JP2815809B2 - Information reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage recording section in which light from a light source is made incident on a polygon mirror and travels after being reflected by the polygon mirror. The present invention relates to an information reading apparatus for sequentially projecting light toward a recording unit, causing reflected light reflected and returned by each recording unit to enter a light receiving unit, and reading information recorded in each recording unit.

[0002]

2. Description of the Related Art For example, as an information reading apparatus for reading bar code symbols, a semiconductor laser as a light source, a polygon mirror that reflects laser beam light from the semiconductor laser to produce scanning light, and a polygon mirror that reflects light from the polygon mirror. There has been known a device including a photodiode that receives reflected light reflected by a back bar code symbol and outputs a signal by receiving the reflected light. Some known barcode symbol information reading devices are configured such that the rotational position of a polygon mirror is slightly displaced from its central axis, thereby performing raster scanning.

[0003]

Among the bar code symbols to be read by such an information reading device, there are bar code symbols recorded in a plurality of stages, that is, two-dimensionally (hereinafter, this is a multi-stage bar code symbol). In the case of an information reading apparatus having the above-described configuration, for example, even if raster scanning is performed using a polygon mirror having an increased number of reflecting surfaces, an automatic reading operation is performed. Is very difficult. For example, when reading a multi-stage barcode symbol composed of N-stage barcodes, at least the same number of scanning lights as the number N of scanning steps is required. Cannot be done. In view of the above circumstances, an object of the present invention is to provide an information reading device that can automatically and reliably read information recorded in multiple stages without omission.

[0004]

According to the first aspect of the present invention, light from a light source is made incident on a polygon mirror, and a plurality of scanning lights traveling after being reflected by the polygon mirror are transmitted to a multi-stage recording section. An information reader that sequentially emits light toward each of the recording units on which information is recorded in parallel, makes reflected light reflected by each of the recording units incident on a light receiving unit, and reads information recorded on each of the recording units. The apparatus further includes a vibrating means for vibrating a motor for rotating the polygon mirror at a specific frequency and a specific shake angle with respect to the rotation speed of the polygon mirror.

According to a second aspect of the present invention, the rotation axis of the polygon mirror is deviated by a predetermined angle with respect to the output shaft of a motor for rotating the polygon mirror.

[0006]

According to the first aspect of the present invention, a specific relational expression having a fixed relation between the distance between the polygon mirror and the recording unit, the swing angle of the motor, the interval between the recording units in each stage, and the like is obtained. By operating the vibrating means satisfactorily, the raster scanning light is emitted toward the portion where the recording sections are arranged in multiple stages, and the information recorded in each recording section can be read without omission.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view showing an information reading apparatus according to a first embodiment of the present invention. This information reading apparatus comprises a light source 1, a polygon mirror 2, a motor 3
And vibration generating means 4. Reference numeral 5 indicates a two-dimensional barcode symbol, and in this embodiment, it is composed of N stages.

In this embodiment, a light source 1 uses a semiconductor laser (LD). A light beam emitted from the light source 1 is collimated by a collimator lens 11 and then collimated.
The light is reflected by the reflecting mirror 12 and enters the polygon mirror 2.

The polygon mirror 2 is rotatably driven by a motor 21. The polygon mirror 2 is attached to the rotation shaft 2 of the motor 21 with a slightly shifted center axis (angle α (rad), where α << 1). I have.

The motor 3 is mounted on a movable plate 31 which is vibrated by the vibrating means 4, so that when the vibrating means 4 does not operate, the motor 3 can stand still in a stable state. The movable plate 31 is provided with a rotation shaft 31 </ b> A at a central portion so as to rotate around a central portion where the motor 3 is mounted.

The vibrating means 4 has a constant frequency n (times / sec).
The elliptical cam 41 rotates in step c), and a motor 42 drives the elliptical cam 41 to rotate.
One end of the elliptical cam 41 is constantly pressed against the back surface of the movable plate 31 by the elastic force of 3. In addition, this vibrating means 4
The movable plate 31 vibrating in the above is configured so that the frequency n satisfies a certain condition as described later.

Next, the operating conditions of the movable plate 31 in the information reading apparatus according to this embodiment will be qualitatively described. First, for simplicity of explanation, it is assumed that the rotation center of the polygon mirror 2 attached to the output shaft 32 of the motor 3 is not shifted. Here, this operating plate 3
The frequency of 1 is n (times / sec), the number of scans by the polygon mirror 2 is N (times / sec), the distance from the polygon mirror 2 to the barcode symbol 5 is L (mm), and the movable plate 3
Assuming that the vibration angle of 1 is θ (rad), the deviation of the mounting angle of the polygon mirror 2 is α (rad), and the moving distance in the vertical direction per scan is X (mm), 2 · Ltan2θ · n / N = X Here, if θ << 1,

[0013]

(Equation 1)

The following holds.

Next, a description will be given of a raster scanning mechanism in which the polygon mirror 2 is mounted at a position shifted from the center position by an angle α (rad). Here, assuming that the number of surfaces of the polygon mirror 2 is M (surface), the condition for the timing of both the vibration operation of the movable plate 31 during scanning and the rotation operation of the polygon mirror 2 by the motor 3 is as follows: N = (k · M · n) (2) (where k is a natural number) Also, since the moving distance in the vertical direction in one scan is equal to that where the rotation center is not shifted, Conditions for (1),

[0016]

(Equation 2)

The above also holds true as it is.

Next, a second embodiment according to the present invention will be described. In this embodiment, the same parts as those in the previous embodiment are denoted by the same reference numerals, and redundant description will be avoided. The information reading apparatus shown in FIG. 2 includes a pressing shaft 44 for pressing the vibrating means 4 against the movable plate 31, a stepping motor 42 'for moving the pressing shaft 44 back and forth,
And control means 6 for driving 2 '(see FIG. 3).

As shown in FIG. 3, the control means 6 comprises a pulse generating circuit 61, a switching circuit 62, a motor driving circuit 63, and a current amplifying circuit 64.

The pulse generating circuit 61 is for generating a basic pulse for driving the stepping motor. For example, in this embodiment, a period T that satisfies the following equation, that is,

[0021]

(Equation 3)

It is configured to generate a pulse having a cycle that satisfies the conditions.

The switching circuit 62 moves the motor forward,
A switch for retreating is provided, and the input is connected to the output of the pulse generation circuit 61.

The motor drive circuit 63 is for generating a four-phase pulse for the stepping motor 42 ', and has an input connected to the output of the switching circuit 62.

The current amplifying circuit 64 is for amplifying the current flowing to the motor, and has an input of the motor drive circuit 6.
3 output.

In addition, as the vibrating means, in particular, the second
The configuration is not limited to that of the embodiment. For example, as shown in FIG.
The elliptical cam 41 'is directly connected to the motor 3 for driving the polygon mirror as shown in FIG.
May be mounted so that one motor 3 can perform two types of operations.

[0027]

As described above, according to the present invention, a fixed relationship is provided between the distance between the polygon mirror and the recording section, the swing angle of the motor, the interval between the recording sections in each stage, and the like. Activate the vibrating means so as to satisfy the specific relational expression, emit the raster scanning light toward the part where the recording units are arranged in multiple stages, and read the information recorded in each recording unit without omission. Therefore, the information recorded in multiple stages can be securely and accurately read without any omission.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an information reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing an information reading device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing control means of an information reading apparatus according to a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a modification of the present invention.

FIG. 5 is an explanatory view showing another modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Polygon mirror 3 Motor 4 Vibration means 5 2D barcode symbol

Claims (2)

(57) [Claims] 1. A light from a light source is made incident on a polygon mirror, and each scanning light, which travels after being reflected by the polygon mirror, is sequentially directed to each recording unit in which a plurality of information are recorded in parallel in a multistage recording unit. An information reading device that projects light, makes reflected light reflected by each of the recording units return to a light receiving unit, and reads information recorded in each of the recording units, wherein a motor that rotationally drives the polygon mirror is provided. An information reading apparatus, comprising: a vibrating unit that vibrates at a specific frequency and a specific shake angle with respect to the rotation speed of a polygon mirror. 2. The information reading apparatus according to claim 1, wherein the rotation axis of the polygon mirror is shifted by a certain angle with respect to the output shaft of a motor for rotating the polygon mirror.