JPH0464186A - Mark reader - Google Patents

Abstract

PURPOSE:To read a mark satisfactorily by switching a state where the mark is read based on scan in all the scanning directions, and a state where it is performed based on a prescribed scanning direction. CONSTITUTION:An operation in which only the scan in prescribed one or plural scanning directions are performed with a beam of light of high output based on the setting of a switching means 33, and an operation in which the scan in all the directions are performed with the beams of light of equal output are selected. When the operation in which only the scan in the prescribed direction with the beam of light of high output is set, a beam emitting means 11 reduces the output in a period when the scan in the scanning direction other than the prescribed scanning direction is performed based on the output of a scanning direction detecting means 31. Thereby, the input of data by mark reading can be performed satisfactorily.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an apparatus for optically reading symbols such as bar codes and characters by scanning them with a beam of light, and more specifically, the present invention relates to an apparatus for optically reading symbols such as bar codes and characters by scanning them with a beam of light. The present invention relates to a symbol reading device that can read symbols regardless of the orientation of the symbols.

<Prior Art> Conventionally, barcode reading devices have been used that scan a symbol surface on which a barcode is formed with a laser beam to read the symbol. In such a device, since the entire barcode must be scanned by the laser beam, the barcode can only be read if the scanning direction of the laser beam and the barcode are in a predetermined positional relationship.

However, in logistics lines, for example, it is difficult to keep the barcodes affixed to objects conveyed by a belt conveyor fixed in a fixed direction, and in supermarket cash registers, it is difficult to keep the barcodes affixed to the same direction. If the direction of the product had to be changed one by one in response to this, work efficiency would be extremely poor. For this reason, fixed barcode readers commonly used for the above applications scan with a laser beam in multiple directions; It is configured to be able to read barcodes that have been read.

Recently, not only fixed barcode reading devices but also handheld devices that house a reading unit containing a laser light source, a light receiving element, etc. in a handy housing have been proposed to have the multidirectional scanning function described above. It is becoming more and more common.

<Problems to be Solved by the Invention> As described above, a device having a multi-directional scanning function is convenient in that it is not necessary to set the positional relationship between the barcode and the reading device accurately, and the barcode reading operation can be easily performed. On the other hand, if multiple barcodes are arranged closely together, there is a risk that the operator may mistakenly read a barcode that is not intended to be read.

Also, if the laser beam scans the barcode diagonally and cannot scan the entire barcode, reading errors may occur. Since the positional relationship between the barcode and the reading device is not set accurately, the possibility of the above-mentioned reading error is greater than in a reading device that can only scan in one direction. This can be fatal, especially if some kind of check is not performed on the read information, so the user may prefer to input data by reading a bar code reliably by unidirectional scanning. The above check is a process that determines whether the reading is accurate or not by detecting, for example, the first and last characters of a barcode, or the number of digits. be.

Thus, while the multidirectional scanning functionality described above is convenient, it can also be a hindrance.

Therefore, the present invention solves the above-mentioned technical problems, and provides two conditions: one in which symbol reading is performed based on all scanning in a plurality of scanning directions, and the other in which symbol reading is performed based on scanning in only a predetermined scanning direction. It is an object of the present invention to provide a symbol reading device which allows data to be inputted by reading the symbol by selecting the symbol.

Means and operation for solving the above problems> A symbol reading device according to claim 1 for achieving the above object includes a beam emitting means for emitting a beam light, and a symbol reading device using the beam light from the beam emitting means. A scanning device for scanning the formed symbol surface in a plurality of mutually different scanning directions, and a light receiving device for receiving reflected light from the symbol surface, and reading the symbol based on scanning in any one of the scanning directions. In a symbol reading device that performs scanning, scanning direction detection means detects the scanning direction, and scanning is performed in one or more predetermined scanning directions selected from the plurality of scanning directions based on the output of the scanning direction detection means. Beam output control that sometimes sets the output of the beam emitting means to a first value, and when scanning in a scanning direction other than the predetermined scanning direction is performed, sets the output to a second value smaller than the first value. and switching means for switching between a state in which the output of the beam output means is controlled by the beam output control means and a state in which the output of the beam output means is not controlled by the beam output control means. It is something that

According to the above configuration, depending on the setting of the switching means, scanning in one or more predetermined scanning directions or with a beam light of high output may be performed, or scanning in all scanning directions may be performed with a beam light of equal output. You can choose the actions. When an operation is set in which only scanning in the predetermined scanning direction is performed using a beam of high output power, the beam emitting means is configured to scan in a scanning direction other than the predetermined scanning direction based on the output of the scanning direction detection means. During the scanning period, the output of the beam emitting means is reduced. When this output is reduced, the light-receiving means cannot obtain enough light to identify the symbol, so the symbol is not read during this scanning.

In this way, the operator can, by setting the switching means,
Depending on the conditions of use, it can be selected whether symbols are read based on scanning in all scanning directions or only on the basis of scanning in a predetermined scanning direction.

In addition, if the second value is set to a value that allows the symbol to be read when the distance between the symbol surface and the reading device is sufficiently short, then when the reading distance is short, the reading operation is performed based on scanning in all scanning directions. When the reading distance is long, the reading operation can be performed based only on scanning in the predetermined scanning direction.

Further, the symbol reading device according to claim 2 includes a beam emitting means for emitting a beam light, and a scanning means for scanning a symbol surface on which a symbol is formed with the beam light from the beam emitting means in a plurality of mutually different scanning directions. and a light-receiving means for receiving eight reflected lights from the symbol surface, in a symbol reading device that reads the symbol based on scanning in any one of the scanning directions, a scanning direction detection for detecting the scanning direction; and based on the output of the scanning direction detection means, when scanning in one or more predetermined scanning directions selected from the plurality of scanning directions is performed, the beam emitting means is pulse-lit at a first frequency, when scanning in a scanning direction other than the predetermined scanning direction is performed, beam output control means for pulse-lighting the beam emitting means at a second frequency different from the first frequency; a filter means for extracting a first frequency component; and a state in which the beam output means is controlled by the beam output control means, and a state in which the beam output means is not controlled by the beam output control means. The apparatus further includes a switching means for switching between fixing the pulse lighting frequency of the emission means to the first frequency.

According to such a configuration, by setting the switching means,
It is possible to select a state in which the pulse lighting frequency of the beam emitting means is switched between the first frequency and the second frequency, or a state in which it is fixed at the first frequency. The output of the light receiving means is given to the filter means and the component of the first frequency is extracted. Therefore, if the symbol is identified based on the output of the filter means, it is determined whether the beam emitting means or the second frequency component is detected. No symbols are read based on scanning when pulsed.

Therefore, scanning in a scanning direction other than the predetermined scanning direction in which the beam emitting means is pulse-lit at the second frequency is substantially ignored, and as a result, the structure according to claim 1 described above Similarly, it is possible to switch between an operation in which symbol reading is performed based on scanning in all scanning directions and an operation in which symbol reading is performed based on scanning in only a predetermined scanning direction.

The symbol reading device according to a third aspect of the present invention is characterized in that it includes a selection means for selecting one or more of the predetermined scanning directions.

With this configuration, the predetermined scanning direction described above can be selected, so a limited scanning direction can be selected depending on the installation state of the device and the symbol formation direction, or according to the operator's preference. Since symbol reading can be performed with , versatility is improved.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 is a block diagram showing the basic configuration of a barcode reading device which is an embodiment of the symbol reading device of the present invention.

A laser beam I! is emitted from a beam emitting means 11 that includes a semiconductor laser light source, its driving circuit, a collimating lens, and the like. 1 is emitted from a scanning means 12 including a polygon mirror or the like through an opening formed in a housing (not shown) toward a barcode 14 formed on a symbol surface 13. The laser beam 11 is scattered by the symbol plane 13, and this scattered light I! The light is received by a light receiving means 15 including two photodiodes and the like. This light receiving means 15
The output of is given to the identification means 17 via the filter means 16 having a pass frequency band centered on a predetermined first frequency, the identification means 17 binarizes the output of the filter means 16, and further The information represented by the barcode 14 is reproduced.

In this embodiment, the beam emitting means 11 has a bar code 14.
Pulse lighting is performed at a first frequency that is sufficiently higher than the spatial frequency of , thereby reducing power consumption, and filtering means 16 extracts the component of the first frequency to reduce the influence of ambient light. to ensure accurate reading.

The scanning means 12 is, for example, a polygon mirror 2, as shown in FIG.
0, plane mirrors 21, 22, and 23 are arranged around the polygon mirror 21 at a predetermined angle with respect to the axis 20b of the polygon mirror 21.
is driven to rotate at a constant angular velocity.

FIG. 3 is a diagram schematically showing how the bar code 14 is scanned by the scanning means 12 described above. polygon mirror 2
As the angle 0 rotates, the angle of incidence of the laser beam on the deflection reflecting surface 20a changes, so that the laser beam from the polygon mirror 20 first enters the plane mirror 21.
The laser beam from this plane mirror 21 forms a scanning line α on the symbol plane 13. When the polygon mirror 20 further rotates, the laser beam from this polygon mirror 20 becomes 2
The laser beam is incident on the second plane mirror 22, and the laser beam from this plane mirror 22 forms a scanning line β on the symbol plane 13. Next, the laser beam from the polygon mirror 20 is incident on the third plane mirror 23 to form a scanning line γ on the symbol plane 13. In this way, the laser beam
3, scanning lines α, β, and γ in mutually different directions are formed.

If any one of the scanning lines α, β, and γ crosses the entire barcode 14, the barcode 14 can be read based on the output of the light receiving means 15 at this time. In the following description, the above scanning line α will be used.

The scanning of the barcode 14 by the laser beam 11 that forms β and γ, respectively, is called "α direction scanning" and "β
These are referred to as ``direction scanning'', ``γ direction scanning J, etc.

On the optical path from the scanning means 12 to the symbol plane 13, a first
As shown in the figure, a scanning direction detection means 31 for detecting the above three scanning directions is arranged, and its detection output is given to a beam output control means 32 that controls the output of the beam emission means 11. ing. In this embodiment, the beam output control means 32 pulse-drives the beam output means 11 at the first frequency, and controls the duty ratio of turning on/off the beam output means 11. The average output of the laser beam fl is controlled.

The beam output control means 32 includes a switching means 33 for switching between multi-directional scanning, which performs scanning in all three directions, and unidirectional scanning, which performs scanning in one direction arbitrarily selected from the back of the three directions. a selection means 3 connected to the unit and further for selecting the direction in which scanning is performed during the one-way scanning;
4 are connected.

FIG. 4 is a conceptual diagram showing the basic configuration of the scanning direction detection means 31. For example, an opening 40 for emitting the laser beam 21 is formed in the casing 35 in which the beam emitting means 11 and the scanning means 12 are housed. Three light receiving elements 41, 42, 43 are fixed to the inner wall of the body 35,
The scanning direction detecting means 31 is also configured. Each of the light receiving elements 41, 42, 43 corresponds to the above scanning line αβ, γ, respectively.
When the above-mentioned α direction scan, β direction scan, or γ direction scan is performed, the laser beam 11 at the end of the scan is received.

With the above-described configuration, when the direction of the barcode to be read is not constant, as in the case of a supermarket cash register, for example, multi-directional scanning is selected by setting the switching means 33. In this state,
Symbol plane 13 shows the above scanning lines α, β, and γ, all of which are laser beams I with the same average output! 1, the barcode 14 can be identified based on the output of the light receiving means 15 when which scanning line crosses the entire barcode 14. In this case, since it is not necessary to strictly set the positional relationship between the barcode 14 and the device, the workability of data input by barcode reading is improved.

On the other hand, if multiple barcodes are present side by side, for example, performing multidirectional scanning as described above may result in a barcode being read that the operator did not intend to read, so it is not recommended. do not have. In such a case,
The operator may select α direction scanning, β direction scanning, or γ direction scanning using the selection means 34 and set unidirectional scanning using the switching means 33. In response, the beam output control means 32 increases the average output of the beam output means 11 (to the first value) when scanning in the selected direction, and increases the average output of the beam output means 11 when scanning in the other direction. Means 11
(second value).

FIG. 5 is a timing chart for explaining the operation when unidirectional scanning is performed by selecting α direction scanning in the selection means 34. Figure 5(a).

(b) and (C) are the photodetector elements 41.4 in Fig. 4, respectively.
FIG. 5(d) shows the operation of the beam emitting means 11. α direction scanning, β direction scanning, γ
Directional scanning is performed cyclically, so...→α→β→γ
Scanning lines are formed in the order of →α→....

At time t], when the laser beam 11 from the pulsed beam emitting means 11 is detected by the light receiving element 43 and scanning in the γ direction is completed, the laser beam I! from the light receiving element 41 is then detected. During the period Tα until detecting l, the beam output control means 32 adjusts the lighting time Δ and the light-off time Δ. Increasing the ratio to 1 increases the average power of the laser beam All. As a result, the α direction scanning performed during the period Tα is performed by the laser beam fl having a large average output.

At time t2, when the light receiving element 41 detects the laser beam 11 and finishes scanning in the α direction, the beam output control means 32 sets the lighting time Δ. N lights out time Δ. □, which reduces the average power of the laser beam AI. In this way, the β
Directional scanning will be performed by a low power laser beam f+. Also, during the period Tγ after the light-receiving element 42 detects the laser beam fl until the light-receiving element 43 detects the laser beam 11, the low-power laser beam I
! γ-direction scanning is performed by l.

In this way, while only scanning in the α direction is performed using the laser beam 11 with a large average output power, the light receiving means 15 can be used to detect bar codes in a period in which each scan in the β and γ directions is performed. It is not possible to obtain a large output, and as a result, barcode reading is performed based only on scanning in the α direction.

As described above, according to this embodiment, a multi-directional scanning operation is performed in which barcodes are read based on scanning in three directions;
The operator can select a unidirectional scanning operation in which reading is performed based on scanning in two directions. Therefore, in multi-directional scanning, for example, because multiple barcodes are located close to each other,
If there is a risk of accidentally reading a nearby barcode, which would actually reduce the efficiency of the data input operation, it is possible to switch to unidirectional scanning to perform data input more efficiently. In this way, the operator can select between unidirectional scanning and multidirectional scanning according to the conditions of use, thereby greatly improving the workability of data input by barcode reading.

In this embodiment, the scanning direction during unidirectional scanning can be selected by the selection means 34 in order to improve versatility in response to various usage conditions. In other words, in the case of a barcode reader that is fixedly placed above a belt conveyor, for example, the barcode attached to the object being conveyed on the conveyor is formed in the direction in which the barcode is formed, regardless of the installation direction of the barcode reader. can correspond to In addition, in the case of a handheld barcode reading device, if the scanning direction can be appropriately selected depending on the operator's dominant hand or personal preference, the reading operation can be performed more efficiently.

Furthermore, in this embodiment, when the unidirectional scanning operation is set by the switching means 33, scanning is performed in the selected scanning direction with a high-power laser beam, and scanning in the remaining scanning directions is performed with a low-power laser beam. Since this is done using a beam, by selecting the value of each output appropriately, multi-directional scanning can be performed when the distance between the barcode and the device is short, or when the distance between the barcode and the device is long. It is also possible to perform reading by unidirectional scanning. In this way, if the barcode is far away, it is possible to prevent the operator from reading a barcode that is not intended to be read, and also to ensure that the positional relationship between the barcode and the device is strictly controlled when reading nearby barcodes. No settings required (can be done with good workability).

In this embodiment, when the unidirectional scanning operation is selected, the output of the laser beam fl may be completely stopped during a period in which scanning other than the α direction scanning is performed, for example. However, in this case, since the configuration shown in FIG. 4 cannot detect the scanning direction, for example, the configuration shown in FIG. 6 is applied instead.

That is, the motor 2 that rotationally drives the polygon mirror 20
A permanent magnet piece 51 is fixed to the drive shaft 24a of the permanent magnet piece 51, and a plurality of coils 52 are arranged near the rotation orbit of the permanent magnet piece 51, and the output of the coil 52 is connected to the angle detection circuit 5.
3 is given.

With this configuration, since the rotational position of the polygon mirror 20 can be detected, the laser beam I! from the beam emitting means 11! It is possible to determine which plane mirror 21 to 23 the light beam 1 is incident on, and therefore each scan in the α direction, β direction, and γ direction can be detected. Therefore, the output of the angle detection circuit 53 is applied to the beam output control means 32 shown in FIG.
What is necessary is to stop the generation of the laser beam fl from 1.

Next, other embodiments of the present invention will be described. In the above embodiment, during the unidirectional scanning operation, the average output of the laser beam 11 is reduced (or stopped) when scanning in a non-selected direction, or in this embodiment, the average output of the laser beam 11 is not reduced. Then, the frequency of the pulse lighting is switched to a second frequency different from the first frequency.

That is, for example, when α direction scanning is selected by the selection means 34 and unidirectional scanning operation is set by the switching means 33, the beam output control means 32 selects the scanning direction detection means 31.
Based on the output of
The first frequency is a frequency in the pass frequency band of No. 6, and the beam emitting means 11 is pulse-lit at a second frequency, which is a frequency outside the pass frequency band, during the period when β direction scanning and γ direction scanning are performed. do.

As a result, when scanning in the α direction, the output of the light receiving means l is blocked by the filter means 16, so that the identification means 1 is outside the plate.
7 identifies barcodes based only on scanning in the α direction. In this way, substantially unidirectional scanning is achieved.

Note that the present invention is not limited to the above-mentioned embodiments. For example, in the above-described embodiments, the case where the multi-directional scanning operation and the unidirectional scanning operation can be switched is taken as an example. It may also be possible to switch between the operation of performing this operation and the operation of selectively performing only scanning in two or more directions selected from among the IO force directions. In this way, reading performance can be improved by enabling scanning in, for example, two or three adjacent directions.

Furthermore, although the above-mentioned embodiment has been explained by taking a barcode reading device as an example, the present invention is applicable to a symbol reading device that reads a symbol by scanning the symbol with a beam of light.
It can be easily applied to, for example, an optical character reading device. Various other design changes may be made without departing from the gist of the present invention.

<Effects of the Invention> As described above, according to the symbol reading device of the present invention, symbols can be read based on scanning in all scanning directions, and symbols can be read based on scanning only in a predetermined scanning direction. The state to be performed can be selected by setting the switching means. Therefore, when reading by scanning in all scanning directions, there is a risk that symbols that are not intended to be read may be read, such as when multiple symbols exist within the reading field of the device. By switching to a state in which reading is performed only based on the above-described predetermined scanning direction,
Can read symbols well.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a barcode reading device according to an embodiment of the symbol reading device of the present invention, FIG. 2 is a perspective view showing a simplified configuration of the scanning means 12, and FIG. 4 is a conceptual diagram showing the structure of the scanning direction detecting means 31, FIG. 5 is a timing chart for explaining the operation, and FIG. 6 is scanning direction detection. It is a perspective view which shows another example of a structure of a means in a simplified manner. 16... Filter means, 31... Scanning direction detection means, 32... Beam output control means, 33... Switching means, 34... Selection means

Claims (1)

[Scope of Claims] 1. A beam emitting means for emitting a beam light, a scanning means for scanning a symbol surface on which a symbol is formed with the beam light from the beam emitting means in a plurality of mutually different scanning directions, and the above-mentioned symbol. A symbol reading device having a light receiving means for receiving reflected light from a surface and reading the symbol based on scanning in one of the scanning directions, a scanning direction detection means for detecting the scanning direction; Based on the output of the direction detecting means, when scanning is performed in one or more predetermined scanning directions selected from the plurality of scanning directions, the output of the beam emitting means is set as the first value, and when scanning is performed in one or more predetermined scanning directions selected from the plurality of scanning directions, beam output control means for setting the output to a second value smaller than the first value when scanning in the scanning direction is performed; and a state in which the output of the beam emitting means is controlled by the beam output control means. and a switching means for switching between a state in which the output of the beam emitting means is not controlled by the beam output control means. 2. A beam emitting means for emitting a beam of light; a scanning means for scanning a symbol surface on which a symbol is formed with the beam light from the beam emitting means in a plurality of mutually different scanning directions; A symbol reading device having a light receiving means for receiving light and reading the symbol based on scanning in one of the scanning directions, a scanning direction detection means for detecting the scanning direction, and an output of the scanning direction detection means. Based on this, when scanning in one or more predetermined scanning directions selected from the plurality of scanning directions is performed, the beam emitting means is pulse-lit at a first frequency, and scanning in scanning directions other than the predetermined scanning directions is performed. When this is carried out, a beam output control means for pulse-lighting the beam emitting means at a second frequency different from the first frequency, and a filter means for extracting a component of the first frequency from the output of the light receiving means. and a state in which the beam output means is controlled by the beam output control means, and a pulse lighting frequency of the beam output means is changed to the first state in which the beam output means is not controlled by the beam output control means. 1. A symbol reading device comprising: switching means for switching between a state in which the frequency is fixed at a frequency of 3. The symbol reading device according to claim 1 or 2, further comprising selection means for selecting one or more of the predetermined scanning directions.