Patent Publication Number: US-6211986-B1

Title: Optical reading apparatus having optical scanner for scanning information on objects

Description:
This is a Divisional of prior application Ser. No. 08/932,172 joled on Sep. 17, 1997 now U.S. Pat. No. 5,815,300, which is a continuing application of application Ser. No. 08/274,348, filed on Jul. 13, 1994, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an optical reading apparatus having an optical scanner for scanning information on objects, and more particularly to an optical reading apparatus having a stationary-type optical scanner for scanning bar codes on articles of trade, which apparatus is used in a POS (Point of Sales) system provided in a store. 
     2. Description of the Related Art 
     Conventional optical reading apparatuses, such as bar code reading apparatus used in the POS system, are classified, based on setting forms of the optical scanners and directions in which scanning light beams travels from the optical scanner, into the following three types. 
     The first type is referred to as a horizontal setting form and beam upward emission type. This type of bar code reading apparatus is shown, for example, in FIG.  1 . Referring to FIG. 1, a scanner unit  20  is horizontally set on the surface of a check-out counter  21 . Scanning light  23  travels obliquely upward from a window  22  on the upper surface of the scanner unit  20 . An operator takes out each article from an article basket  24  and moves it over the scanner unit  20  in a direction shown by an arrow  25 . When an article is moved over the scanner unit  20 , a bar code on the article is optically scanned by the scanning light  23  so as to be read. After the bar codes of all the articles have been read, the article basket  24  which is empty is moved over the scanner unit  20  as shown by an arrow  26 . 
     The second type is referred to as a vertical setting form and beam frontward emission type. This type of bar code reading apparatus is shown, for example, in FIG.  2 . Referring to FIG. 2, a scanner unit  30  stands on the check-out counter  21  so that a window  31  of the scanner unit  30  is vertical to the surface of the check-out counter  21 . Scanning light  32  travels frontward (toward an operator) from the window  31 . The operator takes out each article from the article basket  24  and moves each article, in a direction shown by an arrow  33 , while positioning it in such a way that a bar code thereon faces the scanner unit  30 . When each article passes through an area in front of the scanner unit  30 , the bar code thereon is read. After the bar codes of all articles have been read, the article basket  24  which is empty is moved so as to slide on the check-out counter  21  as shown by an arrow  34 . 
     The third type is referred to as an overhead setting form and beam downward emission type. This type of bar code reading apparatus is shown, for example, in FIG.  3 . Referring to FIG. 3, a scanner unit  40  is supported by a post  41  as to be located above the check-out counter  21 . A window from which scanning light  43  travels faces the surface of the check-out counter  21 . That is, the scanning light  43  travels downward from the window  42  of the scanner unit  40 . The operator takes out each article from the article basket  24  and moves each article, in a direction shown by an arrow  44 , while positioning it in such a way that a bar code thereon is directed upward to face the scanner unit  40 . After the bar codes of all the articles have been read, the article basket  24  which is empty is moved so as to slide on the check-out counter  21  as shown by an arrow  45 . 
     In the first type of conventional bar code reading apparatus as shown in FIG. 1, there is no obstacle above the scanner unit  20 , so that the operator can move articles more quickly than in the cases of the second and third types of conventional bar code reading apparatuses as shown in FIGS.2 and 3. In addition, since the scanning light  23  travels upward from the article basket  24 , the scanning light  23  does not enter the article basket  24 , thus preventing articles from being mistakenly read. 
     In the second and third types of conventional bar code reading apparatuses as shown in FIGS. 2 and 3, the article basket  24  can be moved so as to slide on the check-put counter  21  without hitting the article basket  24  on the scanner unit  30  or  40 . 
     In the first and second types of conventional bar code reading apparatuses as shown in FIGS. 1 and 2, handling of a boat-shaped article as shown in FIG. 4 is inferior. A boat-shaped article  12  as shown in FIG. 4 is formed of a dish  10  in which food, such as raw fish or meat, is put and a wrapping sheet  11  by which the dish  10  is wrapped. A bar code label  13  on which a bar code is formed is attached to the wrapping sheet  11 . When the boat-shaped article  12  is scanned by the first type of conventional bar code reading apparatus, the boat-shaped article  12  must be upside down so that the bar code label  13  faces the scanner unit  20 . Thus, there is a case where the food in the dish  10  is deformed and/or food juice leaks out of the dish  10 . When the boat-shaped article  12  is scanned by the second type of conventional bar code reading apparatus, the boat-shaped article  12  must be inclined so that the bar code label  13  faces the scanner unit  30 . Thus, in this case, the same problem as in the case of the first type of conventional bar code reading apparatus occurs. 
     In addition, in the third type of conventional bar code reading apparatus, if the article basket  24  is mistakenly moved under the scanner unit  40 , the scanning light  43  enters the article basket  24 . In this case, bar codes or other articles in the article basket  24  are mistakenly read. 
     SUMMARY OF THE PRESENT INVENTION 
     Accordingly, a general object of the present invention is to provide a novel and useful optical reading apparatus in which the disadvantages of the aforementioned prior art are eliminated. 
     A more specific object of the present invention is to provide an optical reading apparatus in which the handling of articles to be scanned thereby can be quickly carried out. 
     Another object of the present invention is to provide an optical reading apparatus in which, after all articles in an article basket have been optically scanned, the handling of the article basket which is empty is superior. 
     Another object of the present invention is to provide an optical reading apparatus in which information on articles in an article basket is prevented from being mistakenly read thereby. 
     The above objects of the present invention are achieved by an optical reading apparatus comprising: an optical scanning unit for emitting upward a scanning light beam to be used to optically read information on an article; and a supporting mechanism for supporting the optical scanning unit so that the optical scanning unit is maintained in a space over a surface of a counter in a state where a distance between the optical scanning unit and the surface of the counter is a predetermined length. 
     Above objects of the present invention are also achieved by an optical reading apparatus comprising: an optical scanning unit for emitting upward a main-scanning light beam to be used to optically read information on an article, and for emitting a sub-scanning light beam in a direction different from a direction in which the main-scanning light beam travels, the sub-scanning light beam being used to optically read information on an article; and a supporting mechanism for supporting the optical scanning unit so that the optical scanning unit is maintained in a space over a surface of a counter in a state where a distance between the optical scanning unit and the surface of the counter is a predetermined length. 
     According to the present invention, since the information on the article can be read by the scanning line while the article is being moved over the optical scanning unit, the handling of the article to be scanned can be quickly carried out. In addition, after all articles in an article basket (the container) have been optically scanned, the article basket which is empty can be moved under the optical scanning unit so as to be slide on the counter. Thus, the handling of the article basket (the container) is superior. Further, since the scanning light beam travels upward from the optical scanning unit, information on articles in the article basket (the container) is prevented from being mistakenly read thereby. 
     Another object of the present invention is provide an optical reading apparatus which can be set on a counter in various setting forms. 
     The object of the present invention is achieved by an optical reading apparatus comprising: a scanning light beam generating system for generating a scanning light beam used to optically read information on an article; and an optical system for changing a readable region in which the information on the article can be read by the scanning light beam generated by the scanning light beam generating system. 
     According to the present invention, since the readable position can be changed, the optical scanning apparatus can be set on the counter in various setting forms in accordance with readable positions. As a result, in a case where a plurality of types of optical scanning apparatuses having different readable positions are provided, the production cost of each type of optical scanning apparatus can be decreased. 
    
    
     Additional objects, features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings. 
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view illustrating an example of a first type of conventional bar code reading apparatus. 
     FIG. 2 is a perspective view illustrating an example of a second type of conventional bar code reading apparatus. 
     FIG. 3 is a perspective view illustrating an example of a third type of conventional bar code reading apparatus. 
     FIG. 4 is a perspective view illustrating a boat-shaped article. 
     FIG. 5 is perspective view illustrating a bar code reading apparatus according to a first embodiment of the present invention. 
     FIG. 6 is a diagram illustrating the structure of an optical system in a scanner body of the bar code reading apparatus shown in FIG.  5 . 
     FIG. 7 is a perspective view illustrating a bar code reading apparatus according to a second embodiment of the present invention. 
     FIG. 8 is a diagram illustrating the structure of an optical system in a scanner unit of the bar code reading apparatus shown in FIG. 7 
     FIG. 9 is a perspective view illustrating a polygonal mirror used in the optical system shown in FIG.  8 . 
     FIG. 10 is a digram illustrating a first modification of the optical system shown in FIG.  8 . 
     FIG. 11 is a diagram illustrating the operation of a transmission type hologram in the optical system shown in FIG.  10 . 
     FIG. 12 is a diagram illustrating a second modification of the optical system shown in FIG.  8 . 
     FIG. 13 is a diagram illustrating the operation of a transmission type hologram in the optical system shown in FIG.  12 . 
     FIG. 14 is a perspective view illustrating a bar code reading apparatus according to a third embodiment of the present invention. 
     FIG. 15 is a diagram illustrating an optical guide plate provided in the bar code reading apparatus shown in FIG.  14 . 
     FIG. 16 is a perspective view illustrating a bar cord reading apparatus according to a fourth embodiment of the present invention. 
     FIG. 17 is a diagram illustrating the structure of an optical system in a scanner unit shown in FIG.  16 . 
     FIG. 18A is a diagram illustrating the optical system shown in FIG. 17 in a normal state. 
     FIG. 18B is a diagram illustrating the optical system shown in FIG. 17 is a state where boat-shaped articles are handled. 
     FIG. 19 is a perspective view illustrating a bar code reading apparatus according to a fifth embodiment of the present invention. 
     FIG. 20 is a table illustrating evaluation of bar code recording apparatuses according to the present invention in comparison with conventional bar code recording apparatuses. 
     FIG. 21 is a perspective view illustrating a bar code reading apparatus according to another embodiment of the present invention. 
     FIG. 22A is a diagram illustrating the bar code reading apparatus, shown in FIG. 20, used in a horizontal setting form. 
     FIG. 22B is a diagram illustrating the bar code reading apparatus, shown in FIG. 20, used in a vertical setting form. 
     FIG. 23 is a perspective view illustrating a bar code reading apparatus according to another embodiment of the present invention. 
     FIG. 24A is a diagram illustrating the bar code reading apparatus, shown in FIG. 22, used in the vertical setting form. 
     FIG. 24B is a diagram illustrating the bar code reading apparatus, shown in FIG. 22, used in an overhead setting form. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now given, with reference to FIGS. 5 and 6, of a first embodiment of the present invention. 
     Referring to FIG. 5, a bar code reading apparatus  50  has a scanner unit  51 . The scanner unit  51  is supported by posts  52  and  53  so as to be located at a height H above the check-out counter  21 . A lower surface of the scanner unit  51  is at a distance (a) from a surface  21   a  of the check-out counter  21 . The distance (a) between the lower surface of the scanner unit  51  and the surface  21   a  of the check-out counter  21  is slightly greater than a height (b) of an article basket  24 . That is, a space  55  through which the article basket  24  can pass is formed between the scanner body  51  and the check-out counter  21 . The posts  52  and  53  supporting the scanner unit  51  are located on a side of the check-out counter  21  opposite to a side on which an operator stands so as to be out of the operator&#39;s way during check-cut operations. The scanner unit  51  has a reading window  54  formed on an upper surface  51   a  thereof. 
     An optical system  59  as shown in FIG. 6 is mounted inside the scanner unit  51 . Referring to FIG. 6, the optical system has a laser source  60 , a polygonal mirror  61  for moving a scanning laser beam, reflection mirrors  62 ,  63  and  64 , a bottom surface mirror  65 , a detector  66 , a reflection mirror  71  and a concave mirror  72  having an incident area  72   a . The reflection mirrors  62 ,  63  and  64  and the bottom surface mirror  65  are used to divide a scanning laser beam. 
     A laser beam  70  emitted from the laser source  60  travels to the polygonal mirror  61  via the reflection mirror  71  and the incident area  72   a  of the concave mirror  72 . The laser beam  70  reflected by each surface of the polygonal mirror  61  is swung by the rotation of the polygonal mirror  61  in a direction shown by an arrow  73  so that a scanning laser beam  74  is made. The scanning laser beam  74  scans the reflection mirrors  62 ,  63  and  64  in this order, so that the scanning laser beam  74  is divided into scanning laser beams  76 ,  77  and  78  by the reflection mirrors  62 ,  63  and  64 . The respective scanning laser beams  76 ,  77  and  78  are reflected by the bottom surface mirror  65 , and reflected scanning laser beams  79 ,  80  and  81  travel toward the scanning window  54 . The scanning laser beams  79 ,  80  and  81  are then emitted through the scanning window  54  and travel obliquely upward from the scanning window  54  as shown in FIG.  5 . The scanning laser beams  79 ,  80  and  81  move in different directions so that a star-shaped scanning line pattern  82  having three lines is formed in a space above the scanner body  51 . 
     When an article is brought into the space in which the scanning line pattern  82  is formed so that the scanning laser beams  79 ,  80  and  81  are projected onto a surface of the article on which a bar code is formed, the scanning laser beams  79 ,  80  and are projected scattered by the surface having the bar code. A part of the scattered beam including information of the bar code enters the scanner unit  51  through the scanning window  54  and then returns along the same optical path as that of the laser beam in a direction opposite to that in which the laser beams travel. The returning beam is focused on the detector  66  by the concave mirror  73 . Based on a detecting signal output from the detector  66 , information corresponding to the bar code on the article is generated. That is, the bar code is read. 
     In the bar code reading apparatus shown in FIG. 5, first, an article is taken out from the article basket  24 . Next, the article, which is positioned in such a way that the surface having the bar code is facing downward, is moved over the scanner unit  51  as shown by an arrow  90 . The article is then brought into a receiving basket (not shown). A series of the above operations is repeated in the check-out operation. While each article is being moved, a bar code formed on each article is read by the bar code reading apparatus. 
     In the bar code reading apparatus shown in FIG. 5, there is no obstacle above the scanner unit  51 , so that the operator can carry out the check-out operation without the inconvenience of any obstacles. Thus, the operator can quickly move articles from the article basket  24  to the receiving basket. 
     The thickness (t) of the scanner unit  51  is slight, so that the distance (c) between the upper surface  51   a  of the scanner unit  51  and the surface  21  of the check-out counter  21  is slightly greater than the height (b) of the article basket  24 . Thus, the operator can move each article over the scanner unit  51  without deterioration of the working efficiency. In addition, the scanning laser beams  79 ,  80  and  81  are emitted upward from a position higher than the article basket  24 , so that bar codes on articles in the article basket  24  are not mistakenly scanned by the scanning laser beams  79 ,  80  and  81 . The operator can slide the article basket  24  which is empty on the surface  21   a  of the check-out counter  21  under the scanner unit  51 , as shown by an arrow  91 . The article basket  24  is thus moved under the scanner unit  51  to a position at which the article basket  24  which is empty can be used as a receiving basket. 
     A description will now be given, with reference to FIGS. 7,  8  and  9 , of a second embodiment of the present invention. In FIGS. 7 and 8, those parts which are the same as those shown in FIGS. 5 and 6 are given the same reference numbers. 
     Referring to FIG. 7, a bar code reading apparatus  100  has a scanner unit  51 A supported by the posts  52  and  53  in the same manner as that shown in FIG.  5 . The scanner unit  51 A has the window  54  formed on an upper surface  51 A a  thereof and a sub-window  105 . The sub-window  105  is formed so as to be extend from a corner portion  103 , at which front and side surfaces  101  and  102  of the scanner unit  51 A are joined to each other, to a lower surface  104 . 
     An optical system  59 A shown in FIG. 8 is mounted in the scanner unit  51 A. Referring to FIG. 8, the optical system  59 A has elements the same as the optical system  59  shown in FIG. 6, except that a polygonal mirror  106  and a space  107  between the reflection mirror  64  and the bottom surface mirror  65  are additionally provided. The polygonal mirror  106  is a pentagonal prism as shown in FIG. 9 . Referring to FIG. 9, the polygonal mirror  106  has five surfaces  106   −1 - 106   5  each of which corresponds to one of surfaces of the pentagonal prism. A surface  106   −1  which is one of the five surfaces  106   −1 - 106   −5  is divided into two surfaces  106   −1a  and  106   −1b . The surface  106   −1a  has the same inclination as the other surfaces  106   −2 - 106   −5 , and the surface  106   −1a  is inclined so that an angle between the surfaces  106   −1a  and  106   −1b  is maintained at θ. The scanning laser beam  74  generated by reflection on the surfaces  106   −2 - 106   −5  scans all three of the reflection mirrors  62 ,  63  and  64 . The scanning laser beam  74  generated by reflection on the surface  106   −1a  only scans two out of the three reflection mirrors  62 ,  63  and  64 , that is, the mirrors  62  and  63 . A scanning laser beam  74   a  generated by reflection on the surface  106   −1b  travels obliquely downward from a plane on which the scanning laser beam  74  travels to the space  107  between the reflection mirror  64  and the bottom surface mirror  65 . The scanning laser beam  74   a  passes through the space  107  and travels to the sub-window  105  of the scanner unit  51 . As a result, a scanning beam  108  (corresponding to the scanning laser beam  74   a ) travels, as a sub-scanning laser beam, obliquely downward from the sub-window  105  as shown in FIG.  7 . The scanning beam  108  forms a scanning line pattern  109  at a predetermined position above the surface  21   a  of the check-out counter  21 . 
     The scanning laser beam  74  from the surfaces  106   −2 - 106   −5  and  106   −1a  of the polygonal mirror  106  is reflected by the bottom surface mirror  65 , so that the divided scanning laser beams  79 ,  80  and  81  travel, as main scanning laser beams, obliquely upward from the window  54 , in the same manner as in the first embodiment. That is, the laser scanning line pattern  82  is formed in a space above the scanner unit  51 . 
     In the bar code reading apparatus  100  shown in FIG. 7, the operator takes out each article from the article basket  24  and moves it over the scanner unit  51  as shown by the arrow  90  so that a bar code on each article is scanned by the scanning laser beams  79 ,  80  and  81 . As a result, the bar code on each article is optically read. In addition, the operator moves a boat-shaped article as shown in FIG. 4 so that the boat-shaped article passes under the scanner unit  51  as shown by an arrow  111 . In this case, the boat-shaped article is maintained in such a position that the dish  10  is facing downward and the bar code label  13  is facing upward. Thus, the bar code on the boat-shaped article is scanned by the scanning laser beam  108  under a condition in which the food in the dish  10  is not deformed and/or food juice does not leak out of the dish  10 . 
     The scanning line pattern  109  based on the scanning laser beam  108  traveling downward from the sub-window  105  has a small size, so that there is almost no case where bar codes on articles in the article basket  24  are mistakenly read by the scanning laser beam  108 . The operator slides the article basket  24  which is empty on the surface  21   a  of the check-out counter  21  under the scanner unit  51  as shown by the arrow  91 . 
     A description will now be given, with reference to FIGS. 10-13, of modifications of the optical system shown in FIG.  8 . IN FIGS. 10-13, those parts which are the same as those shown in FIGS. 6 and 8 are given the same reference numbers, and the explanation of those parts will be omitted. 
     An optical system  59 B according to a first modification is shown in FIG. 10 and 11. Referring to FIGS. 10 and 11, the optical system  59 B is provided with the normal polygonal mirror  61  used in the first embodiment and a transmission hologram plate  115  which is located between the reflection mirror  64  and the bottom surface mirror  65 . The transmission hologram plate  115  is located so that the Bragg angle of the hologram is equal to an incident angle at which the scanning laser beam  78  from the reflection mirror  64  is incident to the transmission hologram plate  115 . Thus, the scanning laser beam  78  is diffracted by the transmission hologram plate  115 , so that a diffraction scanning laser beam  116  is emitted from a transmission hologram plate  115  as shown in FIG.  11 . The diffraction scanning laser beam  78  from the transmission hologram plate  115  passes through the space  107  between the reflection mirror  64  and the bottom surface mirror  65  and travels to the sub-window  105 . The diffraction scanning laser beam  116  travels, as the scanning laser beam  108 , obliquely downward from the sub-window  105 . 
     An optical system  59 C according to a second modification is shown in FIGS.12 and 13. Referring to FIGS. 12 and 13, a reflection hologram plate  117  is substituted for the transmission hologram plate  116 . The reflection hologram plate  117  is built inside the bottom surface mirror  65 . An incident angle β of the scanning laser beam  78  from the reflection mirror  64  with respect to the reflection hologram plate  117  greatly differ from the Bragg angle of the reflection hologram plate  117 . Thus, the scanning laser beam  78  from the reflection mirror  64  passes through the reflection hologram plate  117 , and a passing laser beam  118  travels from the reflection hologram plate  117  toward the sub-window  105  of the scanner unit  51  shown in FIG.  7 . The passing laser beam  118  travels, as the scanning laser beam  108 , obliquely downward from the sub-window  105 . 
     A description will now be given, with reference to FIGS. 14 and 15 of a third embodiment of the present invention. In FIG. 14, those parts which are the same as those shown in FIG. 5 are given the same reference numbers. 
     Referring to FIG. 14, a bar code reading apparatus  120  has a scanner unit  51 B supported by the posts  52  and  53 . The scanner unit  51 B is formed of a main body  51 B a  and an optical guide unit  121 . The optical guide unit  121  extends upward from a side of the main body  51 B a  supported by the posts  52  and  53 . The optical guide unit  121  has side wall surfaces  121   a  and  121   b  opposite to each other and a top surface  121   c . A laser beam is alternately reflected by the side wall surfaces  121   a  and  121   b  so that the laser beam is directed from the bottom to the top surface  121   c . The optical guide unit  121  has a surface located at an upper portion thereof which functions as a window  121   d  through which the laser beam reflected by the top surface  121   c  travels obliquely downward from the top surface  121   c . Either the optical system  59 A shown in FIG. 8, the optical system  59 B shown in FIG. 10 or the optical system  59 C shown in FIG. 12 is mounted in the main body  51 B a.    
     In FIG. 14, the scanning laser beams  79 ,  80  and  81  travel obliquely upward from the window  54  so that the scanning line pattern  82  is formed in the space above the scanner unit  51 B. In addition, for example, in a case where the optical system  59 A shown in FIG. 8 is mounted in the main body  51 B a , the scanning laser beam  74   a  passes through the space  107  between the reflection mirror  64  and the bottom surface mirror  65  and is directed to the optical guide unit  121 . The scanning laser beam directed to the optical guide unit  121  is propagated through the optical guide unit  121  from the bottom toward the top surface  121   c  as a beam  122  shown in FIG.  15 . The laser beam reflected by the top surface  121   c  travels obliquely downward therefrom and passes through the window  121   d . The scanning laser beam  123  emitted from the window  121   d  of the optical guide unit  121  travels obliquely downward so that a scanning line pattern  124  is formed above the scanner unit  51 B as shown in FIG.  14 . 
     In the bar code reading apparatus  120  as shown in FIG. 14, the operator moves a normally shaped article over the scanner unit  51 B as shown by the arrow  90  so that an bar code on the normally shaped article is scanned by the scanning laser beams  79 ,  80  and  81 . In the case of a boat-shaped article, the operator moves the boat-shaped article over the scanner unit  51 B so that the dish  10  is facing downward and the bar code label is facing upward. In this case, the boat-shaped article is moved along a path  131  near the optical guide unit  121  so that a bar code formed on the bar code label  13  of the boat-article is scanned by the scanning laser beam  123 . 
     The article basket  24  which is empty is moved so as to slide on the surface  21   a  of the check-out counter  21  under the scanner unit  51 B as shown by the arrow  91 . 
     In this embodiment, furthermore, since, in addition to normally shaped articles, the boat-shaped article as shown in FIG. 4 can also be moved over the scanner unit  51  to scan a bar code thereon, the check-out operation can be performed more efficiently than in the cases of the first and second embodiments. 
     A description will now be given, with reference to FIGS. 16,  17 ,  18 A and  18 B, of a fourth embodiment of the present invention. In FIG. 16 and 17, those parts which are the same as those shown in FIGS. 7 and 10 are given the same reference numbers, and the explanation of those parts will be omitted. 
     Referring to FIG. 16, a bar code reading apparatus  140  has a scanner unit  51 A a  supported by the posts  52  and  53 . The scanner unit  51 A a  has a selecting operation nob  141  located on the front surface of the scanner unit  51 A a . An optical system  59 B a  as shown in FIG. 17 is mounted in the scanner unit  51 A a . Referring to FIG. 17, the transmission hologram plate  115  is fixed on a tip end of a rod  142 , and is supported so as to be rotatable within a predetermined angle range. The operation nob  141  is fixed on an opposite end of the rod  142 . 
     In a normal case, the operation nob  141  is rotated in a direction shown by an arrow  143  (the clockwise direction) , so that the transmission hologram plate  115  is maintained in a state as shown in FIG.  18 A. In this state, the incident angle τ of the laser beam  78  from the reflection mirror  64  with respect to the transmission hologram plate  115  greatly differs from the Bragg angle of the transmission hologram plate  115 . Thus, the laser beam  78  passes through the transmission hologram plate  115 , and is then reflected by the bottom surface mirror  65 . The reflected beam  145  travels upward from the bottom surface mirror  65 . As a result, the scanning laser beams  79 ,  80  and  81  based on the reflected beam  145  are emitted from the window  54  on the upper surface of the scanner unit  51 A a  and travel obliquely upward therefrom so that scanning line pattern  82  is formed. When articles are moved over the scanner unit  51 A a , bar codes thereon are read. In this case, no laser beam is emitted from the window  105 . Thus, bar codes on articles in the article basket  24  are not read at all. 
     In the case of handling boat-shaped articles, the operation nob  141  is rotated in a direction shown by an arrow  144  (the counterclockwise direction), so that the transmission hologram plate  115  is maintained in a state as shown in FIG.  18 B. In this state, the incident angle α of the laser beam  78  from the reflection mirror  64  with respect to the transmission hologram plate  115  is equal to the Bragg angle of the transmission hologram plate  115 . Thus, the laser beam  78  is diffracted by the transmission hologram plate  115 . The diffracted laser beam  116  travels obliquely downward from the transmission hologram plate  115 . The diffracted laser beam  116  passes through the space  107  between the reflection mirror  64  and the bottom surface mirror  65  and is emitted as the scanning laser beam  108  from the window  105 . The scanning laser beam  108  travels obliquely downward from the window  105  SO that the scanning line pattern  109  is formed. When the operator moves a boat-shaped article under the scanner unit  51 A a  so that the dish  10  is facing downward and the bar code label  13  is facing upward, a bar code formed on the bar code label  13  is scanned by the scanning laser beam  108  so as to be optically read. 
     A description will now be given, with reference to FIG. 19, of a fifth embodiment of the present invention. 
     Referring to FIG. 19, a bar code reading apparatus  150  has a scanner unit  51 B a  supported by the posts  52  and  53 . The scanner unit  51 B a  is formed of a main body  51   a  and the optical guide unit  121  mounted on the main body  51   a . The optical system  59 B a  as shown in FIG. 17 is mounted in the main body  51   a.    
     In a normal case, the scanning laser beams  79 ,  80 , and  81  travel obliquely upward from the window  54  of the main body  51   a  so that the scanning line pattern  82  is formed in the space above the main body  51   a . In this case, no laser beam is emitted from the optical guide unit  121 . 
     When the operation nob  141  is rotated in the direction shown by the arrow  144  (the counterclockwise direction), the laser beam reflected by the reflection mirror  64  passes through the transmission hologram plate  115  and travels to the optical guide unit  121 . The laser beam is propagated through the optical guided unit  121  and emitted from the window  121   d  thereof. As a result, the scanning laser beam  123  travels obliquely downward from the window  121   d  so that the scanning line pattern  124  is formed in the space above the main body  51   a.    
     Accordingly, the bar code reading apparatus  150  in the fifth embodiment has the same advantages as that shown in FIG.  14 . 
     FIG. 20 shows an evaluation of the bar code recording apparatuses according to the first to fifth embodiments in comparison with the conventional types of bar code recording apparatuses. 
     Referring to FIG. 20, as has been described above, as to the first type of conventional apparatus shown in FIG. 1, the evaluations regarding the items “MOVING OF ARTICLE BASKET” and “HANDLING OF BOAT-SHAPED ARTICLE” are bad, as to the second type of conventional apparatus shown in FIG.2, the evaluation regarding an item “QUICK HANDLING OF ARTICLE” is bad and the evaluation regarding the item “HANDLING OF BOAT-SHAPED ARTICLE” is ordinary, and as to the third type of conventional apparatus shown in FIG. 3, the evaluation regarding the items “QUICK HANDLING OF ARTICLE” and “PROTECTION FROM READING BAR CODE OF ARTICLE IN ARTICLE BASKET” are bad. On the other hand, as has been described above, as to the apparatuses  100 ,  120 ,  140 ,  150  according to the second to fifth embodiments, the evaluations regarding all the above items are good. As to the apparatus  50  according to the first embodiment, although the evaluation regarding the item of “HANDLING OF BOAT-SHAPED ARTICLE” is bad, the evaluation regarding the other items are good. 
     A description will now be given, with reference to FIGS. 21,  22 A and  22 B, of another embodiment of the present invention. In FIGS. 21,  22 A and  22 B, those parts which are the same as those shown in FIG. 6 are given the same reference numbers. 
     FIG. 21 shows a scanner unit  161 . Referring to FIG. 21, an optical system  59 D is mounted in the scanner unit  161 . The optical system  59 D has the same structure as the optical system  59  shown in FIG. 6, except that a transmission hologram plate  162  located between the bottom surface mirror  65  and the window  54  is additionally provided. A rod, on the tip end of which an operation nob  163  is fixed, is connected to the transmission hologram plate  162  so that the inclination angle of the transmission hologram plate  162  can be controlled by rotation of the operation nob  163 . 
     In a case where the scanner unit  161  is used in the horizontal setting form as shown in FIG. 1, the operation nob  163  is rotated and locked at a predetermined position so that the transmission hologram plate  161  is maintained in a state as shown in FIG.  22 A. In this state, the laser beam reflected by each of the reflection mirrors  62 ,  63  and  64  and the bottom surface mirror  65  is incident to the transmission hologram plate  162  at an incident angle δ. The incident angle δ is greatly different from the Bragg angle of the transmission hologram plate  162 . Thus, the laser beam  164  reflected by the bottom surface mirror  65  passes through the transmission hologram plate  162 . The laser beam  166  which has passed through the transmission hologram plate  166  travels obliquely upward through the window  54 . 
     In this case, the scanner unit  161  is set on the check-out counter  21  so that the window  54  faces upward as shown in FIG. 21 (in the horizontal setting form). As a result, the scanning laser beams travels obliquely upward from the window  54  so that the scanning line pattern  82  is formed. 
     In a case where the scanner unit  161  is used in the vertical setting form as shown in FIG. 2, the operation nob  163  is rotated and locked at a predetermined position so that the transmission hologram plate  162  is maintained in a state as shown in FIG.  22 B. In this state, the laser beam reflected by each of the mirrors  62 ,  63  and  64  and the bottom surface mirror  65  is incident to the transmission hologram plate  162  at an incident angle ε. The incident angle ε is equal to the Bragg angle of the transmission hologram plate  162 . Thus, the laser beam  164  reflected by the bottom surface mirror  65  is diffracted by the transmission hologram plate  162 . The diffracted laser beam  166  from the transmission hologram plate  162  travels through the window  54  in a direction approximately perpendicular to the surface of the window  54 . 
     In this case, the scanner unit  161  is set on the side of the check-out counter  21  opposite to the side of the check-out counter  21  on which the operator stands, as shown in FIG.  2 . 
     In this embodiment, the scanner unit  161  can be used in both the horizontal setting form and the vertical setting form. That is, the scanner unit  161  can be used as both a component of the first type of bar code reading apparatus as shown in FIG.  1  and the second type of bar code reading apparatus as shown in FIG.  2 . 
     A description will now be given, with reference to FIGS. 23,  24 A and  24 B, of another embodiment of the present invention. In FIGS. 23,  24 A and  24 E, those parts which are the same as those shown in FIG. 6 are given the same reference numbers. 
     FIG. 23 shows a scanner unit  171 . Referring to FIG. 23, an optical system  59 E is mounted in the scanner unit  171 . The optical system  59 E has the same structure as the optical system  59  shown in FIG. 6, except that a transmission hologram plate  172  located between the bottom surface mirror  65  and the window  54  is additionally provided. A rod, on the tip end of which an operation nob  173  is fixed, is connected to the transmission hologram plate  172 . The rod passes through a slotted hole  174  formed on a housing of the scanner unit  171 , and the operation nob  173  is located outside the housing. The transmission hologram plate  172  can be moved by the operation of the operation nob  173  in a direction parallel to a direction in which the slotted hole  174  extends. 
     In a case where the scanner unit  171  is used in the vertical setting form as shown in FIG. 2, the operation nob  173  is moved along the slotted hole  174  in a direction shown by an arrow  175  and is locked so that the transmission hologram plate  172  is maintained in a state shown in FIG.  24 A. In this state, the transmission hologram plate  172  is located near the bottom surface mirror  65 . The laser beam reflected by each of the reflection mirrors  62 ,  63  and  64  and the bottom surface mirror  65  is incident to the transmission hologram plate  172  at an incident angle σ. The incident angle σ is equal to the Bragg angle of the transmission hologram plate  172 . Thus, the reflected laser beam  164  from the bottom surface mirror  65  is diffracted and the diffracted laser beam  180  travels from the window  54  in a direction approximately perpendicular to the surface of the window  54 . A beam-waist  181  of the laser beam  180  traveling from the window  54  is located at a position separated from the window  54  by a length f which is relatively great. In this case, a length g of an optimum reading region  182  in which bar codes can be read is large. That is, the depth is large. 
     The scanner unit  171  is set on the side of the check-out counter  21  opposite to the side of the check-out counter  21  on which the operator stands, as shown in FIG.  2 . 
     In a case where the scanner unit  171  is used in the overhead setting form as shown in FIG. 3, the operation nob  173  is moved along the slotted hole  174  in a direction shown by an arrow  176  and is locked so that the transmission hologram plate  172  is moved without changing the incident angle a of the reflected laser beam  164  and maintained in a state shown in FIG.  24 B. In this state, the transmission hologram plate  172  is located near the window  54  opposite to the bottom surface mirror  65 . The reflected laser beam  164  from the bottom surface mirror  65  is diffracted and the diffracted laser beam  190  travels from the window  54  in a direction approximately perpendicular to the surface of the window  54 . A beam-waist  191  of the laser beam  190  traveling from the window  54  is located at a position separated from the window  54  by a length i which is less than the length f in the above case. In this case, a length j of an optimum reading region  192  in which bar codes can be read is less than the length g of the optimum reading region  182  in the above case. That is, the depth is decreased. 
     The scanner unit  171  is set on the check-out counter  21  so that the window  54  faces downward as shown in FIG.  3 . In this case, even if the laser beam travels downward from the window  54  of the scanner unit  171 , since the length j of the optimum reading region  192  is small, hardly any bar codes on articles in the article basket  24  are read by using the laser beam. 
     In this embodiment, the scanner unit  171  can be used in both the vertical setting form and the overhead setting form by the selecting operation of the operation nob  173 . That is, the scanner unit  171  can be used as both a component of the first type of bar code reading apparatus as shown in FIG.  1  and the second type of bar code reading apparatus as shown in FIG.  2 . 
     The present invention is not limited to the aforementioned embodiments, and variations and modifications may be made without departing from the scope of the claimed invention.