JP2932815B2 - Optical information reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading apparatus for reading optical information such as a bar code, and more particularly to an optical information reading apparatus capable of reading an object to be read having a diameter larger than a reading aperture.

[0002]

2. Description of the Related Art Heretofore, an object to be read such as a label on which optical information such as a bar code or an OCR character is recorded is irradiated with illumination light by illumination means, and an information image based on the reflected light is formed into an optical system for imaging. There is known an optical information reading apparatus that forms an image on the surface of a reading means (image sensor) by using a digital camera and converts the image into an electric signal by reading operation of the reading means by an electronic scanning method.

[0003] When an operator performs reading by moving the reading device itself, it is difficult for the operator to understand the scanning position, and he mainly relies on intuition, so that the scanning position cannot be adjusted to the target reading object. However, when the reading targets are densely packed, there is a problem that another reading target is read by mistake. For this reason, guide light is emitted from a part of the surface of the reading means, specifically, both ends of the reading line, and guide light is displayed on the reading object through the imaging optical system to recognize the current reading position and the readable range. It is known that it is possible to recognize whether or not the focal length is in accordance with the size of the guide light display, the contrast, and the like (for example,
See, for example, JP-A-63-184179) .

[0004]

[0005]

[0006]

However , the above-described guide light display allows the operator to recognize the current scanning position, the readable range, and the defocus, but the optical information is required to read a large reading target. If the distance between the reading device and the object to be read is increased, the guide light display becomes large and dark, and if the surrounding environment is bright, the guide light display itself cannot be determined.

The present invention has been made in view of such a problem, and has a guide light display regardless of a distance from an object to be read.
It is an object of the present invention to provide an optical information reading device capable of reliably determining the information.

[0008]

That is, an optical information reading apparatus according to the present invention, which has been made to achieve the above object, comprises: an irradiating means for irradiating an object to be read with optical information with light; An image forming optical system for forming an image of an information image by reflected light reflected from the object to be read at a predetermined reading position, and converting the image information into an electric signal by an electronic scanning reading operation, in optical information reading apparatus having a reading means for reading information, than the optical system for the imaging provided in the read object side, guide performing guide light display the guide light is irradiated on the surface of the reading target Light display means.

In the optical information reading apparatus of the present invention configured as described above, the irradiating means irradiates light to the reading object on which the optical information is described, and reflects the light from the reading object by the imaging optical system. The information image formed by the reflected light is focused on a predetermined reading position, and the reading means converts the image information into an electric signal by an electronic scanning type reading operation to read optical information.

At the time of reading, the guide light display means irradiates the surface of the object with the guide light to perform the guide light display, so that the current scanning position and the readable range can be understood at a glance, and the target object to be read can be surely detected. Can be scanned. And
The guide light display means is provided closer to the reading object than the imaging optical system, and does not pass through the imaging optical system unlike the conventional one. Therefore, even if the distance between the reading device and the object to be read is increased, the display of the guide light on the object to be read is large, and as a result, the display is hardly dark, and the display of the guide light can be reliably determined.

[0011]

[0012]

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway cross-sectional view of a handy type bar code reader 1 configured as an embodiment of the optical information reading apparatus of the present invention. As shown in FIG. 1, the bar code reader 1 includes a power supply 8, a control unit 10, an illumination LED 21 as an irradiation unit, a condenser lens 23, a plane reflecting mirror 25, an imaging lens 27, and a one-dimensional solid-state imaging device. An image sensor 29, a guide light source 31, a distance sensor 33, a buzzer 35, a trigger switch 37 and the like are provided.

The illuminating light from the illuminating LED 21 is passed through the condenser lens 23 so that the light is focused on a reading target 40 on which optical information such as a bar code B is written. Then, the reflected light from the reading object 40 is reflected by the plane reflecting mirror 25 and guided to the image forming lens 27, and the image forming lens 27 is displayed on the image sensor 29 at a predetermined position on the image sensor 29 (in this embodiment, a bar code). Image). The control unit 10 reads an electric signal corresponding to the formed information image, performs amplification processing, binarization processing, and decoding processing to decode optical information.

The above-mentioned imaging lens 27 is made movable in the main optical axis direction by a lens moving knob 43. The guide light source 31 is located closer to the plane reflecting mirror 25 than the imaging lens 27.
Is reflected by the plane reflecting mirror 25 without passing through the imaging lens 27, and forms an image on the reading target 40. The guide light source 31
For example, a light emitting diode, a laser, or the like may be used.

The distance sensor 33 measures the distance between the bar code reader 1 and the object 40 to be read, and is provided near the reading opening of the bar code reader 1. The buzzer 35 is for informing the operator that sound is focused on the image sensor 29 by sound.

Next, the operation when the bar code B is read using the bar code reader 1 of this embodiment will be described. The guide light from the guide light source 31 is applied to the surface of the reading target 40 to perform the guide light display. FIG. 1 shows two guide light sources 31. By irradiating guide light GL to both ends of the bar code B, the operator can read the current scanning position of the bar code reader 1 and read. It is made possible to know the possible range.

The number of the guide lights GL and the positions to which the guide lights GL are applied are not limited to the case where the guide lights GL are applied to both ends of the bar code B as shown in FIG.
Various types are conceivable as shown in (B) to (D). As described above, the current scanning position and the readable range can be recognized at a glance by the guide light GL, and the target scanning target can be reliably scanned.

The guide light source 31 is provided closer to the plane reflecting mirror 25 than the image forming lens 27, that is, closer to the object 40 to be read, and does not pass through the image forming lens 27. Even if the distance from the reading target 40 is large, the guide light GL on the reading target 40 does not become so large that the guide light GL becomes dark, so that it is possible to reliably determine the guide light GL.

After the bar code reader 1 is pointed at the object 40 to be read using the guide light GL, the trigger switch 37 is pressed and the distance sensor 3 is pressed.
3 operates to measure the distance between the reading target 40 and the barcode reader 1. The control unit 10 determines whether or not the image information formed on the image sensor 29 is in focus based on the measured distance. If not, the control unit 10 sounds the buzzer 35 to inform the operator. Inform. The operator operates the lens moving knob 43 to move the imaging lens 27 to focus. Specifically, it may be moved to a position where the buzzer 35 does not sound.

When the trigger switch 37 is pressed,
Illumination light from the illumination LED 21 is applied to the reading target 40, and an information image of the barcode B is formed on the image sensor 29 by the reflected light. The image sensor 29 generates an electric signal according to the intensity of the reflected light and sends it to the control unit. As described above, the control unit 10 amplifies, binarizes, and decodes the electric signal. Becomes weaker,
Conversion to barcode data may not be possible. The determination as to whether or not the conversion into the barcode data can be made can be made, for example, by comparing the amplified electric signal level with a predetermined lower limit.

Accordingly, the control unit 10 increases the signal level by extending the exposure time of the image sensor 29 or increasing the amplification factor, but the control unit 10 may not yet reach the lower limit. In this case, the lighting LED 2
1 is increased, the reflected light from the reading target 40 is further increased, and decoding is performed.

Conversely, there are cases where the surroundings are too bright and the reflected light from the object 40 is too strong, the electric output of the image sensor 29 is saturated, and the bar code B image cannot be accurately converted to an electric signal. . In this case, the lighting L
The brightness of the ED 21 is reduced so that the electric output of the image sensor 29 is not saturated. If decoding is not possible even when the illumination LED 21 is turned off, control is performed such that the exposure time is shortened or the amplification factor is reduced so that the signal level falls below a predetermined upper limit.

As described above, in addition to the adjustment based on the change in the exposure time and the amplification factor, the luminance itself of the illumination LED 21 is changed so that the electric signal level of the light receiving element of the image sensor 29 falls within the proper range in which decoding is possible. In this case, it is possible to prevent a reading error of the bar code B on the reading target 40 and obtain sufficient reading performance. Note that the guide light display, the operation of the distance sensor 33, and the illumination light from the illumination LED 21 can be obtained. Irradiation, trigger switch 3
The operation may be started at the same time when 7 is pressed.
Further, for example, when the control unit 10 determines that the image information formed on the image sensor 29 is in focus, the guide light source 31 may be turned off once. Then, again, the trigger switch 37
If the light is turned on when is pressed, the reading range and the like can be similarly known for the next bar code B.

As described above, when optical information is read, the guide light GL is irradiated on the surface of the object to be read, and the guide light is displayed. Can be reliably scanned. The guide light source 31 is located closer to the reading target 40 than the image forming lens 27 and does not pass through the image forming lens 27 unlike the conventional one. Therefore, even if the distance between the barcode reader 1 and the read target 40 is increased, the guide light display on the read target 40 becomes large and the guide light is hardly darkened.

Also, based on the distance measured by the distance sensor 33, it is determined whether or not the imaged image information is in focus. The reflected light may be too strong or too weak depending on the distance of the camera and the surrounding brightness. On this occasion,
In this embodiment, in addition to the change in the exposure time and the amplification factor, the luminance of the illumination LED 21 is also changed so that the electric signal level in the reading means is controlled to be within an appropriate range. Therefore,
Irrespective of the brightness of the surroundings, the object to be read is illuminated with an appropriate luminance, and it is possible to prevent poor reading of optical information on the object to be read and obtain sufficient reading performance.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various modes without departing from the gist of the present invention. For example, the means for informing the operator whether or not the image sensor 29 is in focus is not limited to the above-described buzzer 35, and a visual appeal may be made by using a light emitting diode, or both may be used. And appeal to the sense of sight and hearing.

Further, the imaging lens 27 is moved in the main optical axis direction by the lens moving knob 43.
The motor may be used to automatically focus. Further, although the exposure time of the image sensor 29 is changed, a sensor having a shutter function such as an electronic shutter may be used.

[0029]

As described above, according to the optical information reading apparatus of the present invention, regardless of the distance from the object to be read.
There is an effect that the guide light display can be reliably determined .

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view of a handy type bar code reader configured as one embodiment of an optical information reading apparatus of the present invention.

FIG. 2 is a schematic explanatory view showing the number of guide lights and the position of the guide light applied to a bar code.

[Explanation of symbols] B: bar code, GL: guide light, 1
... Bar code reader, 10 ... Control unit,
21: LED for illumination, 23: Condensing lens, 25: Flat reflecting mirror, 27: Image forming lens, 29: Image sensor, 31: Guide light source, 33: Distance sensor, 35: Buzzer, 37: Trigger switch,
40 ... read target

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tadao Nojiri 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside Denso Corporation (72) Inventor Kunihiro Takada 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nihon Denso Co., Ltd. (72) Inventor Kunihiro Mochizuki 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Koji Kosusu 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nihon Denso Co., Ltd. (72) Inventor Takeshi Watanabe 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture, Japan Denso Co., Ltd. (72) Inventor Akio Sugiura 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture, Japan Denso Co., Ltd. (56) References JP-A 63-83886 (JP, A) JP-A-3-103994 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06K 7/015 G06K 7/10

Claims (1)

(57) [Claims] 1. An irradiating means for irradiating a reading object on which optical information is described with light, and an imaging optical system for forming an information image by a reflected light reflected from the reading object at a predetermined reading position. If, converts the image information into an electric signal by the reading operation of the electronic scanning method, in an optical information reading apparatus having a reading means for reading the optical information, the read than the optical system for the imaging target An optical information reading device, comprising: a guide light display unit provided on a side of the device to illuminate the surface of the object to be read with guide light to perform guide light display.