JPS60235277A - Optical information reader - Google Patents

Abstract

PURPOSE:To read accurately information even if the brightness is changed considerably, by switching and adjusting the aperture area of an aperture member, which is provided with a liquid crystal changing the aperture area and is set in the optical path, in accordance with the intensity of light in a bar code reader. CONSTITUTION:The illuminated light of a light emitting diode 1 is irradiated to a bar code label 4 through a light scattering member 3, and the reflected light is focused onto an image sensor 9 through an optical system consisting of a lens 7 and an aperture member 8. When a voltage is applied to a transparent electrode film of the aperture member 8, the axis of molecules of the liquid crystal layer is changed with respect to the arrangement direction, and the light transmittance is reduced. The applied voltage is controlled by the signal of an electronic control circuit 11 of the image sensor 9 to correct the quantity of light incident on the image sensor 9 to a proper value, and the bar code is read in a uniform level even if the ambient illuminance is high.

Description

[Detailed Description of the Invention] [Industrial Application Field] (1) The present invention relates to barcodes printed on recording media such as labels,
The present invention relates to an optical information reading device that reads optical information such as characters.

[Prior art]

Conventionally, this type of device uses illumination means to irradiate illumination light onto a label on which optical information such as a barcode or text is recorded, and an information image created by the reflected light is formed on the surface of a reading sensor (image sensor). The image is then converted into an electrical signal by the sensor's electronic scanning reading operation. With this lighting method, there is no problem when reading in a normal usage environment (such as an office with a brightness of about 1,000 Rx), but in different environments such as outdoors, the brightness of the surroundings may make it difficult to read the label. The reflected light changes greatly.

In other words, the usage environment was limited.

[Wi problem that the invention attempts to solve]

The present invention solves the above problem, and uses a normal reading sensor to enable normal reading of optical information in various usage environments, especially in environments where brightness greatly differs. 2) The purpose is to

[Failure to solve the problem]

To this end, the present invention provides an optical information reading device equipped with a reading sensor in which photo elements are arranged to convert an information image into an electric signal through an electronic scanning type reading operation, in which the information image is imaged at a reading position. an aperture member equipped with a liquid crystal whose aperture area changes and is installed in the optical path of an imaging optical system for the purpose of controlling the image formation; The configuration is such that a switching means is provided.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

Fig. 1 is a partial cross-sectional configuration diagram of the same, where 1 is a red light-emitting light with a brightness of 'i11+ used for the light source that constitutes the illumination means, and 3 is a light scattering material that scatters the illumination light from the red light-emitting diode 1. It is made uniform over a predetermined range. 4. Barcode of optical information on the label of the recording medium 5.
is printed.

Reference numeral 6 denotes a flat reflecting mirror, which reflects the (j3) anti-1.] light from the barcode label 4 to change its direction. A lens 7 forms the reflected light from the barcode label 4, and a diaphragm member 8 is used to image the barcode image at a predetermined reading position. A liquid crystal is used in this diaphragm section +)fB, and the diaphragm area is controlled so as to provide optimal transmitted light according to the intensity of reflected light.

Reference numeral 9 denotes an image sensor as a reading sensor, which has a one-dimensional decomposition function of 1024 bis, 1, in which many photo elements are arranged in a line, and has a spectral sensitivity near the emission spectrum of the red light emitting diode 1. It has a peak area.

Reference numeral 10 denotes a hand-held case, which is connected to a data processing device via a signal cable for transmitting and receiving various electrical signals between the inside and outside of the case. 11 is an electronic control circuit for the image sensor 9.

Figure 2 is a detailed view of the optical path f (13 minutes) in -F. Figures 3 (A) and (B) are structural diagrams of the aperture member using liquid crystal. The frame body 8a has an elliptical aperture window 8g and has a rectangular plane.The aperture windows 8g are a, b.

(4) It is divided into three aperture areas of C, and a and b are each (B
) has the structure shown in the cross-sectional view. This aperture member has a pair of polarizing plates 8b and a transparent glass substrate 8C in portions a and b, respectively.

Furthermore, a transparent electrode film 8 is provided on the inner end surface of the transparent glass substrate 8C.
f are formed and held at constant intervals by spacers 8d to form parallel plate capacitor-like cells. A liquid crystal layer 8e is provided inside the cell, and its transparent electrode 1%8
f is connected to the electronic control circuit 11.

Next, the operation of the above configuration will be explained.

Now, the reading device is hand-held at the position shown in FIG. 1 relative to the barcode label 4, and the high-intensity red light-emitting diode 1 is turned on to emit light. The red illumination light generated by this emission passes through the light scattering material 3 and is irradiated onto the barcode label 4. With this light illumination, the own bar on the barcode label 4,
The reflectance differs according to the black bar, and the light intensity distribution passes through the optical system of the lens 7 and the aperture member 8 corresponding to the barcode 5, and passes through the reading line (5) where the photo elements of the image sensor 9 are lined up.
) to form a barcode label image of each bar in the orthogonal direction.

Therefore, the barcode image can be converted into an electrical signal by the electronic scanning reading operation by the electronic control circuit 11 of the image sensor 9.

Here, changes in the environment around which the reading device is used become a problem. For example, when a reading device is used in a 1ffl office, the general brightness is about 1,000βX, but when used near a window, the brightness reaches 10 to 100 times that amount. It is difficult to accommodate this dynamic range in an amplifier! lE
It is.

Therefore, the aperture area of the liquid crystal is 1I in the aperture member 8 of the optical path.
Equipped with Iliil adjustment function. That is, when a voltage is applied to the transparent electrode FI8f of the diaphragm member, the molecular axes of the liquid crystal layer 8e change their alignment direction, and the diaphragm area becomes smaller and the light transmittance decreases. As a result, the light M reaching the image sensor 9 is reduced, resulting in an aperture effect.

FIG. 4 shows a characteristic diagram, which shows an example of the change tendency of transmittance (relative value) depending on the applied voltage of the liquid crystal.

(6) Here, due to the influence of the polarizing plate 8b, which is a component of the aperture member, the maximum value of transmittance is suppressed to about 30% (at this time,
(The range of change in transmittance is about 1.5 to 30%) However, due to the sensitivity characteristics of the image sensor and the amplifier, the S/N ratio is not impaired even by inserting the aperture member 8.

FIG. 5 shows a block diagram showing the detailed configuration of the electronic control circuit 11. The electric signal from the image sensor 9 is sent to the amplifier 11.
In addition to a series of reading circuits consisting of a sample bold llb, a low-pass filter 11, a C1 binarization circuit lid, and a comparator 1.1. The liquid crystal a of the diaphragm member 8 is
, b. In this case, parts a and b.

By dividing into C, the aperture can be adjusted in three ways as shown in FIG. For example, if the diameter ratio of the ellipse is 1:2:3, the aperture ratio (area ratio) Q is 1 in (A), 0.44 in (B), and (
In C), Q=0.11, which corresponds to about 10 times the Dairy Miso clean range (7).

Therefore, the applied voltage, that is, the degree of aperture is controlled by the signal of the electronic control circuit 11 of the image sensor 9, and the amount of light sent to the image sensor 9 is corrected to an appropriate amount even under conditions of high ambient illumination, so that reading can be performed at a uniform level. is possible.

Here, as an example, the aperture adjustment position using the liquid crystal is arranged on the aperture member 8, but this can be changed to another optical path, for example, as shown in FIG. You may.

Further, although the degree of aperture by the liquid crystal was controlled by the electronic control device, a manual switching switch/notch may be provided.

Further, although a hand-held type reader is illustrated as an example, the present invention may be applied to a stationary type reader in which only the barcode label 4 is moved.

Moreover, although the barcode 5 is used as the optical information as an example, other codes, characters, etc. may be used as the optical information.

Further, although a linear one-dimensional image sensor (8) is illustrated as the reading sensor 9-, other sensors such as a planar two-dimensional image sensor (TV camera, etc.) or an optical film may be used.

〔Effect of the invention〕

As described above, the present invention has the excellent effect of being able to easily and highly accurately read optical information at a uniform level under various usage environments using a normal reading sensor. be.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a detailed view of the optical path part in Figure 1, Figure 3 is a cross section showing the configuration of the diaphragm member, Figure 4 is a characteristic diagram for explaining the operation, and Figure 5 is the detailed configuration of the electronic control circuit. FIG. 6 is an explanatory diagram of the operation of the liquid crystal of the diaphragm member, and FIG. 7 is a block diagram showing the main part of another embodiment of the present invention. 1... Red light emitting diode serving as a light source of the illumination means, 3
... light scattering material, 4 ... barcode label as a recording medium, 5 ... barcode of optical information, 6 ... plane reflecting mirror, 7 ... lens, 8 ... aperture member , 9...
・Reader (9) Image sensor as a sensor, 10... Handheld case,
11...Electronic control circuit. Representative Patent Attorney Takashi Okabe (10); εC3 Ro rr

Claims (1)

[Scope of Claims] An illumination means for illuminating optically recorded information to be read, and an imaging optical system for forming an information image by light reflected from the information to be read by the illumination at a predetermined reading position. , an optical information reading device equipped with a reading sensor arranged at this reading position and having an array of photo elements that convert the information image imaged on its surface into an electric/electrical signal by an electronic scanning type reading operation. , a diaphragm member provided in the optical path of the imaging optical system and equipped with a liquid crystal whose diaphragm area changes; and a switch that switches and adjusts the diaphragm area of the diaphragm member according to the light intensity of the information image. 1. An optical information reading device comprising: means.