CN104008358B - Code reading device - Google Patents
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- CN104008358B CN104008358B CN201410067342.5A CN201410067342A CN104008358B CN 104008358 B CN104008358 B CN 104008358B CN 201410067342 A CN201410067342 A CN 201410067342A CN 104008358 B CN104008358 B CN 104008358B
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Abstract
Thering is provided a kind of code reading device, it is bigger than conventional code reading device that it reads distance range.Possessing from the code reading device of object readout code: image unit, shooting is imaged on the optical image of sensitive surface；Depth of field expanding unit, in predetermined reading distance range, independently obtains focusedimage with the distance with described object；Optical transform element, make the optical image distortion of shooting in the following manner so that the general image that the focusedimage when the beeline of described reading distance range comprises described code and the focusedimage when the longest distance of described reading distance range at least distribute predetermined pixel count to the unit image of described code.
Description
Technical field
The present invention relates to a yard reading device.
Background technology
In the past, one read the code reading of the Quick Response Code such as the one-dimension code such as bar code, QR code (registered trade mark) optically
Device is known.The expansion reading distance range of code reading device, can significantly improve the commodity value of yard reading device.For
Expand and read distance range, need the technology of a kind of extended depth of field.The depth of field refers to visible subject under focus state
The distance range of side.
The image restoration that patent document 1 discloses that to have in phase-plate optical system and frequency space is processed as feature
" there is the optical system of the extended depth of field ".In the optical system that patent documentation 1 is recorded, expand the depth of field, and can
The image of focusing is obtained in bigger distance range.But, the optical system that patent documentation 1 is recorded simply expands merely scape
Deeply, the reading distance range of code can not be expanded to greatest extent.
Here, pixel distribution when considering the code of shooting same size.It is projected to the whole of imaging apparatus be subject near field
Code on bright finish, is projected to a part for sensitive surface in far field.Being assigned to the pixel count of a unit of code, far field is than near
Field is less.That is, need in far field more higher resolution than near field.
Such as, once it is determined that read distance range, yardstick cun and cell size, then can be according to the yardstick under beeline
The very little angle of visual field determining camera system, distributes the resolution determining necessity according to the pixel under longest distance.And, there is root
The relation of pixel count necessary to imaging apparatus is determined according to the angle of visual field and resolution.It practice, be in most cases according to cost
Viewpoint first determine the pixel count of imaging apparatus, determine longest distance according to resolution.Therefore, if simply expanding merely scape
Deeply, code beyond picture etc., thus can limit the reading distance near field due to the rule of picture.
Automatic condenser lens is used to read " code reader " of distance range to expand code it addition, non-patent literature 1 discloses.
Automatically by the way of condenser lens mode is the spacing that the movement by lens changes lens and imaging apparatus sensitive surface.Certainly
In the code reader of dynamic condenser lens mode, need the drive mechanism of mobile lens.It addition, patent document 2 discloses that use is variable
Punktal lens reads " code reader " of distance range to expand code.Varifocal lens mode is to change the focal length of lens
Mode.In the code reader of Varifocal lens mode, need to change the mechanism of the focal length of lens.
Citation
Patent documentation
Patent documentation 1: No. 3275010 publications of Japanese Patent Publication No.
Patent documentation 2: Japanese Unexamined Patent Application Publication 2012-515359 publication
Non-patent literature
Non-patent literature 1: the catalogue of the portable wireless scanning device (ProductName " SR61ex ") of Intermec company
Summary of the invention
The present invention makes in view of the foregoing, its object is to provide a kind of code reading device, and it is than conventional code
Reading device has bigger reading distance range.
For reaching above-mentioned purpose, the invention of the first embodiment is the code reading device from object readout code, and it possesses:
Image unit, shooting is imaged on the optical image of sensitive surface；Depth of field expanding unit, in predetermined reading distance range, with institute
The distance stating object independently obtains focusedimage；Optical transform element, makes the optical image distortion of shooting in the following manner, makes
Obtain general image that the focusedimage when the beeline of described reading distance range comprises described code and described reading away from
Focusedimage when the longest distance of scope at least distributes predetermined pixel count to the unit image of described code.
Can also be that, in the case of the distance with described object is shorter than preset distance, described optical transform element makes
The curvature of the image of the optical image of shooting so that the focal position of described imaging apparatus periphery is than the central part of described imaging apparatus
Focal position closer to sensitive surface.
For achieving the above object, the invention of the 3rd embodiment is the code reading device from object readout code, and it possesses:
Image unit, shooting is imaged on the optical image of sensitive surface；First optical transform element, utilizes intrinsic transforming function transformation function to change incidence
The wavefront of light so that can shoot with the optical image unrelated with the distance of described object in predetermined reading distance range；Figure
As processing unit, use the inverse function of described transforming function transformation function that shooting image is carried out image procossing so that predetermined reading away from
In the range of from, can be from the focusedimage of object described in shooting image restoration；Second optical transform element, is arranged in described first
The light incident side of optical transform element, makes the optical image distortion of shooting in the following manner so that at described reading distance range
General image that restored image during beeline comprises described code and answering when the longest distance of described reading distance range
Original image at least distributes predetermined pixel count to the unit image of described code.
Can also be, in the case of the distance with described object is shorter than preset distance, described second optical transform list
Unit makes the curvature of the image of the optical image of shooting so that the focal position of the periphery of described imaging apparatus is than described imaging apparatus
The focal position of central part is closer to sensitive surface.
Can also be that described second optical transform element is the optical system at least with lens, described first light
Learn the phase-modulation face that converter unit is formed in described optical system.
Invention effect
Code reading device according to the present invention, it is possible to expand the reading distance range of code, and can be read by a code
Fetching puts the image read near field to far field.
Accompanying drawing explanation
Fig. 1 is the block diagram of the structure of the code reading device representing that embodiments of the present invention relate to.
Fig. 2 A is the cuing open along optical axis that the optical system of the code reading device representing that embodiments of the present invention relate to unifies example
View.Fig. 2 B is to represent the sectional view along optical axis that the optical system comprising phase-modulation face unifies example.
Fig. 3 A and Fig. 3 B is the explanatory diagram of the adquisitiones representing point spread function (PSF).
Fig. 4 A is the block diagram of the structure of the control system of the code reading device representing that embodiments of the present invention relate to.Fig. 4 B
It it is the functional block diagram controlling device.
Fig. 5 is that the explanatory diagram that the depth of field expands principle is described.
Fig. 6 A～6C is the explanatory diagram of the effect for additional distorted optical system is described.
Fig. 7 is the ideograph for field expander based on additional distorted optical system is described.
Fig. 8 A, 8B are to represent that MTF's (modulation transfer function (MTF)) responds the figure different according to the presence or absence of phase modulation component
Table.
Fig. 9 A, 9B are the sectional views along optical axis of the design example representing the additional distorted optical system utilizing curvature of the image.
Fig. 9 A represents that the situation of the curvature of the image near field, Fig. 9 B represent the situation of the curvature of the image in far field.
Description of reference numerals
10, code reading device 14, optical system
16, imaging apparatus 16A, sensitive surface
18, additional distorted optical system (the second optical transform element)
20A, phase-modulation face 20, phase modulation component (the first optical transform element)
22, imaging apparatus drive division 24, control device
26, image processing part 28, decoder unit
30, storage part 32, PSF (point spread function)
34, correction parameter 36, decoding table
L, optical axis O, object P, point source
I, image C, code R, camera watch region (picture)
DF, longest distance DN, beeline θN, the angle of visual field
θF, angle of visual field SI, focus face
Detailed description of the invention
Hereinafter, an example of the embodiment that present invention will be described in detail with reference to the accompanying.
Structure ＞ of ＜ code reading device
(overall structure)
First, the overall structure of description code reading device.
Fig. 1 is the block diagram of the structure of the code reading device representing that embodiments of the present invention relate to.As it is shown in figure 1, code is read
Fetching puts 10 optical systems 14 possessing the optical image forming object O, shoots the imaging apparatus 16 of the optical image being imaged, and
The image being taken is carried out the image processing part 26 of image procossing.Optical system 14, imaging apparatus 16 and image processing part 26
It is arranged in the basket (not shown) with window portion.The light scattered by object O incides optical system 14 by window portion.Optical system
System 14 possesses the phase modulation unit 20 as the first optical transform element, and be provided simultaneously with as the second optical transform element is attached
Add distorted optical system 18.Here, object O refers to be attached with the reading object thing of code.
In above-mentioned code reading device 10, incided the ripple of the light of optical system 14 by phase modulation component 20 conversion
Before, even if changing with the distance of object O, also shoot the image of same fog-level.It addition, performed bat by image processing part 26
Take the photograph image and implement the such image procossing of inverse transformation, thus restore focusedimage (removing fuzzy image).In predetermined distance
Scope (reading distance range), can carry out not relying on shooting and the recovery of above-mentioned distance, and the depth of field expands.The expansion of the above-mentioned depth of field
Method is referred to as wavefront coded method (Wavefront Coding).Further, the expansion principle of the depth of field is described below.
It addition, in above-mentioned code reading device 10, by the additional distorted optical system 18 light to being shot by imaging apparatus 16
Learn as additional distortion.Additional distorted optical system 18 makes optical image distortion in the following manner: make reading distance range
When restored image during short distance comprises all images of code, beeline, whole code is incorporated in picture.Furthermore, additional
Distorted optical system 18 makes optical image distortion in the following manner: make the restored image when reading the longest distance of distance range
In, at least distribute predetermined pixel count to the unit image (image of 1 unit) of code, i.e. also can resolve code when longest distance
1 cell picture.
Produced the image of distortion by additional distorted optical system 18, be corrected by the digital processing in image processing part 26
For distortionless image.By above-mentioned additional distortion and distortion correction, expand visual field during near field, when guaranteeing far field simultaneously
Pixel distribution, substantially expand read distance range.That is, by possessing phase modulation component 20 and additional distorted optical system
18, solve the simply simple insurmountable problem of extended depth of field.Expand the visual field later, pixel distribution guarantees to carry out
Describe in detail.
(structure of optical system)
Then, the structure of the optical system of description code reading device.
Fig. 2 A is the cuing open along optical axis that the optical system of the code reading device representing that embodiments of the present invention relate to unifies example
View.
As shown in Figure 2 A, additional distorted optical system 18, phase modulation component 20 and imaging apparatus 16 are respectively along optical axis L
Start to configure in the order described above from object O side.In the example in the figures, use have at optical axis direction intrinsic concavo-convex
The three dimensional Phase plate of (thickness distribution) is as phase modulation component 20.Intrinsic concavo-convex such as by curved phase place of phase-plate
Modulation face 20A realizes.Phase modulation component 20 makes phase-modulation face 20A towards additional distorted optical system 18 side, and joins
Put the rear side (aperture position) in additional distorted optical system 18.
Incide the light of optical system 14 by additional distorted optical system 18, and by after phase modulation component 20,
The sensitive surface 16A imaging of imaging apparatus 16.As it has been described above, the shooting image of object O is added abnormal by additional distorted optical system 18
Become, formed the deterioration image of defocusing by phase modulation component 20.
As imaging apparatus 16, it is possible to use by the imageing sensor etc. of light-to-current inversion shooting optical image.As image
Sensor, can enumerate CCD (Charge Coupled Device) imageing sensor, CMOS (Complementary Metal
Oxide Semiconductor) imageing sensor etc..
Additional distorted optical system 18 could be arranged to, and the restored image when reading the beeline of distance range comprises
The general image of code and the restored image when longest distance distribute predetermined to the unit image (image of 1 unit) of code
Pixel count.Additional distorted optical system 18 can be made up of single optical element, it is also possible to by the one of compound lens etc. group of light
Element is constituted.In the present embodiment, as additional distorted optical system 18, it is possible to use make at periphery compression image
The distortion optical system of image fault.As distorting optical system, it is possible to use more compressed from the most past outside of central part, image
The concentrically compression such as " fish-eye lens " of round shape optical system.
In the optical system shown in Fig. 2 A, use phase-plate is as phase modulation component 20, if phase modulation component 20
It it is the optical element with the function (phase-modulation function) before converting incident light wave.As phase modulation component 20, remove
Beyond the optical element (such as three dimensional Phase plate) of the thickness change of optical axis direction, it is possible to use the optics of variations in refractive index
Element (phase modulation component of such as distributed refractive index), liquid crystal cell (the such as liquid crystal spatial phase of phase-modulation can be carried out
Position modulation element) etc..The optics unit of thickness and refractive index is changed by lens surface is implemented coating furthermore it is also possible to use
Part (such as phase-modulation hybrid lens) etc..
Adjust furthermore it is possible to form the phase place as the first optical transform element in additional distorted optical system 18
Face 20A processed.Fig. 2 B is to represent the sectional view along optical axis that the optical system comprising phase-modulation face unifies example.Shown in Fig. 2 A and 2B
In example, additional distorted optical system 18 is the compound lens being made up of multiple lens.Light in additional distorted optical system 18
On one lens face of emitting side, it is formed with phase-modulation face 20A.By forming in additional distorted optical system 18
Phase-modulation face 20A, it is possible to reduce the quantity of parts, it is not required that the optical axis alignment of phase modulation unit.
(conversion characteristics of optical system)
Then, the conversion characteristics of optical system is described.
Fig. 3 A and 3B is the explanation of the adquisitiones representing point spread function (PSF:Point Spread Function)
Figure.In wavefront coded method, use point spread function (PSF) to show the conversion characteristics of optical system.PSF is to represent optical system
Function for the diffusance of point source.In other words, be performance shooting point light source time this point source shoot with how being blurred,
The function of the fuzzy manner of point source.
As shown in Figure 3A, the optical system 14 of code reading device 10 is used, by imaging apparatus 16 shooting point light source P.As
Shown in Fig. 3 B, corresponding to the image I of point source P in the sensitive surface 16A imaging of imaging apparatus 16.According to this image I, obtain optics
The PSF that system 14 is intrinsic.The PSF obtained is stored in the storage part 30 of control device 24 described later as controlling value.This enforcement
In mode, PSF uses as the function not relying on distance.Further, narrowly, although PSF is along with the distance with point source
And change, but can use as not relying on the function of distance in reading distance range.
(structure of control system)
Then, the structure of the control system of description code reading device.
Fig. 4 A represents the block diagram of the structure of the control system of the code reading device that embodiments of the present invention relate to.Fig. 4 B is
Control the functional block diagram of device.
As shown in Figure 4 A, code reading device 10 possesses for driving the imaging apparatus drive division 22 of imaging apparatus 16 and controlling
The control device 24 of imaging apparatus drive division 22.Such as, imaging apparatus drive division 22 is believed according to the control carrying out self-control device 24
Number drive each portion of imaging apparatus 16.It addition, imaging apparatus drive division 22 obtains the picture signal of simulation from imaging apparatus 16,
Carrying out converting (A/D conversion) is that data image signal etc. processes, then to the figure controlling the optical image that device 24 output is taken
As information.Control device 24 according to the image information obtained, code to be decoded, export decoding information.
As shown in Figure 4 B, control device 24 and possess image processing part 26, decoder unit 28 and storage part 30.In storage part 30
Storage has the PSF32 of the recovery for focusedimage, for correcting distorted correction parameter 34, and the translating of decoding for code
Code table 36.
Image processing part 26 reads the PSF32 of optical system 14 from storage part 30, performs shooting image is implemented inverse transformation
Such image procossing, restores and eliminates fuzzy focusedimage.It addition, image processing part 26 reads distortion school from storage part 30
Correction parameter 34 just, performs to carry out shooting image the image procossing of distortion correction, obtains the image not having distortion.Restore
Process and distortion correction processes and can perform in either order.Processed by these, obtain the focused view relating to not distorting
The image information of picture.
Extraction code image the decoder unit 28 image after image procossing, the decoding carrying out decoding code processes.Translate
Code processes and carries out based on the decoding table 36 read from storage part 30.The decoding information obtained by decoding process, from decoder unit 28
Output.Such as, if bar code, then the numeric string being made up of 0 and 1 corresponding to bar code it is decoded as.Or, it is right to be decoded as
Should be in the character string of numeric string.
Function ＞ of ＜ code reading device
Then, the function of description code reading device.As it has been described above, code reading device of the present embodiment possesses " scape
Deep expanded functionality ", " visual field expanded functionality " and " pixel distribute guarantee function ".Hereinafter, each function is illustrated.
(expanded functionality of the depth of field)
First, " depth of field expanded functionality " is further described.
Fig. 5 is that the explanatory diagram that the depth of field expands principle is described.In present embodiment, as it has been described above, utilize wavefront coded method
(Wavefront Coding) extended depth of field.
Here, simply illustrate the principle of wavefront coded method.Illustrate subject image F optical transition by optical system 14
Become shooting image G and be restored to restored image F by image procossingRSituation.Optical system 14 has PSF.From subject
Image F as shown in following formula, is similar to the convolution (Convolution) of PSF to the optical transition of shooting image G.
G=PSF*F (* represents convolution)
It addition, restore restored image F from shooting image GRImage procossing as shown in following formula, be similar to based on PSF
Inverse function (PSF)-1Convolution (Convolution).In other words, perform and the optical transfer function carried out by optical system 14
(OTF) Filtering Processing that the inverse transformation of change is suitable.
FR=(PSF)-1* G (* represents convolution)
As it is shown in figure 5, in the case of shooting addition of the object of yard C, object remotely located time-code C occupies imaging region
A part of territory R, object is positioned at time-code C nearby and occupies the most whole of camera watch region R.Hereinafter, camera watch region R is referred to as
Picture.In the case of not using wavefront coded method, no matter near field or far field, if object deviation focal position, then can clap
Take the photograph fuzzy image.Its fog-level changes along with the distance (side-play amount) from focal position to object.
Employ in the present embodiment of wavefront coded method, in predetermined reading distance range, become by above-mentioned optics
Change, with the shooting image G that independently have taken identical fog-level with the distance of object.It addition, in the present embodiment, light
The PSF of system 14 is not dependent on the function of distance.Therefore, in predetermined reading distance range, by above-mentioned image
Process, with the distance with object independently, restored, according to shooting image G, the restored image F focused onR。
(visual field expanded functionality)
Then, " visual field expanded functionality " is further described.
Fig. 6 A～6C is the explanatory diagram of the effect that additional distorted optical system is described.Fig. 7 is based on additional abnormal for explanation
Become the ideograph of the visual field expanded functionality of optical system.
Additional distorted optical system 18 makes optical image distortion in the following manner: when making the beeline reading distance range
Restored image comprise the general image of code.As shown in Figure 6B, the subject image F shown in Fig. 6 A is taken into the figure of periphery
As the distortion image G more significantly compressed than central part.The distortion of periphery is big, and the distortion of central part is little.Such as, read near field
In the case of QR code (registered trade mark), shooting distortion image G as shown in Fig. 6 C.
Knowable to Fig. 6 C, by making image fault, even if near field, it is also possible to code is all accommodated in picture.Such as figure
Shown in 6A, 6B, processed by the distortion correction after shooting, restore, from distorting image G, the restored image F not having to distortR.That is, multiple
The image of the former periphery compressed, reverts to distortionless image.
As it is shown in fig. 7, the result of extended depth of field, from beeline DNTo longest distance DFReading distance range Δ D in,
It is not only restricted to the distance with object, it is possible to obtain the restored image focused on." datum mark " herein is equipped with phase-modulation
" aperture position " of the phase-modulation face 20A of element 20.
If being positioned at beeline DNClosest approach subject, by the additional additional distortion of distorted optical system 18
Result, the code C being attached on object is accommodated in camera watch region, and can obtain comprising the restored image of yard image.
That is, by the additional distortion of additional distorted optical system 18, it is possible to expand visual field during closest approach, can carry out in angle of visual field θN(>
θF) wide angle shot.Such as, the visual field is expanded into 1.4 times.The expansion in visual field during closest approach, substantially expands the depth of field.Also
Have, angle of visual field θFIt is in longest distance DFSolstics time the angle of visual field.
(the guaranteeing function of pixel distribution)
It follows that further describe " pixel distribution guarantees function " with reference to Fig. 7.
As it has been described above, according to additional distorted optical system 18, concentricity portion compares, the image of periphery is pressed significantly
Contracting.In near field, owing to code C occupies the most whole surface of picture, the pixel thus for the unit picture element (1 unit) of code C is divided
Distribution transforming is many.On the other hand, in far field, owing to code C only occupies a part for picture, the pixel thus for 1 unit of code C is divided
Distribution transforming is few.If the pixel distribution for 1 unit of code C is few, then it is easily subject to the impact of additional distorted optical system 18.
That is, even if at the less central part that distorts compared with periphery, it is also difficult to restore the code image of undistorted shape.
In view of the foregoing, additional distorted optical system 18 makes optical image distortion in the following manner: make reading distance
Longest distance D of scopeFTime restored image in, at least distribute predetermined pixel count to the unit image (1 unit) of code C.
It is being in longest distance DFSolstics make optical image distortion in the following manner: the pixel of 1 unit for code C is distributed
More than predetermined pixel count.Such as, the pixel for 1 unit of code C is assigned as more than 2 pixels.Thus, even if farthest
Point, it is also possible to tell 1 unit of yard C.
Further, in far field, code C occupies the central part of picture.Therefore, additional distorted optical system 18 may be designed as central part
Resolution resolution high, periphery low.By such design, in solstics, it is possible to make 1 unit for code C
The predetermined pixel count of pixel distribution ratio many.
It addition, as shown in Fig. 9 A, 9B, if using additional distorted optical system 18, due to central part and the periphery in the visual field
The focal position in portion is different, it may occur that focus face SIThe phenomenon of (image planes of optical image) bending (curvature of the image).Can also be by attached
Add distorted optical system 18 to be designed to be able to actively utilize this curvature of the image.Hereinafter, it is specifically described.
In near field, as shown in Figure 9 A, the focal position of periphery than the focal position of central part closer to imaging apparatus 16
Sensitive surface 16A.I.e. do not focus on sensitive surface 16A in central part focus, but focus at periphery.For by additional distortion light
System 18 is compressed and the periphery of quantity of information minimizing, by focusing on sensitive surface 16A, easily carries out answering of periphery image
Former, and then easily realize decoding.Further, in far field, as shown in Figure 9 B focal position to optical system lateral deviation from.Jiao of bending
Point face SIAlso to optical system lateral deviation from, sensitive surface 16A cannot be focused in periphery focus, light can be focused at central part
Face 16A.
(embodiment)
Use general imaging apparatus, be read out the experiment of the code of unit size 1.0mm.Use conventional optical system
Can read more than 200mm 400mm following range of code, to this, the optical system using present embodiment can be at more than 120mm
Readout code in the scope of below 1200mm.Further, distance range (with the distance of focal position) is read according to unit size and light
The design of system and change.
(mediation of function)
Then, the mediation to " depth of field expanded functionality ", " visual field expanded functionality " and " pixel distribution guarantees function " is said
Bright.Fig. 8 A, 8B are that the response representing modulation transfer function (MTF) (MTF:Modulation Transfer Function) is according to phase place
The presence or absence of modulation element and different charts.Fig. 8 A is the chart of the response of the MTF in the case of indicating without phase modulation component, figure
8B is the chart of the response representing the MTF in the case of insertion phase modulation element.The longitudinal axis represents the value of normalized MTF, transverse axis
Representation space frequency (unit: cycle/mm).Further, the structure of optical system is as shown in Figure 2 A.
MTF is the index of the imaging performance representing optical system.Represent the order according to solid line → thick dashed line → fine dotted line,
Elongated with the distance of object.As shown in Figure 8 A, not in the focal position configuration phase modulation of additional distorted optical system 18
In the case of element 20, the longest with the distance of object, the response of MTF is the lowest.This represent optical system 14 imaging performance with
And change with the distance of object.
On the contrary, as shown in Figure 8 B, the focal position in additional distorted optical system 18 is configured with phase modulation component 20
In the case of, unrelated with the distance with object, the response of MTF is approximately certain value.This represents the imaging performance of optical system 14
Independently keep constant with the distance of object.According to this as a result, it is possible to be identified through phase modulation component 20 and make to add
The MTF distributing equilibrium of distorted optical system 18, obtains the image of identical fog-level, depth of field expanded.
As it has been described above, in the present embodiment, with the distance with object independently, the restored image focused on can be obtained.
That is, expand the depth of field, read distance range and become big.It addition, in the present embodiment, according to reading distance range, to being taken
The additional distortion of optical image.By additional distortion, expand the visual field near field so that in beeline shooting and the recovery of recovery
Image comprises the general image of code.It addition, by additional distortion, in the restored image of longest distance shooting and recovery, Xiang Yi
The pixel count that the distribution of individual unit is predetermined.Therefore, it is possible to read the image near field to far field by a code reading device.
＜ variation ＞
Further, in the respective embodiments described above, the structure of the code reading device of explanation is an example, undoubtedly, can not take off
This structure is changed in the range of present subject matter.
Such as, in the above-described embodiment, illustrate to utilize the situation of wavefront coded method extended depth of field, it is also possible to utilize it
His method extended depth of field.As the expansion method of the depth of field, such as, can enumerate notch shot (Coded Aperture), focus
Scanning method (Focus Sweep), chromatism method, lenticule method.About notch shot, focus scanning method, it is referred to Xiang Chuankang
Rich wait " the optical sensing technology of optically-based system shooting process signal processing method ", the accurate engineering of Japan can be miscellaneous
Will, Vo177, N12,2011.
Notch shot is according to the aperture in camera system, not only regulates light quantity, also by the point spread function of camera system
The method that number (PSF) carries out encoding.Due in preferable geometric optics system, the shape of the shape of aperture and the PSF on image
Shape is of equal value, thus can control the PSF of camera system according to light circular pattern.A kind of wideband frequency with inferred-zero intersection is proposed
The iris shape of characteristic, for stably restored image.Detailed content is documented in Zhou, C., Nayar.:What are good
apertures for defocus deblurring？In:International Conference of Computational
In the documents such as Photography, San Francisico, U.S. (2009).
Focus scanning method is to change the position of (focus scanning) imaging apparatus, the figure of multiple-exposure each point simultaneously in exposure
Picture, the method obtaining not relying on the PSF of distance.Detailed content is documented in Hajime Nagahara, Sujit
Kuthirummal,Changyin Zhou,Shree K.Nayar,Flexible Depth of Field Photography,
Proc.European Conf.Computer Vision, in the document such as No.LNCS 5305, PP.60-73,2008.10.
Chromatism method is according to increasing the special optical lens of aberration and colour filter array and special signal processing comes
The method of extended depth of field.Detailed content is documented in " the Depth of Field Expansion Technology of river and mountain etc.
Using Chromatic Aberration ", optics 40 (10), 528-533,2011-10-10, the branch meeting of Applied Physics association
In the document that Japanese Optical can wait.
Lenticule method is the method that the camera system by special lenses carrys out extended depth of field, and this special lenses has and is combined with
The lens that multiple focal lengths are different.Detailed content is documented in LEVIN, A., HASINOFF, S., GREEN, P., DuRAND, F.,
AND FREEMAN,W.2009.4D frequency analysis of computational cameras for depth
In the documents such as of field extension.MIT CSAIL TR 2009-019..
It addition, the code being attached on reading object thing can be the two dimension such as the one-dimension code such as bar code, QR code (registered trade mark)
Any one of code.
Claims (5)
1. a code reading device, from object readout code, it is characterised in that possess:
Imaging apparatus, shooting is imaged on the optical image of sensitive surface；
Depth of field expanding unit, in predetermined reading distance range, independently obtains focused view with the distance with described object
Picture；
Optical transform element, makes the optical image distortion of shooting in the following manner so that at the short distance of described reading distance range
From time focusedimage comprise the general image of described code and the focusedimage when the longest distance of described reading distance range
The middle unit image to described code at least distributes predetermined pixel count.
The most according to claim 1 yard of reading device, it is characterised in that
In the case of the distance with described object is shorter than preset distance, described optical transform element makes the optical image of shooting
Curvature of the image so that the focal position of described imaging apparatus periphery more connects than the focal position of the central part of described imaging apparatus
Nearly sensitive surface.
3. a code reading device, from object readout code, it is characterised in that possess:
Imaging apparatus, shooting is imaged on the optical image of sensitive surface；
First optical transform element, utilizes intrinsic transforming function transformation function to change the wavefront of incident illumination so that in predetermined reading distance
In the range of can shoot with the optical image unrelated with the distance of described object；
Graphics processing unit, uses the inverse function of described transforming function transformation function that shooting image is carried out image procossing so that predetermined
In reading distance range, can be from the focusedimage of object described in shooting image restoration；
Second optical transform element, is arranged in the light incident side of described first optical transform element, makes shooting in the following manner
Optical image distortion so that the restored image when the beeline of described reading distance range comprise described code general image,
And the restored image when the longest distance of described reading distance range at least distributes predetermined to the unit image of described code
Pixel count.
The most according to claim 3 yard of reading device, it is characterised in that
In the case of the distance with described object is shorter than preset distance, described second optical transform element makes the optics of shooting
The curvature of the image of picture so that the focal position of the periphery of described imaging apparatus is than the focus position of the central part of described imaging apparatus
Put closer to sensitive surface.
5. according to the code reading device described in claim 3 or claim 4, it is characterised in that
Described second optical transform element is the optical system at least with lens,
Described first optical transform element is formed in the phase-modulation face in described optical system.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2013-037929 | 2013-02-27 | ||
| JP2013037929A JP6017347B2 (en) | 2013-02-27 | 2013-02-27 | Code reader |
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| CN104008358B true CN104008358B (en) | 2016-11-30 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN202033765U (en) * | 2011-04-02 | 2011-11-09 | 北方国通（北京）光电科技有限公司 | Large-field-depth bar code scanner |
| CN102387294A (en) * | 2010-08-26 | 2012-03-21 | 富士胶片株式会社 | Shooting module and image signal processing method |
| CN102609931A (en) * | 2012-02-01 | 2012-07-25 | 广州市明美光电技术有限公司 | Field depth expanding method and device of microscopic image |
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102387294A (en) * | 2010-08-26 | 2012-03-21 | 富士胶片株式会社 | Shooting module and image signal processing method |
| CN202033765U (en) * | 2011-04-02 | 2011-11-09 | 北方国通（北京）光电科技有限公司 | Large-field-depth bar code scanner |
| CN102609931A (en) * | 2012-02-01 | 2012-07-25 | 广州市明美光电技术有限公司 | Field depth expanding method and device of microscopic image |
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