TW201716465A - Imaging lens - Google Patents

Abstract

An imaging lens comprising a polycarbonate that contains formulae (1) and (2) in the proportions indicated below, said imaging lens having a specific refractive index and Abbe number, and having the physical characteristics of a low birefringence and coefficient of water absorption. 50 mol%≤(1)<70 mol%; 30 mol%<(2)≤50 mol%.

Description

Camera lens

The present invention relates to an image pickup lens composed of a specific polycarbonate resin.

In recent years, almost all mobile phones have been equipped with camera functions, and recently there have been mobile phones equipped with a high-resolution camera function comparable to digital still cameras. The pixel size of the imaging element is miniaturized, and the pixel pitch is less than 1.4 μm. On the other hand, in view of the small size or thinness of the mobile phone, the imaging lens also needs to be miniaturized. Therefore, with the high resolution of the imaging element and the miniaturization of the imaging lens, it is urgent to reduce the birefringence of the imaging lens or to improve the aberration correction capability. In the past, an imaging lens for a portable device such as a mobile phone or a smart phone was manufactured by aspherical plastic, and the aberration correction can be combined with a lens shape by a lens having different optical characteristics (refractive index, Abbe number). Come on.

Among the optical transparent resins that have been put to practical use in the lens, polycarbonate resins (nd=1.584) using bisphenol A as a raw material have been widely used as resins having a high refractive index and a low Abbe number. However, polycarbonate resin using bisphenol A as a raw material has a significant disadvantage of birefringence and therefore cannot be Used in high resolution cameras in recent years.

As a method for reducing the birefringence, a polycarbonate copolymer containing a mercapto group or an oxetane undecyl group has been disclosed (Patent Documents 1 and 2). Patent Document 1 discloses an information recording medium such as an optical disc, and Patent Document 2 discloses an optical disc, an optical film, an optical pickup, a reading lens (only 0 or 1 of an optical signal is recognized), but an imaging lens is not assumed, and thus refraction is The characteristics required for the imaging lens such as rate, Abbe number, alignment birefringence, and water absorption rate are unknown. Further, the literature discloses a camera lens composed of a polycarbonate resin and a styrene resin having a specific structure (Patent Document 3). However, since the resin of this patent document contains a polystyrene component and even an incompatible component mixes with each other, there exists a subject that the resin of the resin is brittle and heat resistance is low.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. Hei 9-268225

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-67990

Patent Document 3: Japanese Laid-Open Patent Publication No. 2009-93146

Accordingly, an object of the present invention is to provide an image pickup lens which has a specific refractive index, an Abbe number, and a low birefringence and a low water absorption rate by using a specific polycarbonate resin.

In order to solve the above problems, the inventors of the present invention have repeatedly studied the resin for a new image pickup lens, and as a result, found that 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene and 3,9-double are (1,1-Dimethyl-2-hydroxyethyl)2,4,8,10-tetraoxaspiro[5.5]undecane is copolymerized at a specific composition ratio to obtain a polycarbonate resin for an image pickup lens, The resin can be used as an image pickup lens having a specific refractive index and an Abbe number and having low birefringence and low water absorption.

That is, according to the present invention, an image pickup lens composed of a polycarbonate resin shown below is provided.

An imaging lens comprising a polycarbonate comprising the formulas (1) and (2) in a ratio of the following formula.

50 mol% ≦ (1) < 70 mol%

30 mol% < (2) ≦ 50 mol%

[Chemical 2]

2. The image pickup lens according to the above 1, wherein the polycarbonate resin has a refractive index of 1.57 to 1.60 and an Abbe number of 27 to 31.

3. The image pickup lens according to item 1 or 2 above, wherein the film composed of the polycarbonate resin has an alignment birefringence of 2 × 10 ^-3 or less.

4. The image pickup lens according to any one of the above 1 to 3, wherein the polycarbonate resin has a refractive index of from 1.58 to 1.59.

5. The image pickup lens according to any one of the above 1 to 4, wherein the polycarbonate resin has an Abbe number of 27.5 to 29.5.

6. The image pickup lens according to any one of the above 1 to 5, wherein the polycarbonate resin has a specific viscosity of 0.12 to 0.32.

7. The image pickup lens according to any one of the above 1 to 6, wherein the water absorption of the polycarbonate resin is 0.2% or less.

8. The image pickup lens according to any one of the above 1 to 7, which is used in any of a mobile phone, a smart phone, a tablet computer, a personal computer, a digital camera, a video camera, a driving recorder, and a surveillance camera.

The resin used in the image pickup lens of the present invention is obtained by using 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene and 3,9-bis(1,1-dimethyl-2-). Hydroxyethyl) 2,4,8,10-tetraoxaspiro[5.5]undecane is copolymerized at a specific composition ratio to obtain a polycarbonate resin for an image pickup lens, which can be obtained by using the resin. An imaging lens having a specific refractive index and an Abbe number and having low birefringence and low water absorption rate is particularly effective in an industry that needs to exhibit these characteristics.

Hereinafter, the imaging lens of the present invention will be specifically described in order.

<Polycarbonate resin>

The polycarbonate resin used in the image pickup lens of the present invention has a refractive index of 1.57 to 1.60 at a measurement temperature of 25 ° C and a measurement wavelength of 589 nm, preferably 1.58 to 1.59.

The polycarbonate resin used in the image pickup lens of the present invention preferably has an Abbe number at a measurement temperature of 25 ° C of 27.0 to 31.0, preferably 27.5 to 29.5. The Abbe number is calculated from the measurement temperature: 25 ° C, and the measurement wavelengths: 486 nm, 589 nm, and 656 nm, using the following formula.

ν=(nD-1)/(nF-nC)

nD: refractive index at a wavelength of 589 nm

nC: refractive index at a wavelength of 656 nm

nF: refractive index at a wavelength of 486 nm

The polycarbonate resin used in the image pickup lens of the present invention contains the formulas (1) and (2).

[Chemical 3]

The polycarbonate resin used in the image pickup lens of the present invention contains 50 mol% or more of the formula (1) of less than 70 mol%, more preferably 55 to 65 mol%, more preferably 57 to 64 mol%. Further, the formula (2) is contained more than 30 mol% and 50 mol% or less, preferably 35 to 45 mol%, more preferably 36 to 43 mol%.

The polycarbonate resin used in the image pickup lens of the present invention contains the repeating unit represented by the formula (1) and the formula (2), and can be copolymerized with other diol components to the extent that the characteristics of the present invention are not impaired. The other diol component is preferably 10 mol% or less in all the repeating units. Examples of the other diol component include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, decanediol, and tricyclo [5.2.1.0 ^2,6 ]nonane II. Methanol, cyclohexane-1,4-dimethanol, decalin-2,6-dimethanol, norbornane dimethanol, pentacyclopentadecane dimethanol, cyclopentane-1,3-dimethanol, different Sorbitol, hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 1,1- Bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl) Benzene, bis(4-hydroxyphenyl)fluorene, bis(4-hydroxyphenyl) sulfide, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1 , 1-bis(4-hydroxyphenyl)cyclohexane, biphenol, bisphenol oxime, biscresol oxime, and the like.

The polycarbonate resin used in the image pickup lens of the present invention preferably has a specific viscosity of from 0.12 to 0.32, more preferably from 0.18 to 0.30. When the specific viscosity is 0.12 to 0.32, the balance between formability and strength is excellent.

The absolute value of the alignment birefringence (?n) of the polycarbonate resin used in the image pickup lens of the present invention is preferably in the range of 0 to 6 × 10 ^-3 , preferably 0 to 4 × 10 ^-3 , more preferably 0. ~2×10 ^-3 . The birefringence (Δn) of the alignment was such that the cast film having a thickness of 100 μm obtained from the polycarbonate resin was stretched twice at Tg + 10 ° C and measured at a wavelength of 589 nm.

The polycarbonate resin used in the image pickup lens of the present invention preferably has a total light transmittance of 80% or more, preferably 85% or more, more preferably 88% or more at a thickness of 1 mm.

The polycarbonate resin used in the image pickup lens of the present invention preferably has a water absorption ratio of 0.20% or less after immersion at 23 ° C for 24 hours, and preferably 0.17% or less.

The glass transition point of the polycarbonate resin used in the image pickup lens of the present invention is preferably 120 to 160 ° C, and preferably 125 to 150 ° C.

<Method for Producing Polycarbonate Resin>

The polycarbonate resin used in the image pickup lens of the present invention is passed through Conventional reaction means for producing a polycarbonate resin, for example, a method in which a diol component is reacted with a carbonate precursor such as a carbonic acid diester. Next, the basic means will be briefly explained for these manufacturing methods.

The transesterification reaction using a carbonic acid diester as a carbonate precursor is carried out by heating a predetermined ratio of an aromatic dihydroxy component and a carbonic acid diester under an inert gas atmosphere while stirring, and distilling the produced alcohol or phenol. The method is out. The reaction temperature will vary depending on the boiling point of the alcohol or phenol to be produced, etc., and is usually in the range of 120 to 300 °C. The reaction is carried out under reduced pressure from the initial stage, and the produced alcohol or phenol is distilled off, and the reaction is completed. In addition, terminal stoppers, antioxidants, and the like may be added as necessary.

The carbonic acid diester used in the transesterification reaction may, for example, be an ester of a 6- to 12-valent aromatic group or an aralkyl group which may be substituted. Specific examples thereof include diphenyl carbonate, bis(tolyl) carbonate, bis(chlorophenyl) carbonate, and m-cresol carbonate. In particular, diphenyl carbonate is particularly preferred. The amount of use of diphenyl carbonate is preferably from 0.95 to 1.10 mol, preferably from 0.98 to 1.04 mol, based on 1 mol of the total of the dihydroxy compound. Further, in the melt polymerization method, a polymerization catalyst may be used in order to accelerate the polymerization rate, and examples of the polymerization catalyst include an alkali metal compound, an alkaline earth metal compound, a basic phosphorus compound, a nitrogen-containing compound, and a metal compound. Such a compound is suitably used as an organic acid salt, an inorganic salt, an oxide, a hydroxide, a hydride, an alkoxide, a 4-grade ammonium hydroxide or the like of an alkali metal or an alkaline earth metal, and these compounds may be used singly or in combination.

An alkali metal compound, which can be exemplified by sodium hydroxide or hydroxide Potassium, barium hydroxide, lithium hydroxide, sodium hydrogencarbonate, sodium carbonate, potassium carbonate, barium carbonate, lithium carbonate, sodium acetate, potassium acetate, barium acetate, lithium acetate, sodium stearate, potassium stearate, stearic acid Acid bismuth, lithium stearate, sodium borohydride, sodium benzoate, potassium benzoate, bismuth benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenyl phosphate, double The disodium salt, the dipotassium salt, the diterpene salt, the dilithium salt of the phenol A, the sodium salt, the potassium salt, the phosphonium salt, the lithium salt and the like of the phenol.

The alkaline earth metal compound may, for example, be magnesium hydroxide, calcium hydroxide, barium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, barium carbonate, barium carbonate, calcium hydrogencarbonate, barium hydrogencarbonate, magnesium hydrogencarbonate or barium hydrogencarbonate. , magnesium diacetate, calcium diacetate, barium diacetate, barium diacetate and the like. Examples of the basic boron compound include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, and trisole. Ethylmethylboron, triethylbenzylboron, triethylphenylboron, tributylbenzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenyl A sodium salt, a potassium salt, a lithium salt, a calcium salt, a barium salt, a magnesium salt or a barium salt of boron, butyltriphenylboron or the like.

Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, or a quaternary phosphonium salt.

Examples of the nitrogen-containing compound include an alkyl group and an aromatic group such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide. Class 4 ammonium hydroxides. Further, examples thereof include triethylamine, dimethylbenzylamine, and triphenylamine. An imidazole such as a tertiary amine, 2-methylimidazole, 2-phenylimidazole or benzimidazole. Further, an alkali or a basic salt such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate or tetraphenylammonium tetraphenylborate may be exemplified.

The metal compound may, for example, be a zinc aluminum compound, a ruthenium compound, an organotin compound, a ruthenium compound, a manganese compound, a titanium compound, a zirconium compound or the like. These compounds may be used alone or in combination of two or more.

The amount of the polymerization catalyst to be used may be in the range of 1 × 10 ^-9 to 1 × 10 ^-2 equivalents, preferably 1 × 10 ^-8 to 1 × 10 ^-3 equivalents per 1 mole of the diol component. Preferably, it is 1 × 10 ^-7 ~ 1 × 10 ^-5 equivalent.

Alternatively, a catalyst deactivator may be added later in the reaction as necessary. The catalyst deactivator used can be effectively used as a known catalyst deactivating agent, and among them, an ammonium salt or a phosphonium salt of a sulfonic acid is preferable. Further, it is also preferably a salt of dodecylbenzenesulfonic acid such as tetrabutylphosphonium dodecylbenzenesulfonate or a p-toluenesulfonic acid salt such as tetrabutylammonium p-toluenesulfonate.

In addition, the sulfonate is preferably methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, Butyl p-toluenesulfonate, octyl p-toluenesulfonate, phenyl p-toluenesulfonate and the like. In particular, tetrabutylphosphonium dodecylbenzenesulfonate is most suitable.

When the amount of the catalyst deactivator used is at least one polymerization catalyst selected from the group consisting of an alkali metal compound and/or an alkaline earth metal compound, it is preferred to inactivate 0.5 to 50 moles per 1 mole of the catalyst. The ratio of the agent is preferably 0.5 to 10 moles, more preferably 0.8 to 5 moles.

In addition, the polycarbonate resin of the present invention may be blended with a heat stabilizer, a plasticizer, a light stabilizer, a polymeric metal deactivator, a flame retardant, a lubricant, an antistatic agent, a surfactant, and an antibacterial agent according to the use or as necessary. Additives such as agents, ultraviolet absorbers, and release agents.

In addition, heat stabilizers, plasticizers, light stabilizers, polymeric metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, ultraviolet absorbers, etc. may be blended according to the application or as necessary. An additive such as a release agent.

<Method of Manufacturing Image Pickup Lens>

The image pickup lens of the present invention can be formed and processed by any method such as injection molding, compression molding, injection compression molding, melt extrusion molding, casting, etc., and is particularly suitable for injection molding.

The molding conditions for the injection molding are not particularly limited, and the cylinder temperature of the molding machine is preferably 180 to 320 ° C, preferably 220 to 300 ° C, and more preferably 240 to 280 ° C. Further, the temperature of the metal mold is preferably 70 to 130 ° C, preferably 80 to 125 ° C, and more preferably 90 to 120 ° C. The injection pressure is preferably 50 to 1,700 kgf/cm ² , more preferably 500 to 1,600 kgf/cm ² , and more preferably 1,000 to 1,500 kgf/cm ² .

The image pickup lens of the present invention can be used for an image pickup lens of a smart phone, a digital camera, a video camera or the like.

[Examples]

The invention is further illustrated by the following examples.

Examples 1 to 3 and Comparative Examples 1 to 4

The evaluation was carried out in accordance with the following method.

(1) Specific viscosity: The polycarbonate resin obtained after completion of the polymerization was sufficiently dried, and 0.7 g of the pellet was dissolved in 100 ml of dichloromethane to form a solution, and then the specific viscosity (ηsp) of the solution at 20 ° C was measured. .

(2) Copolymerization ratio: Measurement was carried out by proton NMR of JNM-AL400 manufactured by JEOL Ltd. In the vicinity of 7.6 to 7.8 ppm, the integral ratio of the peak generated by the structure of the formula (1) and the peak of the formula (2) in the vicinity of 0.8 to 1.1 ppm was obtained.

(3) Refractive index (nD) and Abbe number (ν): The thickness of the film obtained by injection molding was 0.3 mm using an Abbe refractometer made of ATAGO DR-M2. The refractive index of a 5 mm circular plate at 25 °C. The Abbe number is calculated from the refractive indices of the measurement wavelengths = 486 nm, 589 nm, and 656 nm using the following formula.

ν=(nD-1)/(nF-nC)

nD: refractive index at a wavelength of 589 nm

nC: refractive index at a wavelength of 656 nm

nF: refractive index at a wavelength of 486 nm

(4) Directional birefringence (?n): After dissolving the polycarbonate resin in methylene chloride, it was cast on a glass dish and sufficiently dried to prepare a cast film having a thickness of 100 μm. The film was stretched twice at a glass transition point (Tg) + 10 ° C, and an ellipsometer M-220 manufactured by JASCO Corporation was used to measure the phase difference (Re) at 589 nm, and the alignment was determined according to the following formula. Birefringence (Δn). In addition, the glass transfer point is made by Shimadzu Corporation. The DSC-60A was measured at a temperature increase rate of 20 ° C / min.

△n=Re/d

△n: alignment birefringence

Re: phase difference

d: thickness

(5) Water absorption ratio: A plate-shaped formed sheet obtained by injection molding was measured in accordance with ISO62.

(6) Evaluation of optical distortion of the lens: At a cylinder temperature of 280 ° C and a mold temperature of 120 ° C, a SE30DU injection molding machine manufactured by Sumitomo Heavy Industries Co., Ltd. was used, which has a thickness of 0.2 mm, a convex curvature radius of 5 mm, and a concave radius of curvature. 4mm, A 5 mm aspheric lens was injection molded. The aspherical lens was sandwiched between two polarizing plates, and the optical distortion was evaluated by visually observing the light leakage according to the orthogonal polarization method. The evaluation is based on the following criteria.

◎: There is almost no light leakage.

○: Light leakage was slightly observed.

×: Significant light leakage.

(7) Evaluation of Formability of Lens: By the same method as (6), the filling failure of the formed aspherical lens, the molding failure, the brittleness of the lens, the presence or absence of the deposit of the metal mold, and the like were visually observed. The evaluation is based on the case where 500 pieces are formed, and the probability of producing defective products is less than 1% (◎), less than 1 to 5% (○), less than 5 to 10% (Δ), and 10% or more (×).

[Example 1]

1,9-bis(4-(2-hydroxyethoxy)phenyl)indole (hereinafter abbreviated as BPEF) 110.50 parts, 3,9-bis(1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro[5.5]undecane (hereinafter abbreviated as SPG) 45.05 parts, 87.40 parts of diphenyl carbonate, and sodium hydroxide 8.00×10 ^-5 parts as a catalyst, four Methylammonium hydroxide (3.65 × 10 ^-3 parts) was placed in a reaction vessel equipped with a stirrer and a distillation apparatus, and nitrogen substitution was performed three times, and then the jacket was heated to 180 ° C to melt the raw material. After complete melting, the pressure was reduced to 20 kPa in 20 minutes while the jacket was heated to 260 ° C at a rate of 60 ° C/hr to carry out a transesterification reaction. Then, the sleeve was kept at 260 ° C, the pressure was reduced to 0.13 kPa in 80 minutes, and the polymerization reaction was carried out for 30 minutes under conditions of 260 ° C and 0.13 kPa or less. After the completion of the reaction, the produced polycarbonate resin was granulated and taken out at the same time to obtain polycarbonate resin pellets. The specific viscosity, the copolymerization ratio, and the complex birefringence were measured using the pellets, and the results are shown in Table 1. Further, the pellet was dried at 110 ° C for 4 hours, and then formed into a test piece by injection molding, refractive index (nD), Abbe number (ν), water absorption, optical distortion evaluation of the lens, and lens formability. The results of the measurement are shown in Table 1.

[Embodiment 2]

Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that the BPEF was changed to 105.24 parts and the SPG was changed to 48.70 parts. The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1.

[Example 3]

Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that the BPEF was 98.22 parts and the SPG was 53.57 parts. The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1.

[Example 4]

Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that the BPEF was 87.70 parts and the SPG was 60.88 parts. The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1.

[Comparative Example 1]

According to the method described in Example 17 of Japanese Patent No. 3160209, polycarbonate resin pellets were obtained. The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1. When the lens formability was evaluated, many lenses were broken or the gate was broken, and the formability was poor.

[Comparative Example 2]

Polycarbonate resin pellets were obtained in the same manner as in Example 1 except that the BPEF was 52.62 parts and the SPG was 85.23 parts. The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1.

[Comparative Example 3]

The polycarbonate resin AD-5503 manufactured by Teijin Co., Ltd. was used for measurement in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 4]

According to the method described in Example 3 of Japanese Patent No. 5,217,644, polycarbonate resin pellets were obtained. In other words, 50.0 parts of the above-mentioned IUPILON H-4000 (manufactured by Mitsubishi Engineering Plastics Co., Ltd.) as a polycarbonate resin and 50.0 parts of the above-mentioned DYLARK D-232 (manufactured by NOVA Chemicals Co., Ltd.) as a styrene resin were extruded. The machine was kneaded and granulated at 255 ° C to obtain pellets of a resin composition for a light lens.

The pellets were measured in the same manner as in Example 1 using the pellets, and the results are shown in Table 1.

Industrial availability

The image pickup lens of the present invention has a specific refractive index, an Abbe number, and has low birefringence and low water absorption, so it is used in mobile phones, smart phones, tablets, personal computers, digital cameras, cameras, driving recorders, and surveillance. An imaging lens such as a camera is extremely effective.

Claims (8)

An image pickup lens comprising polycarbonate of the formula (1) and the formula (2) in a ratio of the following formula, 50 mol% ≦(1)<70 mol% 30 mol%<(2)≦50 mol% The imaging lens of claim 1, wherein the polycarbonate resin has a refractive index of 1.57 to 1.60 and an Abbe number of 27 to 31. The image pickup lens according to claim 1 or 2, wherein the film composed of the polycarbonate resin has an alignment birefringence of 2 × 10 ^-3 or less. The imaging lens according to any one of claims 1 to 3, wherein the refractive index of the polycarbonate resin is from 1.58 to 1.59. The imaging lens according to any one of claims 1 to 4, wherein the polycarbonate resin has an Abbe number of 27.5 to 29.5. An image pickup lens according to any one of claims 1 to 5, The specific viscosity of the polycarbonate resin is from 0.12 to 0.32. The image pickup lens according to any one of claims 1 to 6, wherein the water absorption of the polycarbonate resin is 0.2% or less. The image pickup lens according to any one of claims 1 to 7 is used for any of a mobile phone, a smart phone, a tablet computer, a personal computer, a digital camera, a video camera, a driving recorder, and a surveillance camera.