Optical information reader

• US 5,597,997 A
• Filed: 10/05/1995
• Issued: 01/28/1997
• Est. Priority Date: 12/18/1992
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Watanabe, Takeshi, Nojiri, Tadao, Teramae, Kouji, Kitazumi, Yosimi, Obata, Kenzo
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Le, Thien Minh
• Application Number:
  US08/540,239
• Time in Patent Office: 481 Days
• Field of Search: 235/454, 235/455, 235/462, 235/472, 235/470
• US Class Current: 235/455
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10752 Exposure time control
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03

Abstract

To accurately read optical information more than an opening diameter of a read opening without the read opening contacted with a reading object, in a reader for reading a bar code by irradiating light from a light source to a bar-code label, converging the reflected light through a mirror and a stop by a lens and focusing the converged light on a line image sensor with a shutter, a wavelength detector for detecting a wavelength of the reflected light and a light guide for irradiating light spots indicative of a readable range to the label are provided. Whether a reading state is in a contact reading state in which a read opening contacts the label or in a noncontact reading state in which the read opening separates from the label is determined based on a wavelength of the reflected light detected by the wavelength detector. A light emission quantity and a shutter speed are controlled so as to keep an incident light quantity to the image sensor at an optimum value on a basis of the decided result and reflected light intensity obtained by integrating a line sensor output.

Claims

1. An optical code information reader shaped as a hand-held type to be used in contact with and away from optical code information on a read object, said reader comprising:

a casing shaped to be held by hand, said casing having an opening;

light source means disposed in said casing for irradiating light to the read object having optical code information thereon;

an optical system for converging reflected light which is reflected by said reading object to enter through the opening and for focusing information image indicative of the optical code information on a predetermined reading position, said optical system including an iris;

image sensor means, having a scanning period and a shutter function and being arranged at the predetermined reading position, for converting the optical code information image into an electrical signal in accordance with the shutter function;

light intensity detection means for detecting, from a value of said electrical signal of said image sensor means, an intensity of the reflected light;

control means for controlling a shutter speed of said shutter function of said image sensor means in response to an output signal of said light intensity detection means so that said image sensor means operates with an optimum exposure condition; and

guide light means in said casing for irradiating a guide light to said read object so that a readable image is indicated thereby without interfering with light passing through said iris.

2. An optical information reader as claimed in claim 1, wherein said light guide means is located in front of and away from said image sensor means.

3. An optical information reader as claimed in claim 2, wherein said light guide means and said light source means use a common light source located near said read opening.

4. An optical information reader as claimed in claim 1 further comprising:

reading state decision means for deciding whether a reading state is in a contact-reading state in which said read opening contacts said reading object or in a noncontact-reading state in which said reading opening separates from said reading object; and

said control means controlling the exposure time on a basis of the detected result of said light intensity detection means and the decision result of said reading state decision means.

5. An optical information reader as claimed in claim 4, wherein said reading state decision means includes:

wavelength detection means for detecting a wavelength of reflected light reflected by said reading object when said light source means has irradiated light; and

wavelength decision means for deciding based on a wavelength of the detected reflected light as to whether the reflected light is reflected light caused by light which said light source means has irradiated or reflected light including external light other than from said light source means.

6. An optical information reader as claimed in claim 4, wherein said reading state decision means reads, from said light intensity detection means, reflected light intensity when said light source means has irradiated light and reflected light intensity when said light source means does not irradiate light, and decides a reading state of the optical information on a basis of a ratio of both the reflected light intensity.

7. An optical information reader as claimed in claim 4, wherein said reading state decision means includes:

reflected light width detection means for detecting a width of reflected light caused by irradiation of the guide light on a basis of an electric signal outputted by said image sensor means when said light guide means has irradiated the guide light, so that said reading state decision means decides a reading state of the optical information on a basis of the detected width of the reflected light.

8. An optical information reader as claimed in claim 1, wherein said light source means includes:

a large number of light emission diodes which are arranged at more than two rows in a width direction of said read opening such that irradiating directions of light of the respective rows are set in directions different from each other.

9. An optical information reader as claimed in claim 1 further comprising:

an outer wall slanted along an angular range in which said optical system for imaging converges the reflected light.

10. The reader of claim 1, wherein said guide light means includes a pair of light emitting diodes provided at opposite sides of said iris.

11. The reader of claim 10, wherein guide light from said pair of diodes crosses inside said casing to form a pair of light spots indicating a readable range on opposite sides of said object to be read, said pair of light spots crossing inside said casing and emerging from said opening.

12. An optical information reader as claimed in claim 1 wherein said control means controls the light emission quantity together with the exposure time of said image sensor means.

18. Optical information reader apparatus according to claim 11, wherein a first one of said detection devices has a first sensitivity peak at a first wavelength corresponding to said light from said light source means and a second one of said detecting devices has a second sensitivity peak at a second wavelength corresponding to light from other than said light source means.

19. Optical information reader apparatus according to claim 11, wherein said second deciding means performs the deciding operation thereof in response to intensity of light of said first wavelength.

13. An optical information reader apparatus comprising:

casing means shaped to be held by a hand and provided with an opening;

light source means provided in said casing means for projecting light to an object recorded with optical information to be read;

optical focusing means provided in said casing means for collecting reflection light from said object and focusing the same so that an optical image of said optical information is provided at a predetermined reading position;

image reading means, having a shutter function to control a light exposure time of light focused by said optical focusing means and provided at said predetermined reading position in said casing, for converting said optical image into an electric signal in accordance with the shutter function;

wavelength detecting means provided in said casing for detecting wavelength of said reflection light;

first deciding means for deciding, in response to detected wavelength, whether said reflection light is caused by the light from said light source means or includes ambient light outside said casing means;

second deciding means for deciding, in response to said detected wavelength, whether said opening is in contact with said object or spaced apart from said object; and

control means for controlling in response to decision results of said first and second deciding means, the shutter function of said image reading means.

14. Optical information reader apparatus according to claim 13, wherein said control means controls said light exposure time to a minimum time at initial stage and thereafter to a longer time gradually.

15. Optical information reader apparatus according to claim 13, wherein said second deciding means operates only after said first deciding means has decided that said reflection light is caused by said light from said light source means.

16. The apparatus of claim 13, wherein:

said optical focusing means includes an iris for focusing said reflection light; and

said apparatus further includes guide light means in said casing for irradating a guide light on said object so that a readable image is indicated thereby without interfering with light passing through said iris, said guide light means emitting blinking light using electric power from a power source.

17. Optical information reader apparatus according to claim 15, wherein said wavelength detecting means includes a plurality of detection devices having respective sensitivity peaks different from each other.

20. Optical information reader apparatus according to claim 13, wherein said control means controls said light exposure time in accordance with an amount of light received by said image reading means, when said first deciding means has decided that said second wavelength is included in said reflection light.

21. Optical information reader apparatus according to claim 20, wherein said light source means changes intensity of said light when said light exposure time exceeds a predetermined time.

22. An optical information reader apparatus comprising:

casing means shaped to be held by a hand a provided with an opening;

light source means provided in said casing means for projecting light to an object recorded with optical information to be read;

optical focusing means provided in said casing means for collecting reflection light from said object and focusing the same so that an optical/image of said optical information is provided at a predetermine reading position;

image reading means, having a shutter function and being provided at said predetermined reading position in said casing, for converting said optical image into an electric signal in accordance with the shutter function;

guide light means provided adjacent to said optical focusing means in said casing for irradiating a guide light to said object so that a readable range is indicated thereby; and

control means for controlling said guide light means in response to at least one of a mean value of the electric signal indicative of an intensity of said reflected light and reading operation of said image reading means.

28. An optical information reader apparatus according to claim 22, wherein said control means is further for, when said optical information reader apparatus is in a contact reading state, controlling said guide light means to cause said guide light means to extinguish said guide light, and when said optical information reader apparatus is in a noncontact reading state, controlling said guide light means to cause said guide light means to generate said guide light.

23. An optical information reader apparatus comprising:

casing means to be held by a hand and provided with an opening;

light source means provided in said casing means for projecting light onto an object recorded with optical information to be read;

optical focusing means provided in said casing means for collecting reflection light from said object and focusing the same so that an optical image of said optical information is provided at a predetermined reading position;

image reading means provided at said predetermined reading position in said casing for converting said optical image into an electric signal;

wavelength detecting means provided in said casing and including a plurality of detection devices having respective sensitivity peak different from each other, for detecting wavelength of said reflection light;

first deciding means for deciding, in response to detected wavelength, whether said reflection light is caused by the light from said light source means or include ambient light outside said casing means;

second deciding means for deciding, in response to said detected wavelength, whether said opening is in contact with said object or spaced apart from said object; and

control means for controlling response to decision results of said first and second deciding means, light exposure time of said image reading means.

24. Optical information reader apparatus according to claim 23, wherein first one of said detection devices has a first sensitivity peak at a first wavelength corresponding to said light from said light source means and second one of said detecting devices has a second sensitivity peak at a second wavelength corresponding to light other than said light source means.

25. Optical information reader apparatus according to claim 23, wherein said second deciding means performs deciding operation thereof in response to intensity of light of said first wavelength.

26. An optical information reader shaped in a hand-held type to be used in contact with and away from an optical information on a read object, said reader comprising:

light source means for irradiating light to said read object on which said optical information is recorded;

an optical system for converging reflected light within a predetermined angular range which is reflected by said read object to enter through a read opening and for focusing an information image indicative of said optical information on a predetermined reading position;

image sensor means, having a shutter function and being arranged at the reading position, for converting the information image into an electrical signal;

light intensity detection means for detecting, from a mean value of said electrical signal of said image sensor means, an average intensity of the reflected light each time said image sensor means performs reading operation thereof; and

control means for controlling a shutter speed of said shutter function of said image sensor means in response to an output signal of said detection means so that said image sensor means operates with an optimum exposure condition,

wherein said control means includes;

determining means for determining whether the output signal of said detection means is above a predetermined value;

speed changing means for changing a shutter speed of said image sensor means by a predetermined amount; and

repeating means for repeating a speed changing operation of said speed changing means until said output signal reaches said predetermined value.

27. A reader according to claim 26, wherein said detection means includes an integrator for integrating said electrical signal of said image sensor means to obtain the mean value.