JP2001034702A - Information record symbol reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To visually confirm the position of an information record symbol from a direction just above. SOLUTION: This information record symbol reader 7 which has an image sensor 21 optically reading an information record symbol 4 of a prescribed area printed on a printed matter, etc., from a data reading opening 15 and a decoding means converting the symbol 4 into corresponding prescribed data on the basis of image data read by the sensor 21, is provided with a transparent prism 14 in the opening 15, and the sensor 21 is also arranged on an optical path where a part of the image light of the symbol 4 made incident on the prism 14 is reflected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optically capturing an information recording symbol such as a two-dimensional bar code such as a bar code, particularly a data code, into an image sensor and converting the information recording symbol into a predetermined electric signal corresponding to the information recording symbol. The present invention relates to an information recording symbol reading device that reads data recorded in an information recording symbol after conversion.

[0002]

2. Description of the Related Art Barcodes have been mainly used as information recording symbols on which product information such as product numbers and price data are recorded, but recently, more product information can be recorded. Etc. are being adopted.

As such an information recording symbol reading device, a handy terminal or the like having an image pickup device such as a CCD, which is an image sensor, is usually used, and an information recording symbol reading port formed in these handy terminals is used. The information recording symbol is taken in through an optical system such as a lens and converted into an image signal by the CCD, and based on the image signal, a predetermined electric signal corresponding to each data recorded in the read information recording symbol. The signal is reproduced, and the product data or the like is stored or output to the outside.

[0004] Unless the entire information recording symbol such as a two-dimensional bar code is read from the reading port, it is not converted into predetermined data and a reading error occurs. It is necessary to arrange a handy terminal or the like so that the entire information recording symbol falls within a predetermined range, and if the alignment between the handy terminal and the information recording symbol is not properly performed, the reading must be repeatedly performed many times. There were times when I had to.

[0005] Therefore, as a method of solving these alignment problems, a mirror shutter or the like is provided in a path of light incident on the CCD, which is the image sensor, and the alignment is performed like a camera. There has been proposed a method in which a mirror shutter is closed to guide incident light to a CCD for reading, and a method in which image data converted by the CCD is displayed on a display device or the like to perform alignment.

[0006] However, although the above-mentioned methods can surely perform the positioning, when the mirror shutter or the like is provided, the optical system becomes complicated due to the mechanical operation, and the size of the obtained handy terminal is increased. In addition, there is a problem that the cost is high, and the method of performing the alignment by displaying the image on the display device or the like increases the cost because a high-resolution display device is provided, and consumes less power. There were problems such as an increase.

For this reason, the present inventors have previously disclosed in Japanese Patent Laid-Open No.
As described in Japanese Patent No. 7566, in order to facilitate the alignment between the handy terminal and the information recording symbol with a simple structure, the reading port is formed of a transparent member such as glass. There has been proposed a reading device that performs reading while visually confirming information recording symbols.

[0008]

As described above, it is necessary to form these reading openings from a member such as glass having transparency so that the position of the information recording symbol to be read from the outside can be confirmed. Although the alignment can be performed with a simple structure, the position of the information recording symbol to be read is determined by the transparent glass or the like because the CCD or the mirror needs to be arranged vertically above the information recording symbol to be read. When the CCD or the like is arranged above the information recording symbol to be read in the vertical direction, as described above, it is difficult to confirm the position only from an oblique direction through the member and the alignment may be difficult. When the focal length of the lens needs to be set in the vertical direction, the handy terminal becomes bulky and inappropriate for the external shape of the product There, furthermore there is a problem that the stability of the handy terminal is lowered at the time of registration.

The present invention has been made in view of such a problem. The position of an information recording symbol to be read can be visually confirmed in a direction directly above the information recording symbol, and the position can be accurately adjusted. It is an object of the present invention to provide an information recording symbol reader that can be implemented with good operability.

[0010]

In order to solve the above-mentioned problem, an information recording symbol reading apparatus according to the present invention is an image recording apparatus for optically reading an information recording symbol of a fixed area printed on a printed material or the like from a data reading port. An information recording symbol reading device, comprising: a sensor; and decoding means for converting the information recording symbol into corresponding predetermined data based on image data read by the image sensor. And the image sensor is disposed on an optical path where a part of the image light of the information recording symbol incident on the transparent prism is reflected. According to this feature, a transparent prism is disposed in the data reading port, and a transparent prism is disposed in the data reading port, for example, such that the oblique side faces upward.
At the time of reading the information recording symbol, the operator can visually confirm that the information recording symbol is located directly below the lower surface of the transparent prism from the direction immediately above the information recording symbol through the hypotenuse surface. Since the image light of the information recording symbol incident from the lower surface of the transparent prism is totally reflected by the oblique surface and enters the image sensor, the positioning at the time of reading is performed with high accuracy and operability. In addition to the above, since the course of the image light of the information recording symbol incident from the lower surface of the transparent prism on the hypotenuse surface of the transparent prism is changed in the horizontal direction,
The height of the handy terminal can be reduced, and the stability at the time of movement in positioning can be improved.

An information recording symbol reading device according to the present invention comprises:
It is preferable that the transparent prism has a substantially right-angled isosceles triangle shape in a sectional view, and the transparent prism is arranged such that its oblique side is at 45 degrees with respect to the printed matter. With this configuration, light in the direction perpendicular to the lower surface, which is the highest intensity image light incident from the lower surface of the transparent prism,
Since the light is totally reflected by the oblique surface of the transparent prism and enters the image sensor, the reading sensitivity of the information recording symbol can be maximized.

An information recording symbol reading device according to the present invention comprises:
It is preferable that the apparatus further comprises an irradiating means for illuminating the information recording symbol. With this configuration, the information recording symbols are illuminated by the irradiating means, so that the visibility of the information recording symbols through the transparent prism can be improved.

[0013] The information recording symbol reading device of the present invention comprises:
Preferably, the irradiating means is formed by a light source provided around an optical path in which the image sensor is arranged. With this configuration, the irradiation light from the light source enters the transparent prism, is reflected and illuminates from the lower surface, and illuminates the entire reading area, so that highly efficient illumination can be performed.

The information recording symbol reading device of the present invention comprises:
Preferably, a plurality of the light sources are provided. With this configuration, the irradiation light from the plurality of light sources is incident on and reflected from the transparent prism from multiple directions, and illuminates the reading area more uniformly from the lower surface, so that illumination with less unevenness can be performed. .

An information recording symbol reading device according to the present invention comprises:
The transparent prism hardly transmits light of a predetermined wavelength of external light incident on the prism, and is capable of transmitting other visible light, and the transparent prism transmits the optical path to the image sensor. It is preferable to provide a filter that allows transmission of light of wavelengths not to be transmitted preferentially and that transmits light of other wavelengths substantially. With this configuration, light having a wavelength read by the image sensor that can be disturbance light does not pass through the filter, and is prevented from entering the data reading port from the outside, and a stable irradiation is performed by the irradiation unit. Since only light having a predetermined wavelength out of the light is incident on the image sensor, it is possible to prevent a reading error or the like caused by disturbance light.

The information recording symbol reading device of the present invention comprises:
It is preferable that an objective lens in an optical path to the image sensor doubles as the filter. With this configuration, it is not necessary to independently provide the filter, the optical system can be simplified, the size of the device can be reduced, and the cost can be reduced.

The information recording symbol reading device of the present invention comprises:
The light irradiated on the information recording symbol from the irradiating means,
It is preferable that the light has a wavelength substantially equal to the wavelength light that is not transmitted through the transparent prism. With this configuration, since the light incident on the image sensor can be efficiently supplied from the irradiation unit, the intensity of the light reflected from the information recording symbol can be increased, and the reading sensitivity can be improved.

An information recording symbol reading device according to the present invention comprises:
The irradiating means emits red light having a predetermined wavelength;
Preferably D

In this way, the red LED has a high luminous efficiency and requires less power to obtain a desired luminance, so that the power consumption by the irradiation device can be reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment) FIG. 1 shows an article ordering sheet 1 for catalog sales used in an embodiment of the present invention. A plurality of rectangular frames divided into a certain size have an area 2 for displaying goods. And an area 3 for displaying a product name, a price, and the like, and an area 5 for displaying a two-dimensional data symbol (data code) 4 as an information recording symbol.

A two-dimensional data symbol (hereinafter abbreviated as a data symbol) 4 has a square shape, and merchandise information data such as a merchandise code, a merchandise name, an inner capacity, a price, etc., corresponding to the data symbol 4 is previously converted and recorded. ing.

As shown in FIG. 1, the data symbol 4 printed on each of the areas 5 is read by disposing a handy terminal 7 as a reading device at a predetermined position on the upper surface thereof.

As shown in FIG. 2, the handy terminal 7 serving as an information symbol reading device has a horizontally long appearance with one end inclined upward, and a function key is provided on the upper surface of the handy terminal 7. An input unit 10 including a numeric keypad and the like for inputting the number of products and the number of products is provided, and a liquid crystal display unit 13 capable of appropriately displaying input information and read information is formed. An illuminating button 11 for illuminating the data symbol 4 when aligning the data symbol 4 and a read button 12 for reading operation are provided on the side surface.

The handy terminal 7 is composed of a lower housing 8 and an upper housing 9, and the lower surface of the end of the handy terminal 7 has a slightly larger read than the data symbol 4 for reading the data symbol 4. An opening 15 is formed, and a substantially triangular prism-shaped transparent prism 14 is arranged in the reading opening 15 as shown in FIG. 3, and the oblique side surface 14 a of the transparent prism 14 is provided in the upper housing 9. It is sandwiched between the lower housing 8 and the upper housing 9 so as to be exposed to the outside through the window 6.

The transparent prism 14 used in this embodiment
As shown in FIG. 4, the side surface 14c and the lower surface 14c
b is a right angle, and the angle between the hypotenuse surface 14a, the side surface 14c, and the lower surface 14b is 45 degrees, which is a right angle 2
In this embodiment, it is an isosceles triangle, and in this embodiment, it is a substantially right-angled isosceles triangle in which a vertex formed by the hypotenuse surface 14a and the lower surface 14b is cut out from the viewpoint of mounting and the like, and the hypotenuse surface 14a is used for ordering. The lower surface 14b is disposed so as to be parallel to the lower surface of the handy terminal 7 that contacts the ordering sheet 1 so that the angle is 45 degrees with respect to the sheet 1.

As described above, by arranging the shape of the transparent prism 14 as a substantially right-angled isosceles triangle so that the oblique surface 14a is at 45 degrees with respect to the order sheet 1, the lower surface 14b The image light of the data symbol 4 having the highest intensity incident at right angles to the data symbol 4 is totally reflected by the oblique surface 14a and is incident on the image sensor 21 provided inside the handy terminal 7. However, the present invention is not limited to this, and the shape and arrangement method of the transparent prism 14 may be appropriately determined depending on the design of the optical system, the shape of the housing, and the like. Changes are optional. Further, it is optional to cut off the apex of the transparent prism 14 for the purpose of attachment or the like as in the present embodiment.

As shown in FIG. 5, the hypotenuse surface 14a of the transparent prism 14 of the present embodiment reflects red light and infrared light having a wavelength of about 660 nm or more, and has a wavelength of less than about 660 nm. A red cut filter 23 that allows visible light to pass therethrough is provided.
Red light having a wavelength of about 660 nanometers or more is reflected from external light incident from the hypotenuse surface 14a exposed to the inclined portion, and only visible light having a wavelength of less than about 660 nanometers enters the transparent prism 14. Has become.

The above-mentioned red cut filter 23 may be any filter that blocks red light and efficiently transmits visible light other than red light. A color filter or the like is exemplified, and if there is no problem in practical use, a green color filter or a blue color filter that also blocks light of a color other than red or red can be used.

The present invention also relates to the red cut filter 2 described above.
The color filter is not limited to 3, and may be formed by thinly applying a paint or the like containing a dye or the like that preferentially reflects the red light of 660 nm, for example. May be used that selectively passes or reflects light having a wavelength of.

The main structure inside the handy terminal 7 will be described with reference to FIG. 3. An optical path 16 is formed inside the handy terminal 7 so as to be connected to the side surface 14c of the transparent prism 14 in the lateral direction. At the position around the optical path, the data symbol 4 has an emission center wavelength of 66.
Red LE that emits a predetermined red light of 0 nm
An illuminating device 18 is provided as an illuminating means made of D. The red light reflected by the data symbol 4 and diverted by the transparent prism 14 is guided to an image sensor 21 in the optical path 16 to form an image. Lens 20
And an image sensor 21 for converting an image of the data symbol 4 into a predetermined electric signal sequence. In the present embodiment, an optical path from the irradiation device 18 is provided at the front of the optical path of the lens 20. A red transmission filter 19 that transmits red light having a center wavelength of 660 nanometers and light having a wavelength in the vicinity thereof preferentially and hardly transmits light of other wavelengths is provided.

Although the red transmission filter 19 is used alone in the present embodiment, the present invention is not limited to this. The red transmission filter 19 is directly attached to the image sensor 21. By using the function of the red transmission filter 19 or adding the function of the red transmission filter 19 to the lens 20, the number of components in the optical path may be reduced to reduce the cost.

In the present embodiment, the illuminating device 18 as the illuminating means is formed by a red LED as described above. This is because the red LED has high luminous efficiency and the required light quantity In the case of the handy terminal 7 driven by the built-in battery 22 and made portable as in the present embodiment, the power consumption of the battery 22 can be reduced. However, the present invention is not limited to this, and the red LED may be an LED of another emission color, or another light source, for example, a cold cathode tube or the like. An EL light emitting element or the like may be used.

As shown in FIG. 6C of the present embodiment, illuminating the data symbol 4 by using the illuminating device 18 including the transparent prism 14 and the red LED is as shown in FIG. As shown in FIG. 6A, when a single LED is used, a region that is not illuminated is generated. Therefore, as shown in FIG. 6B, a plurality of LEDs are used. While the power is large and an area that is unnecessarily illuminated occurs, and because there is always an area that is illuminated redundantly, irradiation unevenness occurs,
Since the light emitted from the red LED is complicatedly refracted and reflected inside the transparent prism 14, the entire reading area is efficiently illuminated from the lower surface of the transparent prism 14, and the illumination intensity is further increased. Even if a plurality of the LEDs are provided, it is preferable because illumination unevenness does not occur, but the present invention is not limited to this.

In this embodiment, the transparent prism 1
4 is made of glass, and both end surfaces 14d (FIG. 6)
(C) is made of a frosted glass having low transparency to prevent light from leaking out of the transparent prism 14 from the both end faces 14d. However, in order to prevent such light leakage, the two end faces are used. 14d may be a mirror surface by aluminum evaporation.

The red light illuminated by the illuminating device 18 is reflected by the data symbol 4 as described above, passes through the reading port 15 which is the reflected light of the data symbol 4, and passes under the transparent prism 14. As shown in FIG. 3, the image light that is incident perpendicular to the direction is redirected by the hypotenuse surface 14 a of the transparent prism 14 and the red transmission filter 1 is turned on.
9, passes through the red transmission filter 19, forms an image on the image sensor 21 by the lens 20, and is converted into predetermined image data by the image sensor 21.

Of the red light illuminated by the illuminating device 18, of the image light not vertically incident on the lower surface of the transparent prism 14, the visible light having a wavelength of less than about 660 nm and the hypotenuse The visible light having a wavelength of less than about 660 nanometers incident on the surface 14a and reflected by the data symbol 4 exits from the hypotenuse surface 14a to the outside as shown in FIG. 4 and FIG. The position of the data symbol 4 can be visually confirmed above the surface 14a.

At this time, as shown in FIG.
4a, red light having a wavelength of about 660 nm or more is reflected by the red cut filter 23 to form only visible light having a wavelength of less than about 660 nm. Since the visible light having a wavelength of less than about 660 nanometers cannot pass through the red transmission filter 19, the light transmitted through the red transmission filter 19 and imaged on the image sensor 21 by the lens 20 passes through the illumination light. Only the red light illuminated by the device 18 is used.
1 is prevented from being adversely affected.

The image data converted by the image sensor 21 is output to a decoding unit (not shown) mounted on the internal substrate 17 for reproducing data recorded in the data symbol 4 based on the image data. The reproduced data such as product information is stored in a storage means (not shown) such as a memory mounted on the internal substrate 17 of the handy terminal 7, and can be displayed on the liquid crystal display unit 13 or continuously to an external computer or the like. In FIG. 3, reference numeral 24 denotes an LCD mounted on an internal substrate 17 for displaying the liquid crystal display unit 13.
Module.

The operation of the handy terminal 7 of the present embodiment will be described below. First, as shown in FIG. 2, the handy terminal 7 is placed on the product ordering sheet 1 and the desired data symbol 4 is entirely placed in the window. It is moved to the approximate center in the section 6 to perform positioning.

At this time, when the light from the outside is small and the data symbols 4 are difficult to see, the illuminating button 11 is operated to irradiate the red light of the predetermined wavelength from the irradiating device 18 so that the data symbols 4 are not illuminated. Of the image light, visible light having a wavelength of less than about 660 nanometers is transmitted through the oblique side surface 14a of the transparent prism 14 to be easily viewed.

When the alignment is completed and the data symbol 4 is to be read, the reading button 12 is pressed to irradiate the irradiation device 18 with red light of the predetermined wavelength. The reflected red light and light incident from the outside enter the red transmission filter 19.

The incident light is first separated by the red transmission filter 19 into red light having a central wavelength of 660 nm in the light and light having a wavelength in the vicinity thereof, and other light. Only light having a wavelength in the vicinity is preferentially transmitted, enters the lens 20, and forms an image on the image sensor 21.

As described above, the image of the data symbol 4 formed on the image sensor 21 is converted into image data, and the predetermined data recorded on the data symbol 4 is reproduced by the decoding unit. Is done.

As described above, by using the transparent prism 14 as in the present embodiment, as shown in FIG. 4, the data symbol 4 can be confirmed from directly above the window 6 and the alignment can be easily performed. Not only can you read
Since the optical path can be in the horizontal direction, the handy terminal 7 can be made horizontal to improve the stability during movement. Further, by providing the red cut filter 23 on the transparent prism 14, the red transmission filter 19 is provided.
Since red light that can pass through the filter does not enter from the outside, almost all of the red light that passes through the red transmission filter 19 is
Since the light is emitted by the irradiating device 18, when the data symbol 4 is read by the image sensor 21, it is possible to prevent the reading from being adversely affected by disturbance light from the outside.

Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to these embodiments, and even if there are changes and additions without departing from the gist of the present invention. include.

For example, in the above embodiment, the red cut filter 23 is connected to the hypotenuse surface 14 a of the transparent prism 14.
However, the present invention is not limited to this, and the red cut filter 23 may be formed in the window 6 of the upper housing 9, and may correspond to the hypotenuse surface 14 a of the transparent prism 14. The present invention also includes providing the red cut filter 23 at the position where the red cut filter 23 is located.

In the above embodiment, the irradiation device 18 emits red light of 660 nanometers, and the transparent member is a red cut filter so as to correspond to this. However, the present invention is not limited to this. Instead, the wavelengths of these lights may be appropriately selected. For example, the irradiation device emits green light of 550 nanometers, and the transparent member serves as a green cut filter, or emits near-infrared light from the irradiation device. The transparent member that emits light may be used as an infrared cut filter.

[0049]

The present invention has the following effects.

(A) According to the first aspect of the present invention, a transparent prism is disposed in the data reading port, and a transparent prism is disposed in the data reading port, for example, such that its oblique side faces upward. Thereby, at the time of reading the information recording symbol, the operator can visually confirm that the information recording symbol is located immediately below the lower surface of the transparent prism from above the information recording symbol through the oblique surface. At the same time, the image light of the information recording symbol incident from the lower surface of the transparent prism is totally reflected by the hypotenuse surface and is incident on the image sensor. Not only can it be carried out with good performance, but it is incident from the lower surface of the transparent prism on the oblique side of the transparent prism. Since the path of image light distribution recording symbol is to be changed in the horizontal direction, the handy terminal becomes possible to reduce the height, it can be enhanced stability during movement in alignment.

(B) According to the second aspect of the present invention, the light having the highest intensity, which is incident on the lower surface of the transparent prism and is perpendicular to the lower surface, is incident on the hypotenuse surface of the transparent prism. Then, the light is totally reflected and enters the image sensor, so that the reading sensitivity of the information recording symbol can be maximized.

(C) According to the third aspect of the invention, the information recording symbols are illuminated by the irradiating means, so that the visibility of the information recording symbols through the transparent prism can be improved.

(D) According to the fourth aspect of the present invention, the irradiation light from the light source enters the transparent prism, is reflected and illuminates from the lower surface, and illuminates the entire reading area. , And highly efficient illumination can be implemented.

(E) According to the fifth aspect of the invention, the irradiation light from the plurality of light sources is incident on and reflected from the transparent prism from multiple directions, so that the reading area is evenly illuminated from the lower surface. Therefore, illumination with less unevenness can be performed.

(F) According to the invention described in claim 6, light of a wavelength which can be disturbing light and read by the image sensor is not transmitted through the filter and is prevented from entering the data reading port from outside. Since only light having a predetermined wavelength out of the stable light emitted from the irradiating means is incident on the image sensor, it is possible to prevent a reading error or the like caused by disturbance light.

(G) According to the seventh aspect of the invention, it is not necessary to provide the filter independently, the optical system can be simplified, the device can be downsized, and the cost can be reduced.

(H) According to the invention of claim 8, since the light incident on the image sensor can be efficiently supplied from the irradiating means, the intensity of the reflected light reflected from the information recording symbol can be increased, and the reading can be performed. Sensitivity can be improved.

(I) According to the ninth aspect of the present invention, the red LED has a high luminous efficiency and requires less power to obtain a desired luminance. It can be kept low.

[Brief description of the drawings]

FIG. 1 is a top view showing the positioning of a product ordering sheet and a handy terminal used in an embodiment of the present invention.

FIG. 2 is an external perspective view showing a handy terminal according to the embodiment of the present invention.

FIG. 3 is a sectional view A of the handy terminal according to the embodiment of the present invention.
It is sectional drawing in -A.

FIG. 4 is an enlarged sectional view showing a transparent prism used in an embodiment of the present invention and an optical path inside the transparent prism.

FIG. 5 is an enlarged sectional view showing a transparent prism used in an embodiment of the present invention and an optical path inside the transparent prism.

FIG. 6A is a diagram illustrating an illumination state when a single LED is used. (B) is a figure which shows the illumination situation at the time of using several LED. (C) is a figure which shows the illumination situation at the time of using several LED of this Example and a transparent prism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Order sheet (printed matter) 2, 3, 5 Area 4 Two-dimensional data symbol (information recording symbol) 6 Window 7 Handy terminal (information recording symbol reader) 8 Lower housing 9 Upper housing 10 Input unit 11 Illumination Button 12 Read button 13 Liquid crystal display unit 14 Transparent prism 14a Oblique surface 14b Lower surface 14c Side surface 14d End surface 15 Reading port 16 Optical path 17 Substrate 18 Irradiation device 19 Red transmission filter (filter) 20 Lens 21 Image sensor 22 Battery 23 Red cut Filter 24 LCD module

Claims (9)

[Claims] An image sensor for optically reading an information recording symbol of a fixed area printed on a printed matter or the like from a data reading port, and a predetermined information recording symbol corresponding to the information recording symbol based on image data read by the image sensor. An information recording symbol reader having a decoding means for converting the information recording symbol into data, wherein a transparent prism is provided in the data reading port, and a part of the image light of the information recording symbol incident on the transparent prism is reflected. An information recording symbol reading device, wherein the image sensor is arranged on an optical path. 2. The transparent prism according to claim 1, wherein a cross-sectional shape of the transparent prism is a substantially right-angled isosceles triangle, and the transparent prism is arranged such that an oblique side thereof is at 45 degrees with respect to the printed matter. Information recording symbol reader. 3. The information recording symbol reading device according to claim 1, further comprising an irradiating means for illuminating the information recording symbol. 4. The information recording symbol reading device according to claim 3, wherein said irradiating means is formed by a light source provided around an optical path in which said image sensor is arranged. 5. The information recording symbol reader according to claim 4, wherein a plurality of the light sources are provided. 6. The transparent prism is configured to hardly transmit light having a predetermined wavelength of external light incident on the prism, and to transmit other visible light, and includes an optical path to the image sensor. The information recording symbol reading device according to claim 3, further comprising a filter that allows light having a wavelength not transmitted by the transparent prism to be transmitted preferentially, and that transmits light of other wavelengths substantially. 7. The information recording symbol reading device according to claim 6, wherein an objective lens in an optical path to the image sensor also serves as the filter. 8. The information recording apparatus according to claim 6, wherein the light irradiated onto the information recording symbol by the irradiation means is light having a wavelength substantially equal to the wavelength light that is not transmitted by the transparent prism. Symbol reader. 9. The information recording symbol reading device according to claim 3, wherein said irradiating means is a red LED that emits red light of a predetermined wavelength.