JP7367314B2 - Code reading device, code reading method and program - Google Patents

Description

The present invention relates to a code reading device , a code reading method , and a program.

Conventionally, when an image within a specified reading range of a prescan image read by prescan is analyzed, and if the maximum value of the output value of the prescan image is smaller than a threshold value, the maximum value of the output value of the prescan image is detected by the scanner device. An image reading control method has been disclosed in which the exposure time is adjusted to reach the maximum value of the dynamic range, and the image of the main scan is read (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2000-287040

However, the image reading control method disclosed in Patent Document 1 has a problem in that when reading a dark original, the scanning frame rate is lowered by adjusting the exposure time, so that reading takes time.

The present invention has been made in view of such problems, and an object of the present invention is to efficiently perform reading even in a dark place.

In order to solve the above problems, a code reading device according to the present invention is a code reading device that reads an optically readable code, and includes an imaging means for taking an image of the code, and an image taken by the imaging means. a decoding means for decoding the code based on an image of the code, and a subsequent image of the code by the imaging means based on the image of the code to be decoded when the decoding by the decoding means fails; Adjust the exposure time at the time of shooting and the output image size of the next code image , and make the next code image shoot with this adjusted exposure time, and adjust the output image size of the next code image. control means for controlling the output of an image of the code , the control means controlling the output of the image of the code based on the image of the code to be decoded when the decoding by the decoding means fails; When adjusting the exposure time when photographing the next and subsequent code images and the output image size of the next and subsequent code images, the next and subsequent code images are adjusted based on the brightness value of the code image targeted for decoding . When taking an image of the code, determine the candidate exposure time , and if the length of the determined candidate exposure time is shorter than the predetermined minimum exposure time, the exposure time is set to the minimum exposure time. The method is characterized in that the output image size is adjusted to a predetermined size while adjusting the time.
Further, the code reading method according to the present invention is a code reading method executed by a code reading device that reads an optically readable code, and includes an imaging step of photographing an image of the code; a decoding step of decoding the code based on the image of the code that has been decoded, and when decoding fails in the decoding step, the next time the image of the code is taken based on the image of the code that is the target of decoding. and the output image size of the next and subsequent code images, and when shooting the next and subsequent code images, shooting is performed with this adjusted exposure time, and the code image of the output image size is adjusted. and a control step for controlling to output a code image from the next time onwards based on the image of the code to be decoded when decoding fails in the decoding step. When adjusting the exposure time when photographing and the output image size of subsequent code images, the next and subsequent code images are photographed based on the luminance value of the code image targeted for decoding. If the length of the determined candidate exposure time is shorter than the predetermined minimum exposure time, the exposure time is adjusted to the minimum exposure time , and The method is characterized in that the output image size is adjusted to a predetermined size.
Further, the program according to the present invention causes a computer of a code reading device equipped with an imaging means for taking an image of an optically readable code to decode the code based on an image of the code taken by the imaging means. a decoding means for decoding, and when the decoding by the decoding means fails, the exposure time of the next and subsequent code images taken by the imaging means and the next and subsequent code images are determined based on the image of the code to be decoded. a control means for adjusting the output image size of the image, causing the next and subsequent code images to be photographed using the adjusted exposure time, and controlling the image to output the code image having the output image size ; The control means controls the exposure time when the imaging means takes subsequent images of the code based on the image of the code that is the target of the decoding when decoding by the decoding means fails. When adjusting the output image size of the next code image and the output image size of the next code image, the exposure that becomes a candidate when shooting the next code image is based on the luminance value of the code image that is the target of the decoding. If the determined candidate exposure time is shorter than a predetermined minimum exposure time, the exposure time is adjusted to the minimum exposure time and the output image size is set to a predetermined value. It is characterized by being adjustable to the size of.

According to the present invention, reading can be performed efficiently even in a dark place.

1 is a front view showing the overall structure of a code reading device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of a code reading device. FIG. 2 is a plan view of an imager module and an imager controller. It is a flowchart which shows the control procedure of the code reading process by a code reading device. It is a flowchart which shows the control procedure of exposure time and image size adjustment processing by a code reading device. (a) is a diagram showing the size of the entire image taken by the image sensor, (b) is a diagram showing half the size of the entire image taken by the image sensor, and (c) is a diagram showing the size of the entire image taken by the image sensor. FIG. 3 is a diagram schematically showing time allocation.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a front view showing the overall structure of a code reading device according to an embodiment of the present invention.
The code reading device (computer) 1 of this embodiment is a portable device that has a function of reading codes such as one-dimensional barcodes and two-dimensional codes.

The code reading device 1 includes a case 2 as a housing. The code reading device 1 includes, on the front side of the case 2, a trigger key 12A, various keys 12B, and a display section 14. The code reading device 1 includes a trigger key 12C on the side surface of the case 2. The code reading device 1 also includes an imager module (scanner device) 21 at the tip of the case 2 .

The trigger keys 12A and 12C are trigger keys that accept input of a command to start the code reading operation by the imager module 21. The various keys 12B include input keys for numbers, characters, etc., function keys, etc., and accept input operations for various information. The display unit 14 displays information such as menus and statuses related to input operations, and information such as statuses and decoding results when code reading operations using the imager module 21 are executed.

FIG. 2 is a block diagram showing the internal configuration of the code reading device 1. As shown in FIG.

The code reading device 1 includes a CPU (Central Processing Unit) 11 as an adjusting means, a control means, a decoding means, and a determining means, an operation section 12, a RAM (Random Access Memory) 13, a display section 14, and a storage section 15. , a communication section 16 , an imager controller 19 , an imager module 21 , a power supply section 22 , and a laser drive power supply 23 .

Each section of the code reading device 1 except for the imager module 21 and the power supply section 22 is connected to each other via a bus 24. The imager module 21 includes an image sensor (imaging means) 211, a variable focus lens 212, a focus mechanism 213 that drives the variable focus lens 212 to adjust the focus, an aimer (light emitting means) 214, and an illumination (lighting means). 215.

The CPU 11 controls each part of the code reading device 1. The CPU 11 reads various programs from the storage unit 15, loads them into the RAM 13, and executes various processes in cooperation with the programs loaded into the RAM 13.

The operation unit 12 has a key group such as various keys 12B, trigger keys 12A, 12C, etc., receives a press operation of each key in the key group, converts the operation information into an input signal, and outputs the input signal to the CPU 11.

The RAM 13 is a volatile semiconductor memory and provides the CPU 11 with a working memory space. Further, the RAM 13 is used for temporary storage of various data and for expansion when executing various programs.

The display unit 14 is composed of an LCD (Liquid Crystal Display), an EL (Electro Luminescent) display, etc., and displays various information according to display information input from the CPU 11.

The storage unit 15 is a readable and writable nonvolatile memory, for example, a flash memory. The storage unit 15 stores various programs and setting data in advance. Alternatively, the storage unit 15 may be an EEPROM (Electrically Erasable and Programmable Read Only Memory) or a hard disk. Alternatively, a ROM (Read Only Memory) may be used in a dedicated code reading device. The programs stored in the storage unit 15 include a program 15a that scans a code using the imager module 21 and decodes image data of the obtained code.

The communication unit 16 includes a communication antenna, a signal processing unit, a modulation unit, a demodulation unit, etc., and performs wireless communication with an access point. An access point is a device that relays communication. That is, the code reading device 1 uses the communication unit 16 to communicate with an external device such as a server device connected to the access point via the access point. The communication unit 16 processes a signal of transmission information in a signal processing unit, modulates it in a modulation unit, and wirelessly transmits the transmission information as a radio wave from a communication antenna to an access point. Further, the communication unit 16 receives radio waves transmitted from the access point using the communication antenna, demodulates the radio waves using the demodulation unit, processes the signals using the signal processing unit, and obtains reception information.

Furthermore, the communication unit 16 may be a wireless communication unit that wirelessly communicates with the server device via a base station using a mobile phone communication method. Further, the communication unit 16 may be a cradle on which the code reading device 1 is placed, or a wired communication unit that communicates with the server device via a communication cable.

The imager controller 19 controls the operation of each part of the imager module 21 and controls the transmission and reception of data between the imager module 21 and other parts of the code reading device 1 . The imager controller 19 is made up of a semiconductor circuit such as an ASIC (Application Specific Integrated Circuit).

The imager controller 19 synchronizes with the image data from the image sensor 211 with a frame synchronization signal synchronized with the output timing of one frame of captured image data and a line synchronization signal synchronized with the output timing of one line of image data. A clock signal is input. The imager controller 19 monitors the timing of transferring image data to the RAM 13 based on these frame synchronization signals, line synchronization signals, and clock signals. The imager controller 19 has a DMA (Direct Memory Access) transfer function that directly transfers image data input to the imager controller 19 from the image sensor 211 to the RAM 13 without going through the CPU 11.

The imager module 21 is a module that adjusts the focal position of the variable focus lens 212 to image the code of the subject. The image sensor 211 is, but is not particularly limited to, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The image sensor 211 captures (obtains) image data by photoelectrically converting a subject image incident through an optical system including a variable focus lens 212 into an electrical signal.

The image sensor 211 outputs the image data of the line specified by the image area designation signal inputted from the imager controller 19 to the imager controller 19 one line at a time as line data. The image sensor 211 also outputs a frame synchronization signal, a line synchronization signal, and a clock signal to the imager controller 19. The variable focus lens 212 is, for example, a liquid lens, and is an optical element that constitutes a part of the optical system of the imager module 21. This liquid lens has a configuration in which the focal position can be changed at high speed according to the voltage applied to the focus mechanism 213.

The focus mechanism 213 is a drive unit that adjusts the focal position of the variable focus lens 212. When the variable focus lens 212 is a liquid lens, the focus mechanism 213 is an electric circuit including an electrode for applying voltage to a predetermined portion of the liquid lens. Further, when a solid lens such as glass or plastic is used as the variable focus lens 212, a voice coil motor is used for the focus mechanism 213, for example.

The aimer 214 emits a laser light beam as a spot light (target light) that serves as an index for measuring the distance between the imager module 21 and the object code, and as a reference for aligning the imaging direction of the imager module 21 with the object direction. This is a laser diode (LD) that emits light. The illumination 215 is configured with a light source such as an LED (Light Emitting Diode), and emits irradiation light to brightly illuminate the subject and the area around it.

The power supply section 22 is composed of a secondary battery or the like, and supplies power to each section of the code reading device 1. The laser drive power supply 23 supplies power when driving the aimer 214 to emit a spot light. The laser drive power supply 23 is arranged on the main board together with the imager controller 19.

Next, the arrangement of each part of the imager module 21 will be described in detail with reference to FIG. 3.
FIG. 3 is a plan view of the imager module 21.

In the imager module 21, an optical system 212A including a variable focus lens 212 is arranged so as to be able to image the outside of the imager module 21. Further, the image sensor 211 is arranged perpendicular to the optical axis of the optical system 212A. The aimer 214 and the illumination 215 are arranged in parallel to the optical system 212A and the focus mechanism 213. The aimer 214 is arranged so that the emitted beam-like laser light is included within an angle of view that can be imaged by the imager module 21 (optical system 212A and image sensor 211) within a changeable focal length of the optical system 212A. . In this embodiment, this laser beam is emitted in a direction parallel to the optical axis of the optical system 212A. Further, the illumination 215 is arranged such that the fan-shaped light is included within the angle of view that can be photographed by the imager module 21 (optical system 212A and image sensor 211) within a focal length that can be changed by the optical system 212A. There is.

Next, the operation of the code reading device 1 will be explained with reference to FIG. FIG. 4 is a flowchart showing a control procedure for code reading processing by the code reading device 1. As shown in FIG.

The code reading process is a process of scanning a code using the imager module 21 and decoding the image data of the obtained code. In the code reading device 1, when the user presses and inputs the trigger keys 12A and 12C as a trigger, the CPU 11 executes the code reading process in cooperation with the program 15a read from the ROM 15 and expanded appropriately in the RAM 13. do.

As shown in FIG. 4, first, the CPU 11 of the code reading device 1 sends a command to the imager controller 19 to start the imager module 21 (step S1).

Next, the CPU 11 performs initial settings (step S2). Specifically, the CPU 11 sends a command to the imager controller 19 to set the exposure time E when photographing the code, which is the object, using the image sensor 211 to a predetermined initial value (exposure value of standard brightness) E0. At the same time, the output image size R when transferring (outputting) the image data of the code photographed by the image sensor 211 to the RAM 13 is set to the entire size Rfull of the image data. Further, the CPU 11 sets the number of loops L of the code reading process to an initial value (L=0).

Next, the CPU 11 increments the value of the loop count L of the code reading process by 1 (step S3).

Next, the CPU 11 sends a command to the imager controller 19 to cause the image sensor 211 to photograph the code, and causes the image data of the code sent from the image sensor 211 to the imager controller 19 to be directly transferred to the RAM 13 by DMA (step S4). . Further, in step S4, the CPU 11 sends a command to the imager controller 19 to irradiate the illumination 215 when the image sensor 211 photographs the code, so that a bright image can be photographed. Moreover, by irradiating the aimer 214 when transmitting the image data of the code, it is possible to indicate the shooting position to the user.

Next, the CPU 11 decodes the code based on the image data transferred to the RAM 13 (step S5).

Next, the CPU 11 determines whether or not the code has been successfully decoded (step S6).

If it is determined in step S6 that the code has been successfully decoded (step S6; YES), the CPU 11 displays (outputs) the decoded data on the display unit 14 (step S7), and ends the code reading process.
On the other hand, if it is determined in step S6 that the code has not been successfully decoded, that is, it has failed (step S6; NO), the CPU 11 determines whether the value of the number of loops L is greater than 3 ( Step S8).

If it is determined in step S8 that the value of the number of loops L is greater than 3 (step S8; YES), the CPU 11 displays decoding failure data (for example, character data such as "Unable to read code"). The code is displayed (output) on the section 14 (step S9), and the code reading process is ended.
On the other hand, if it is determined in step S8 that the value of the number of loops L is not greater than 3, that is, less than or equal to 3 (step S8; NO), the CPU 11 performs an exposure time/image size (output image size) adjustment process. (described later) is performed (step S10). Then, the CPU 11 returns the process to step S3 and repeats the subsequent process.

FIG. 5 is a flowchart showing a control procedure of exposure time/image size (output image size) adjustment processing by the code reading device 1. The exposure time/image size adjustment process is a process for determining the exposure time and output image size for the next and subsequent shootings by the image sensor 211.

As shown in FIG. 5, first, the CPU 11 determines an exposure time candidate E1 (step S21). Specifically, the CPU 11 derives the brightness value of the image data of the code decoded in step S5 of the code reading process described above. Then, the CPU 11 performs exposure control processing on the derived luminance value and determines an appropriate exposure time candidate E1. Note that since the exposure control process is a well-known technique, its explanation will be omitted.

Next, the CPU 11 determines whether the length of the exposure time candidate E1 is shorter than the length of the minimum exposure time Emin that can be set in the imager module 21 (step S22).

In step S22, if it is determined that the length of the exposure time candidate E1 is shorter than the length of the minimum exposure time Emin (step S22; YES), the CPU 11 sends a command to the imager controller 19 to change the output image size R. As shown in FIG. 6(a), the size of the entire image photographed by the image sensor 211 is adjusted to Rfull (step S23), and the exposure time E is adjusted to the minimum exposure time Emin (step S24), and the exposure time - Finish the image size adjustment process.

Further, in step S22, if it is determined that the length of the exposure time candidate E1 is not shorter than the length of the minimum exposure time Emin, that is, it is determined that it is greater than or equal to the length of the minimum exposure time Emin (step S22; NO), the CPU 11 , it is determined whether the length of the exposure time candidate E1 is shorter than the length of the first maximum exposure time Emax1 that can be set in the imager module 21 (step S25). Here, the first maximum exposure time Emax1 means the maximum exposure time that can be set in the imager module 21 when the output image size R is set to Rfull.

In step S25, if it is determined that the length of the exposure time candidate E1 is shorter than the length of the first maximum exposure time Emax1 (step S25; YES), the CPU 11 sends a command to the imager controller 19 to determine the output image size. R is adjusted to the size Rfull of the entire image photographed by the image sensor 211 (step S26), and the exposure time E is adjusted to the exposure time candidate E1 (step S27), thereby ending the exposure time/image size adjustment process. .

Further, in step S25, if it is determined that the length of the exposure time candidate E1 is not shorter than the length of the first maximum exposure time Emax1, that is, it is determined that it is greater than or equal to the length of the first maximum exposure time Emax1 (step S25 ; NO), the CPU 11 determines whether the length of the exposure time candidate E1 is shorter than the length of the second maximum exposure time Emax2 that can be set in the imager module 21 (step S28). Here, the second maximum exposure time Emax2 is the maximum exposure time that can be set in the imager module 21 when the output image size R is set to half the size Rfull (see FIG. 6(b)). means.

In step S28, if it is determined that the length of the exposure time candidate E1 is shorter than the length of the second maximum exposure time Emax2 (step S28; YES), the CPU 11 sends a command to the imager controller 19 to determine the output image size. As shown in FIG. 6(b), R is adjusted to the size Rhalf, which is half of Rfull (step S29), and the exposure time E is adjusted to the exposure time candidate E1 (step S27), and the exposure time and image size are adjusted. Finish the adjustment process.

Further, in step S28, if it is determined that the length of the exposure time candidate E1 is not shorter than the length of the second maximum exposure time Emax2, that is, it is determined that it is greater than or equal to the length of the second maximum exposure time Emax2 (step S28 ; NO), the CPU 11 sends a command to the imager controller 19 to adjust the output image size R to half the size Rfull (step S30), and adjust the exposure time E to the second maximum exposure time Emax2. (Step S31), the exposure time/image size adjustment process ends.

Next, one aspect of the code reading process executed in a dark place will be described with reference to FIG. 6(c). FIG. 6(c) is a diagram schematically showing the time allocation for code reading processing.

As shown in FIG. 6(c), first, in the code reading device 1, the imager module (scanner device) 21 is activated when the trigger keys 12A, 12C are pressed and input by the user, and the exposure time E is set to the initial value. The value E0 is set, and the output image size R is set to Rfull. Then, the first code reading process (loop number L=1) is performed.

In the first code reading process, the image sensor 211 photographs the code at an exposure time E0, and the image data of the photographed code is transferred to the RAM 13 at an output image size Rfull. Then, in the first code reading process, decoding fails because the brightness value of the image data transferred to the RAM 13 is low, and the above-mentioned exposure time/image size adjustment process is performed. Here, it is assumed that the exposure time E0 is adjusted to the exposure time candidate E1, and the output image size R is adjusted to Rfull as in the first code reading process. Then, the second code reading process (loop number L=2) is performed.

In the second code reading process, the image sensor 211 photographs the code at the exposure time candidate E1, and the image data of the photographed code is transferred to the RAM 13 in an output image size Rfull. Then, even in the second code reading process, decoding fails because the brightness value of the image data transferred to the RAM 13 is low, and the above-described exposure time/image size adjustment process is performed. Here, it is assumed that the exposure time candidate E1 is adjusted to the second maximum exposure time Emax2, and the output image size R is adjusted to Rhalf. Then, the code reading process is performed for the third time (the number of loops L=3).

In the third code reading process, the image sensor 211 photographs the code at the second maximum exposure time Emax2, and the image data of the photographed code is transferred to the RAM 13 in the output image size Rhalf. In other words, in the third code reading process, while the exposure time is longer, the time spent on image transfer is shorter, and the code is read in approximately the same amount of time as the first and second code reading processes. Read processing is now in progress. Then, in the third code reading process, since photography was performed with the second maximum exposure time Emax2, which is longer than the exposure time candidate E1, the brightness value of the image data transferred to the RAM 13 becomes high and decoded. succeed in

As described above, the code reading device 1 of this embodiment is a code reading device 1 that reads an optically readable code, and includes an image sensor 211 that takes an image of the code, and an image taken by the image sensor 211. Based on the code image, the exposure time E and the output image size R of the next and subsequent code images are adjusted by the image sensor 211 to capture the next and subsequent code images. At the same time, the image sensor 211 is controlled to take a picture with the adjusted exposure time E and output an image of the code with the adjusted output image size R.
According to such a configuration, even if, for example, a code is read in a dark place and the exposure time E is adjusted to be longer when photographing subsequent code images, the output image By reducing the size R, the image data transfer time can be adjusted to be shorter.
Therefore, the code can be read even in a dark place in the same amount of time as in normal times, so that the code can be read efficiently even in a dark place.

Further, when the code reading device 1 fails to decode, it adjusts the exposure time E and the output image size R based on the image of the code targeted for decoding, thereby preventing repeated decoding failures. Can be suppressed.

In addition, the code reading device 1 determines an exposure time (exposure time candidate E1) that will be a candidate when photographing the next code image based on the brightness value of the image of the code that is the target of decoding, and If the length of the exposure time as a candidate is shorter than the length of the predetermined minimum exposure time Emin, the exposure time E is adjusted to the minimum exposure time Emin, and the output image size R is set to Rfull (predetermined size). Adjust to.
According to such a configuration, the code reading accuracy can be improved and the code can be read efficiently.

Further, the code reading device 1 determines that the length of the candidate exposure time (exposure time candidate E1) is greater than or equal to the length of the minimum exposure time Emin, and is greater than the length of the predetermined first maximum exposure time Emax1. If it is short, the exposure time E is adjusted to the candidate exposure time, and the output image size R is adjusted to Rfull (predetermined size).
According to such a configuration, the code reading accuracy can be improved and the code can be read efficiently.

Further, the code reading device 1 determines that the length of the candidate exposure time (exposure time candidate E1) is greater than or equal to the length of the first maximum exposure time Emax1, and that the length of the candidate exposure time E1 is longer than the predetermined second maximum exposure time Emax2. If it is shorter than the length, the exposure time E is adjusted to the candidate exposure time, and the output image size R is adjusted to Rfull (predetermined size).
According to such a configuration, the code reading accuracy can be improved and the code can be read efficiently.

Further, if the length of the candidate exposure time (exposure time candidate E1) is equal to or longer than the second maximum exposure time Emax2, the code reading device 1 changes the exposure time E to the second maximum exposure time Emax2. At the same time, the output image size R is adjusted to Rhalf (half the predetermined size).
According to such a configuration, the code reading accuracy can be improved and the code can be read efficiently.

The code reading device 1 also includes an illumination 215 and an aimer 214, turns on the illumination 215 when causing the image sensor 211 to take an image of the code, and transfers the image of the code taken by the image sensor 211 ( Since the aimer 214 is turned on when the code is output (output), code reading accuracy can be improved even in a dark place.

Note that the present invention is not limited to the embodiments described above, and various changes are possible.
For example, in the above embodiment, the CPU 11 decodes the code based on the image data DMA-transferred to the RAM 13, but the imager controller 19 implements the decoding function on the ASIC board and uses hardware. It may also be possible to perform calculations.

Furthermore, although a liquid lens and a solid lens using glass or the like have been cited as examples of the variable focus lens in the above embodiments, the present invention is not limited to these. For example, a variable focus lens using KTN (potassium tantalate niobate, KTa _1-x Nb _x O ₃ ), which is a type of "electro-optic crystal" whose refractive index changes depending on the applied voltage, can also be used.

Further, in the above embodiment, an example is disclosed in which the storage unit 15 (for example, flash memory, EEPROM, hard disk, ROM) is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example. As other computer-readable media, it is possible to apply a portable recording medium such as a CD-ROM. Moreover, a carrier wave (carrier wave) is also applied to the present invention as a medium for providing data of the program according to the present invention via a communication line.

In addition, in the above embodiment, the code reading process ends when the code is successfully decoded, but the settings for the exposure time E and output image size R at the time of successful decoding are inherited to continuously read multiple codes. It may also be read by
In addition, specific details such as numerical values and control order shown in the above embodiments can be changed as appropriate without departing from the spirit of the present invention.

Although the embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and equivalent ranges thereof.
Below, the invention described in the claims first attached to the application of this application will be added. The claim numbers listed in the supplementary notes are as in the claims originally attached to the request for this application.

[Additional notes]
<Claim 1>
A code reading device that reads an optically readable code,
an imaging means for taking an image of the code;
Adjusting means for adjusting the exposure time when the imaging means takes subsequent images of the code and the output image size of the subsequent images of the code, based on the image of the code taken by the imaging means; ,
A control means for controlling the imaging means to take an image at the exposure time adjusted by the adjustment means and output an image of the code having the output image size when photographing the image of the code from the next time;
A code reading device comprising:
<Claim 2>
comprising a decoding means for decoding the code based on an image of the code taken by the imaging means,
2. The adjusting means adjusts the exposure time and the output image size based on the image of the code to be decoded when the decoding by the decoding means fails. Code reader as described.
<Claim 3>
comprising determining means for determining a candidate exposure time when photographing images of the code from the next time onwards, based on the luminance value of the image of the code to be decoded;
When the length of the candidate exposure time determined by the determining means is shorter than the predetermined minimum exposure time, the adjustment means adjusts the exposure time to the minimum exposure time and adjusts the output. 3. The code reading device according to claim 2, wherein the image size is adjusted to a predetermined size.
<Claim 4>
When the length of the exposure time to be the candidate is equal to or greater than the length of the minimum exposure time and shorter than the length of a predetermined first maximum exposure time, the adjustment means adjusts the exposure time to the candidate. 4. The code reading device according to claim 3, wherein the code reading device adjusts the exposure time to the predetermined size and adjusts the output image size to the predetermined size.
<Claim 5>
The adjusting means adjusts the exposure time when the candidate exposure time is equal to or greater than the first maximum exposure time and shorter than a predetermined second maximum exposure time. 5. The code reading device according to claim 4, wherein the code reading device adjusts the output image size to the candidate exposure time and adjusts the output image size to half the predetermined size.
<Claim 6>
When the length of the candidate exposure time is greater than or equal to the second maximum exposure time, the adjustment means adjusts the exposure time to the second maximum exposure time and adjusts the output image size. The code reading device according to claim 5, wherein the code reading device adjusts the size to be half the predetermined size.
<Claim 7>
lighting means for illuminating the shooting position;
a light emitting means for guiding the shooting position;
Equipped with
The control means turns on the illumination means when causing the imaging means to photograph an image of the code, and lights the light emitting means when causing the imaging means to output an image of the code photographed. The code reading device according to any one of claims 1 to 6.
<Claim 8>
A code reading device computer comprising an imaging means for taking an image of an optically readable code,
Adjusting means for adjusting the exposure time when the image capturing means shoots the next code image and the output image size of the next code image based on the image of the code captured by the image capturing means;
A control means for controlling the imaging means to perform imaging at the exposure time adjusted by the adjustment means when photographing the next code image and output the code image of the output image size;
A program characterized by functioning as

1 Code reading device 11 CPU (adjustment means, control means, decoding means, deciding means)
211 Imaging device (imaging means)
214 Aimer (light emitting means)
215 Illumination (illumination means)

Claims (7)

A code reading device that reads an optically readable code,
an imaging means for taking an image of the code;
a decoding means for decoding the code based on an image of the code taken by the imaging means;
When the decoding by the decoding means fails, the exposure time and the output image of the next and subsequent code images by the imaging means based on the image of the code to be decoded. a control means for adjusting the size of the code , and controlling the image to be taken using the adjusted exposure time when taking the next code image, and outputting the code image having the output image size ;
Equipped with
The control means is configured to determine the exposure time and subsequent shooting times of the next code image by the imaging means based on the image of the code to be decoded when the decoding by the decoding means fails. When adjusting the output image size of the code image, a candidate exposure time is determined for the subsequent shooting of the code image based on the brightness value of the code image that is the target of decoding. , if the determined candidate exposure time length is shorter than a predetermined minimum exposure time length, the exposure time is adjusted to the minimum exposure time , and the output image size is adjusted to a predetermined size. do,
A code reading device characterized by: If the length of the determined candidate exposure time is equal to or greater than the minimum exposure time and shorter than the predetermined first maximum exposure time, the control means controls the exposure time to to the candidate exposure time and adjust the output image size to the predetermined size;
The code reading device according to claim 1, characterized in that: When the length of the determined candidate exposure time is greater than or equal to the first maximum exposure time and shorter than the predetermined second maximum exposure time, the control means adjusting the exposure time to the candidate exposure time and adjusting the output image size to half the predetermined size;
The code reading device according to claim 2, characterized in that: When the length of the determined candidate exposure time is greater than or equal to the second maximum exposure time, the control means adjusts the exposure time to the second maximum exposure time and adjusting the output image size to half the predetermined size;
The code reading device according to claim 3, characterized in that: lighting means for illuminating the shooting position;
a light emitting means for guiding the shooting position;
Equipped with
The control means turns on the illumination means when causing the imaging means to take an image of the code, and turns on the light emitting means when causing the imaging means to output an image of the code taken.
The code reading device according to any one of claims 1 to 4. A code reading method performed by a code reading device that reads an optically readable code, the method comprising:
an imaging step of taking an image of the code;
a decoding step of decoding the code based on the image of the code taken in the imaging step;
If decoding fails in the decoding step, the exposure time when photographing the next code image and the output image size of the next code image are adjusted based on the code image that is the target of the decoding. a control step of causing the next code image to be captured using the adjusted exposure time and outputting the code image having the output image size;
has
In the control step, when the decoding fails in the decoding step, the exposure time of the next and subsequent code images is determined based on the code image that is the target of the decoding, and the exposure time of the next and subsequent code images. When adjusting the output image size, a candidate exposure time is determined for photographing the next code image based on the brightness value of the code image that is the target of the decoding, and this determined exposure time is determined. If the length of the exposure time as a candidate is shorter than the length of a predetermined minimum exposure time, adjusting the exposure time to the minimum exposure time and adjusting the output image size to a predetermined size;
A code reading method characterized by: A code reading device computer comprising an imaging means for taking an image of an optically readable code,
decoding means for decoding the code based on an image of the code taken by the imaging means;
When the decoding by the decoding means fails, the exposure time and the output image of the next and subsequent code images by the imaging means based on the image of the code to be decoded. control means for controlling the code size to be adjusted, and for controlling the next code image to be captured using the adjusted exposure time, and to output the code image having the output image size;
function as
The control means is configured to determine the exposure time and subsequent shooting times of the next code image by the imaging means based on the image of the code to be decoded when the decoding by the decoding means fails. When adjusting the output image size of the code image, a candidate exposure time is determined for the subsequent shooting of the code image based on the brightness value of the code image that is the target of decoding. , if the determined candidate exposure time length is shorter than a predetermined minimum exposure time length, the exposure time is adjusted to the minimum exposure time, and the output image size is adjusted to a predetermined size. ,
A program characterized by:

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