 6.5. Barcode reader listed. 4. The abrasion-resistant protective film is made of Zr (zirconium).
An oxide containing Si (silicon) (ZrSi _z O _y ) as a main component, and an atomic ratio z of silicon to zirconium is 0.05 ≦ z
≦ 19, and the atomic ratio y of oxygen to zirconium is 2.
The bar code reader according to claim 1, or the bar code reader according to claim 2, which is an amorphous oxide film satisfying 1 ≦ y <40. 5. An abrasion-resistant protective film is made of an oxide (ZrB _x Si _z O) containing Zr (zirconium), B (boron) and Si (silicon).
_y ) as the main component, the atomic ratio of boron to zirconium in the film is x, the atomic ratio of silicon to zirconium is z, and the atomic ratio of oxygen to zirconium is y:
0.05 ≦ x + z ≦ 19 (where x + z−3> 0 and x−3z +
The composition of 1> 0 is excluded), and it is an amorphous oxide film with 2 <y <40. The protective plate of the bar code reading section according to claim 1, or the bar according to claim 2. Code reader.