JPH02138681A - Optical reading device - Google Patents

Abstract

PURPOSE:To effectively use the light radiated from an LED serving as a light source by setting an optical member between the LED and a reading subject to perform the condensing control of the light radiated from the LED into a desired radiating state against two directions. CONSTITUTION:Two LED 5 and 6 are prepared and the light sources. While two types of lenses, i.e., the 1st lenses 7 and 8 and the 2nd lenses 9 and 10 are set at the front of the LED 5 and 6 to control the illumination states of the light radiated from both LED 5 and 6. In such a constitution, the illumination light which is condensed into a band form having the prescribed width in the same direction as the train forming direction of line sensors can be supplied to a reading subject 11. Thus it is possible to effectively use the light radiated from the LED as the illumination light of the subject 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical reading device for optically reading objects to be read, such as bar codes, and more particularly to an optical reading device characterized by illumination means for illuminating the object to be read. It is related to.

2. Description of the Related Art As optical reading devices, CCD barcode leagues, image scanners, and the like are well known.

In addition, the illumination means for illuminating the object to be read such as a bar code in these systems usually uses a light emitting diode (hereinafter simply referred to as LED) that generates high-intensity red light as a light source.
For example, as shown in FIG. 8(a) and (bl), a large number of individual LEDs 11 to 14 are arranged in a row and combined with a diffuser plate 2 (Japanese Patent Publication No. 17270/1983). And even more LED chips 3.~3ffl:
LE with rod lens, which has a rod lens 4 integrated into the
A configuration using a D array 5 is well known.

On the other hand, in order to prevent erroneous reading operations, the illumination means of an optical reading device must be sufficiently bright so as not to be affected by ambient light, and that its illuminance distribution is even. It is also well known that characteristics without . It is also well known that it is preferable that the illumination light be brighter in the peripheral area than in the central area.

The former method secures brightness by employing a large number of LEDs, and also prevents uneven illumination caused by arranging the single LEDs 1□ to 14 in a row. It is suppressed by spreading the It should be noted that the large number of LEDs are provided with a difference in the amount of current supplied between the center and the periphery, making the periphery brighter.

The latter means has a larger number of LEs than the former means.
It is equipped with D chips 3I to 3.1 and a rod lens 4, and the former means provides illumination light that is advantageous in terms of brightness and illumination unevenness. By controlling the current supplied to each chip, or by arranging the chips sparsely in the center and densely in the periphery, brighter illumination light is obtained in the periphery than in the center.

Problems to be Solved by the Invention The above-mentioned conventional examples can all provide illumination light that satisfies the characteristics required as an illumination means for an optical reading device, but when looked at in more detail, it still has the following problems. It has the following disadvantages.

Since the former means suppresses illumination unevenness by using the diffuser plate 2, the amount of light decreases, and the efficiency of using the light emitted from each LED deteriorates.

In other words, when considering the amount of light required to illuminate the object to be read, it means that more LEDs are used than necessary, and as a result, the work of installing LEDs in predetermined positions requires a large number of LEDs.
This has the disadvantage that the work has to be done while adjusting the mounting state of each ED, which is complicated, troublesome, and increases costs.

The latter means has a larger number of LED chips than the former means, and therefore has a smoother illuminance distribution, but this is based on the premise that the brightness of each of the large number of LED chips is controlled to a predetermined state. Needless to say, therefore,
This requires a brightness correction circuit for each of the LED chips, which is disadvantageous in that it becomes expensive in addition to the large number of chips.

The present invention has been made in consideration of the above-mentioned disadvantages, and it is an object of the present invention to provide an optical reading device equipped with an inexpensive illumination means that uses LEDs efficiently.

Means for Solving the Problems An optical reading device according to the present invention includes a light source that is an LED that illuminates an object to be read, such as a bar code, and a line sensor that receives reflected light from the object to be read.

A reading unit that optically reads the object to be read is placed between a light source and the object to be read, and controls to focus the light emitted from the light source in two directions: the same direction and the direction perpendicular to the line sensor row forming direction. However, it is configured to include an optical member that illuminates the reading target in a strip shape having a predetermined width.

Function: Since the optical reading device according to the present invention is configured as described above, the light emitted from the LED, which is the light source, can be focused in a desired state by the optical member, and can be used to illuminate the object to be read very efficiently. It will be possible.

Embodiments Hereinafter, embodiments of the optical reading device of the present invention will be described.

[Embodiment 1] FIG. 1 is a plan configuration diagram showing the basic structure of a first embodiment of the present invention.

This embodiment uses two LEDs 5 and 6 as light sources, and
Two types of lenses are arranged in front of the D5.6 and control the irradiation state of the light emitted from the LED5.6, namely
lens 7.8 and second lens 9. ], O as the basic structure.

11 is an object to be read, for example, a label on which a barcode is formed; 12 is a reading unit, and the column forming direction is the same as the above two LEs.
It includes a line sensor 12a that is provided parallel to the arrangement direction of the D5.6 and receives light from the reading target 11.

Although this embodiment has the basic structure as described above,
The principle of optically reading the reading object 11 by illuminating the reading object 11 by lighting the LED 5.6 and receiving the reflected light in the reading section 12 is the same as that of the conventional example described above. Not even. However, a first lens 7.8 and a second lens 9, 10 are provided between the LEDs 5, 6 and the object to be read, and this point will be explained below.

FIG. 2 (al is a plan configuration diagram in which only the LED 5.6 and the first lens 7.8 in FIG. It is an enlarged perspective view. In addition, in FIG. 2 (al), L
5L6 is the optical axis of the emitted light of each LED 5.6.

As is clear from the figure, the first lens 7.8 in this embodiment has a curved surface in the direction in which the line sensors 2a are arranged. , respectively, one side that does not face the other lens 8.7, that is, the 7a side in the case of the first lens 7, and the 8a side in the case of the first lens 8, where the radius of curvature of the curved surface is small; That is, in the case of the first lens 7 7 b
In the case of the first lens 8, the radius of curvature of the curved surface on the 8b side is made large.

Therefore, the control state of the light emitted from the LED 5 or 6 by the first lens 7.8 is as shown in FIG.
As shown by the broken line in , the light passing through the sides 7a and 8a of the first lens 7°8, which have a smaller radius of curvature, has a steep slope.
The light passing through the sides 7b and 8b having a large radius of curvature is controlled to have a gentle slope.

Therefore, when the LED 5.6 is turned on, the first lens 7.8
The composite illuminance distribution due to the light emitted through is shown in Figure 2 (al
As shown by the solid line, the brightness distribution is almost uniform between L and ED5.6 in the arrangement direction.

That is, the first lens 7.8 controls the light emitted from the LEDs 5.6 in the arrangement direction of the LEDs 5, 6.

By controlling the radius of curvature in the row arrangement direction of the line sensors 12a, for example, the composite illuminance distribution shown by the solid line above can be changed as shown by the dashed line in FIG.
In other words, it goes without saying that it is possible to easily control the peripheral area to be brighter than the central area.

FIG. 3 (Tal) is a perspective view of the lens member used as the second lenses 9, 10, and FIG.

Note that L in FIG. 3 Ta) indicates the optical axis of the light emitted from the LED 5 or 6.

As is clear from the figure, the second lens 9.10 has a curved surface in a direction perpendicular to the row arrangement direction of the line sensors 12a, and the radius of curvature of this curved surface is the smallest along the optical axis. The size gradually increases from the optical axis position toward both ends.

In this embodiment, as is clear when considered in conjunction with FIG. , and the optical axes of the two are arranged so that their optical axes are shifted from their centers to the periphery.

It goes without saying that this is because it takes into consideration that the direction in which the line sensors of the reading section 12 are formed and the light between the LEDs 5 and 6 is used as illumination light for the object 11 to be read.

Therefore, the radius of curvature of the second lenses 9 and 10 described above is designed to increase the rate of change toward the side facing the other second lens, taking into consideration the distance from the LEDs 5 and 6.

Meanwhile, the second lens 9.10 as described above is connected to the LED 5.
6, the light emitted from the LEDs 5 and 6 is transmitted through the second lens 9 as shown in FIG. 4 (al).
. For reference, if we look at the case where a lens member with the same radius of curvature is combined with LED 5.6, it will depend on the distance from LED 5.6, but if they are placed close together for miniaturization, the fourth As shown in Figure fb), the light emitted from the LEDs 5 and 6 is controlled to have a substantially barrel shape with a bulge in the center.

That is, the lens member in this embodiment shown in FIGS. 3 (fat, fb) can condense the light emitted from the LED into a more preferable illuminance distribution state as an optical reading device.

In this embodiment, by providing the first lens 7° 8 as described above and the lenses 9 and 10 shown in FIG. 2 between the LEDs 5 and 6 and the object to be read 11, when the LED 5.6 is lit,
Illumination light condensed into a strip having a predetermined width can be supplied to the reading target 11 in the arrangement direction, that is, in the same direction as the line forming direction of the line sensors.

Note that it is also easy to control the illumination light so that the peripheral area is brighter than the central area.

In addition, in this embodiment, the optical axis L of the light emitted from the LED 5.6 is
5. L6 is assumed to be parallel, but for example, although not shown, the combined parts of the LEDs 5, 6, the first lens 7° 8, and the second lenses 9, 10 are tilted to each other, and the same injection as before is made. It goes without saying that the optical axes may intersect at an appropriate point on the reading target 11 side.

Furthermore, in this embodiment, the first lens 7.8 and the second lens 9.10 are used independently, but
For example, as shown in FIG. 5, the bottom surfaces of the first lens 7.8 and the second lenses 9, 10 may be connected and integrated to form one optical component. Needless to say.

In addition, in the case of this embodiment, there is a possibility that the illuminance distribution cannot be controlled to a desired state depending on the design/manufacturing or installation accuracy of lens members, etc., but the inclination of the optical axis of the light emitted from the LED 5.6 It would be better if it could be adjusted. In other words, although each member is, in principle, fixed to the main body of the optical reading device, for example, the inclination of the LED 5, 6 alone or the part combined with the first lens 7, 8, etc. is adjusted in principle. If the problem can be adjusted as appropriate at a fixed position, this can be adequately addressed.

In addition, there is a concern that the brightness of individual LEDs may not match or the brightness may be insufficient, but it is necessary to provide an adjustment circuit that adjusts the current flowing through the LEDs as in the conventional example mentioned at the beginning. The discrepancy in brightness can be adjusted, and the brightness itself does not pose any particular problem considering recent increases in the brightness of LEDs and high sensitivity of line sensors.

[Embodiment 2] FIG. 6 is a plan configuration diagram showing the basic structure of a second embodiment of the present invention, and in the figure, elements with the same symbols as in FIG. 1 indicate the same constituent members.

In this embodiment, one LED 13 is used as a light source, and this LED
Two types of optical members are arranged in front of the LED 13 and control the irradiation state of the light emitted from the LED 13, namely, a first
The basic structure includes an optical member 14 and a second optical member 15.

Note that in this embodiment, as in the first embodiment described above, the LED 1
It goes without saying that the object to be read 11 illuminated by the lighting of No. 3 is optically read by the reading section 12. The second optical member 14.15 will be explained.

First, regarding the first optical member 14, FIG.
An enlarged perspective view of AT and an enlarged plan view of BL in the same figure. is configured to become smaller as it moves away from the optical axis L13.

It is also clear from the figure that the direction in which the curved surface is formed is the same as the direction in which the line sensors 12a are arranged in rows.

With the above configuration, the illuminance distribution of the light emitted from the LED 13 has uniform brightness over an appropriate range, as shown by the solid line in FIG. 6 fb).

In addition, by varying the radius of curvature in the opposite direction of the optical axis L13100, that is, by controlling the degree of concavity at the top part, as shown by the dashed line in FIG. Needless to say, it is easy to obtain a bright illuminance distribution in the peripheral area.

Next, regarding the second optical member 15, FIG.
As shown in the enlarged perspective view of al and the Y-Y' cross-sectional view of fbl in the same figure, the row array of line sensors 12a ``I5self** is formed in the row arrangement ``1ulJA*'' gradually toward both ends of the subtotal 1. It is structured so that it grows in size.

That is, similarly to the second lens 9.10 in the first embodiment described above, the light emitted from the LED 13, which is focused and controlled by the first optical member 14, is transferred to the line sensor array of the reading unit 12. It has a function of condensing light into a band shape having a predetermined width in the same direction.

Therefore, this second embodiment also applies to the first embodiment. By providing the second optical member 14.15 between the LED 13 and the reading object 11, illumination light condensed into a strip having a predetermined width in the same direction as the line sensor row forming direction is transmitted to the reading object 11.
1 can be supplied.

It goes without saying that the illumination light can be made brighter in the peripheral area than in the central area, if necessary.

Furthermore, as for the concern about insufficient brightness due to the use of only one LED as a light source, as mentioned above, there is no problem considering that the brightness of the LED can be increased.

Furthermore, the first example in this embodiment. Second optical member 14.
15 can also be integrated, for example, by connecting their respective bottom portions.

The embodiments in which the number of LEDs serving as light sources is two and one have been described above, but the optical reading device according to the present invention transmits light emitted from the LEDs into a line between the LEDs serving as the light source and the object to be read. It is characterized by being equipped with an optical member that controls light condensation in two directions, one in the same direction as the direction in which the sensor array is formed, and one in a direction perpendicular to the direction in which the sensor array is formed.For example, when the object to be read is spread over a wide range, two or more LEDs are used. It goes without saying that it is okay to do so.

That is, the above-mentioned emitted light is placed in front of each of the two or more LEDs so that when each of the two or more LEDs is turned on, the combined illuminance distribution of the respective emitted light is similar to the illuminance distribution obtained in the first embodiment, etc. By arranging an optical member that controls condensation in two directions, it is possible to obtain an optical reading device according to the present invention that can illuminate a wide range of objects to be read in a desired state.

In addition, in the above case, variations in illuminance distribution due to inconsistency in the brightness of individual LEDs or manufacturing precision of optical components, etc. can be avoided by providing a brightness adjustment circuit or
Needless to say, this problem can be adequately addressed by adjusting the optical axis of the light emitted from the ED.

Effects of the Invention According to the present invention, an optical reading device includes an optical member between an LED serving as a light source and an object to be read, which controls condensation of light emitted from the LED in two directions so as to achieve a desired emission state. Because of this, the light emitted from the LED can be used efficiently, and therefore, it has the effect that illumination light having the amount of light necessary for illuminating the reading object can be obtained with a small number of LEDs. There is.

In addition, since the number of required LEDs can be reduced, the installation work can be simplified. In other words, when adjusting the installation state of LEDs and optical components, the number of adjustments is reduced, and furthermore, the brightness correction circuit is required for each LED. Even when provided, the number of correction circuits and the number of correction operations are reduced, and the entire device can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a plan configuration diagram showing the basic structure of the first embodiment of the optical reading device according to the present invention, and FIG. 2 (al shows only the LED 5.6 and first lens 7.8 of the first embodiment) FIG. 3 (b) is an enlarged perspective view of a lens member used as the first lens 7.8, and FIG. An enlarged perspective view of the lens member shown in FIG.
Transverse cross-sectional view, FIG. 4 (Al is a state diagram of condensing control of the emitted light from LED 5.6 when LED 5.6 and second lenses 9, 10 are combined, fbl beam in the same figure, ED5.
FIG. 5 is a condensing control state diagram of the emitted light from the LED 5.6 in the case of combining the lens member with the same radius of curvature. FIG. 9 is an enlarged perspective view showing an example of an integrated lens member forming a lens 9.10. FIG. 6 is a plan configuration diagram showing the basic structure of the second embodiment of the optical reading device according to the present invention, and FIG. 7 (al is an enlarged perspective view of the first optical member 14 of the second embodiment; bl is an enlarged plan view, FIG. 8 fat is an enlarged perspective view of the second optical member 15 of the second embodiment, and fbl is the same <YY' cross-sectional view. bl is a main part configuration diagram showing the main part configuration of the illumination means in a conventionally well-known optical reading device. 5.6...LED, 7.8... First Lens, 9.10...Second lens, 11...
...Reading target, 12...Reading section, 13...
...LED, 14...First optical member, 1
5...Second optical member. Name of agent Patent attorney Shigetaka Awano and one other person Figure 1 (θ) (b) +2-2A k Figure 7 (θ) Hitls (b) ■Lt3 Figure 7 Storage --- 15-Collection material (0 nhi excitation Y' (b)

Claims (10)

[Claims] (1) A reading section that optically reads the object, including a light source that is a high-intensity red light emitting diode that illuminates the object to be read, such as a bar code, and a line sensor that receives reflected light from the object to be read; A belt-shaped device is disposed between a light source and the object to be read, controls to focus the light emitted from the light source in two directions, the same direction and the orthogonal direction to the line forming direction of the line sensor, and has a strip shape having a predetermined width. An optical reading device comprising an optical member that emits illumination light for the object to be read. (2) The optical member includes a first optical member that focuses and controls the emitted light from the light source in the same direction as the line forming direction of the line sensor, and a first optical member that controls the emitted light in a direction perpendicular to the line forming direction. Claim (1) comprising a second optical member for controlling light collection.
optical reader. (3) A light source that illuminates the object to be read such as a barcode 2
a reading unit that optically reads the reading target, including a line sensor that receives reflected light from the reading target; and a reading unit that optically reads the reading target; placed between the target and
a first lens that controls condensation of light emitted from the high-intensity red light-emitting diodes in the same direction as the line forming direction of the line sensor; each of the two high-intensity red light-emitting diodes and the reading target; and a second lens that controls the emitted light in a direction orthogonal to the row forming direction, and supplies a strip-shaped illumination light having a predetermined width to the reading target. reading device. (4) The first lens has a curved surface formed in the row arrangement direction of the line sensors, and the curved surface on one side that does not face the other lens has a small radius of curvature, and the one side that faces the other lens has a small radius of curvature. 4. The optical reading device according to claim 3, wherein the curved surface has a large radius of curvature. (5) The second lens has a curved surface formed in a direction perpendicular to the row arrangement direction of the line sensors, and the radius of curvature of the curved surface is the smallest at the optical axis position of the light emitted from the high-intensity red light emitting diode, and the 4. The optical reading device according to claim 3, wherein the radius of curvature of the curved surface gradually increases from the axial position toward both ends. (6) The optical reading device according to claim (3), wherein the first lens and the second lens are integrally connected at appropriate locations. (7) Light source 1 that illuminates the object to be read, such as a barcode
a reading section that includes a line sensor that receives reflected light from the object to be read, and optically reads the object to be read; a first optical member disposed between the high-intensity red light-emitting diodes and controlling the condensation of light emitted from the high-intensity red light-emitting diodes in the same direction as the row formation direction of the line sensor; a second optical member disposed between the diode and the object to be read and controlling the condensation of the emitted light in a direction perpendicular to the column forming direction; An optical reading device that supplies light to the object to be read. (8) The first optical member has a curved surface having a radius of curvature that is symmetrical in the row arrangement direction of the line sensors with respect to the optical axis of the emitted light from the high-intensity red light emitting diode, and a partially flat portion; The optical reading device according to claim 7, wherein the radius of curvature becomes smaller as the distance from the optical axis increases. (9) The second optical member has a curved surface formed in a direction perpendicular to the row arrangement direction of the line sensors, and the radius of curvature of the curved surface is smallest at the optical axis position of the high-brightness red light emitting diode and gradually increases toward both ends. The optical reading device according to claim 7, wherein the optical reading device is configured to increase in size. (10) The optical reading device according to claim (7), wherein the first optical member and the second optical member are integrated in a manner where appropriate portions are connected.