JPH07334603A - Information reading device - Google Patents

Abstract

PURPOSE:To automatically and correctly read the information which is recorded in multiple steps by vibrating a motor that drives a polygonal mirror in a specific oscillation frequency and at a specific angle of deflection against the revolving speed of the polygonal mirror. CONSTITUTION:The oscillation frequency of a mobile plate 31 is set at n (times/see.) together with the scanning number of a polygonal mirror 2 set at N (times/see.), a distance L (mm) set between the mirror 2 and a bar code symbol 5, the vibrating angle of the plate 31 set at theta (rad), an attachment angle error of the mirror 2 set at alpha (rad), and a vertical shift distance set at X (mm) per scan respectively. Under such conditions, 2.Ltan2theta.n/N=X is satisfied. Then Napprox.=(2L.2theta).n/X is satisfied by setting theta<<1. Thus an oscillator means is actuated to satisfy the relational expression, and the raster scanning light is projected toward a part where the recording parts are prepared in multiple steps and in parallel to each other.

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 a plurality of scanning lights, each of which has a plurality of scanning lights which are incident on a polygon mirror and which are then reflected by the polygon mirror and which travel, are recorded. The present invention relates to an information reading device for sequentially projecting light toward a recording unit, causing reflected light reflected by each recording unit to return to 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 device for reading a bar code symbol, a semiconductor laser serving as a light source, a polygon mirror for reflecting laser beam light from the semiconductor laser as scanning light, and a polygon mirror for reflecting the laser beam light are scanned by the polygon mirror. There is known a device including a photodiode that receives reflected light that is reflected by the rear barcode symbol and returns, and outputs a signal. In addition, among the barcode symbol information reading devices, there is known a device in which the rotational position of the polygon mirror is provided slightly deviated from the central axis thereof to perform raster scanning.

[0003]

By the way, among the bar code symbols to be read by such an information reading device, a bar code recorded in a plurality of multi-steps, that is, two-dimensionally (hereinafter, this multi-step bar code symbol will be described). In the case of the information reading device having the above-described configuration, for example, even if the raster scanning is performed using an additional number of reflecting surfaces of the polygon mirror, the reading operation is automatically performed. Is very difficult. For example, when reading a multi-stage bar code symbol consisting of N stages of bar codes, at least the same number of scanning lights as the number of stages N is required. Therefore, even if only one bar deviates from the scanning light, an accurate reading operation is performed. Cannot be done. Therefore, in view of the above-mentioned circumstances, an object of the present invention is to provide an information reading device capable of automatically and reliably reading information recorded in multiple stages without omission.

[0004]

That is, according to the first aspect of the present invention, a multistage recording unit is provided with a plurality of scanning lights each of which is made to enter light from a light source into a polygon mirror and is reflected by the polygon mirror. Information reading that reads information recorded in each recording unit by sequentially projecting light toward each recording unit in which information is recorded and causing reflected light that is reflected by each recording unit to return to the light receiving unit The apparatus is provided with a vibrating unit that vibrates a motor that rotationally drives the polygon mirror at a specific frequency and a specific deflection angle with respect to the rotation speed of the polygon mirror.

The invention according to claim 2 is such that the rotation axis of the polygon mirror is deviated from the output axis of the motor for rotating the polygon mirror by a certain angle.

[0006]

According to the first aspect of the present invention, a specific relational expression that gives a certain relation to the distance between the polygon mirror and the recording portion, the swing angle of the motor, the distance between the recording portions of each stage, and the like is provided. The oscillating means is operated so as to satisfy the condition, and the raster scanning light is projected toward the portion where the recording portions are arranged in multiple stages, so that the information recorded in each recording portion 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 device according to a first embodiment of the present invention. This information reading device includes a light source 1, a polygon mirror 2, and a motor 3.
And a vibrating means 4. Reference numeral 5 indicates a two-dimensional bar code symbol, and in this embodiment, it is composed of N stages.

A semiconductor laser (LD) is used as the light source 1 in this embodiment, and the beam light emitted from the light source 1 is collimated by a collimator lens 11 and then collimated.
It is configured to be reflected by the reflecting mirror 12 and enter the polygon mirror 2.

The polygon mirror 2 is rotatably driven by a motor 21, and is attached to the rotary shaft 2 of the motor 21 with its center axis slightly displaced (angle α (rad), where α << 1). There is.

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

The vibrating means 4 has a constant frequency n (times / sec.
The elliptic cam 41 that rotates in c) and the motor 42 that rotationally drives the elliptic cam 41, and the spring 4
One end of the elliptical cam 41 is constantly in pressure contact with the back surface of the movable plate 31 by the elastic force of 3. In addition, this vibrating means 4
The movable plate 31 that vibrates at is configured so that the frequency n satisfies a certain condition as described later.

Next, the operating conditions and the like of the movable plate 31 in the information reading apparatus according to this embodiment will be qualitatively described. First, in order to make the explanation easy to understand, it is assumed that the polygon mirror 2 attached to the output shaft 32 of the motor 3 has its center of rotation not displaced. 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), the movable plate 3
When the vibration angle of 1 is θ (rad), the mounting angle deviation of the polygon mirror 2 is α (rad), and the vertical movement distance per scan is X (mm), 2 · Ltan2θ · n / N = X Here, if θ << 1,

[0013]

[Equation 1]

Is satisfied.

Next, a description will be given of a raster scanning mechanism in which the polygon mirror 2 is mounted by being displaced 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 conditions for both the timing of the vibration operation of the movable plate 31 at the time of scanning and the rotation operation of the polygon mirror 2 by the motor 3 are as follows. Then, N = (k · M · n) (2) (where k is a natural number) Further, since the vertical movement distance in one scan is equal to that where the rotation center is not displaced, Conditions for (1),

[0016]

[Equation 2]

Also, it holds 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 designated by the same reference numerals to avoid redundant description. The information reading apparatus shown in FIG. 2 includes a pressing shaft 44 that presses the vibrating means 4 against the movable plate 31, a stepping motor 42 'that moves the pressing shaft 44 back and forth, and the stepping motor 4
The control means 6 (see FIG. 3) for driving the 2 '.

As shown in FIG. 3, the control means 6 is composed of a pulse generation circuit 61, a switching circuit 62, a motor drive circuit 63, and a current amplification circuit 64.

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

[0021]

[Equation 3]

It is configured to generate a pulse having a period that satisfies the above condition.

The switching circuit 62 advances the motor,
It is a switch for retreating, and its input is connected to the output of the pulse generating circuit 61.

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

The current amplifier circuit 64 is for amplifying the current flowing to the motor, and its input is the motor drive circuit 6.
3 output.

As the vibrating means, especially the second
The configuration is not limited to that of the embodiment, and for example, as shown in FIG.
Alternatively, as shown in FIG. 5, the elliptical cam 41 'is directly connected to the motor 3 for driving the polygon mirror.
May be attached so that one motor 3 can perform two types of operations.

[0027]

As described above, according to the present invention, a constant relationship is established between the distance between the polygon mirror and the recording section, the swing angle of the motor, the spacing between the recording sections of each stage, and the like. Actuating the vibrating means so as to satisfy the specific relational expression, projecting the raster scanning light toward the part where the recording parts are arranged in multiple stages, and reading the information recorded in each recording part without omission. Therefore, information recorded in multiple stages can be leaked without fail, and information can be read reliably and accurately.

[Brief description of drawings]

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

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

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

FIG. 4 is an explanatory diagram showing a modified example of the present invention.

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

[Explanation of symbols]

 1 light source 2 polygon mirror 3 motor 4 vibrating means 5 two-dimensional bar code symbol

Claims (2)

[Claims] 1. A light source from a light source is made incident on a polygon mirror, and each scanning light traveling after being reflected by this polygon mirror is sequentially directed to each recording section in which a plurality of multi-stage recording sections are arranged and information is recorded. An information reading device for reading information recorded in each recording unit by projecting light, causing reflected light returning after being reflected by each recording unit to enter a light receiving unit, and comprising: a motor for rotating and driving the polygon mirror. An information reading apparatus comprising: a vibrating unit that vibrates at a specific frequency and a specific deflection angle with respect to a rotation speed of a polygon mirror. 2. The information reading apparatus according to claim 1, wherein the rotation axis of the polygon mirror is deviated from the output axis of a motor for rotating the polygon mirror by a predetermined angle.