JP3602831B2 - Information reproduction system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is capable of optically reading so-called multimedia information including audio information such as voice and music, video information obtained from a camera or video equipment, and digital code data obtained from a personal computer or a word processor. The present invention relates to an information reproducing system that optically reads the code pattern from an information recording medium such as paper recorded as a simple two-dimensional code pattern and reproduces the original multimedia information.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various media such as a magnetic tape and an optical disk have been known as media for recording voice, music, and the like. However, even if these media are made in large quantities, the unit price is somewhat expensive, and a large space is required for storage. Furthermore, if it is necessary to hand over the recorded media to another person at a remote location, it takes time and effort to mail it or take it directly. There was also. In addition, the same applies to so-called multimedia information including video information obtained from a camera, a video device, and the like, and digital code data obtained from a personal computer, a word processor, and the like, in addition to audio information.
[0003]
To cope with such a problem, Japanese Patent Application Laid-Open No. 6-231466 discloses that multimedia information including at least one of audio information, video information, and digital code data can be transmitted by facsimile, and a large amount of multimedia information can be transmitted. A system for recording on an information recording medium such as paper in the form of a two-dimensional code pattern in which a plurality of dots as image information that can be duplicated at low cost, that is, a plurality of dots as encoded information, and a system for reproducing the same Is disclosed.
[0004]
The two-dimensional code pattern disclosed in this publication is as shown in FIG. That is, this figure corresponds to FIG. 14 in the above-mentioned publication, and shows a dot code 170 as a two-dimensional code pattern. In the data format of the dot code 170, one block 172 includes a marker 174, a block address 176, address error detection and error correction data 178, and a data area 180 in which actual data is entered. The blocks 172 are vertically and horizontally arranged two-dimensionally, and are collectively formed in the form of a dot code 170.
[0005]
FIG. 10 is equivalent to FIG. 15 of the above-mentioned publication, and is a diagram showing a configuration of a multimedia information reproducing apparatus. The information reproducing apparatus includes a detection unit 184 for reading the dot code from the sheet 182 on which the dot code 170 is printed, a scan conversion unit 186 for recognizing the image data supplied from the detection unit 184 as a dot code, and normalizing the image data. Binarization processing section 188 for converting multi-valued data into binary, demodulation section 190, adjustment section 192 for adjusting a data string, data error correction section 194 for correcting a reading error and a data error at the time of reproduction, and data having respective attributes. A data separation unit 196 for separating data according to the attribute, a decompression processing unit for data compression processing according to each attribute, a display unit or a reproduction unit, or another input device.
[0006]
In the detection unit 184, the dot code 170 on the sheet 182 is illuminated by the light source 198, and the reflected light is transmitted through the imaging optical system 200 such as a lens and the spatial filter 202 for removing moire and the like. The light information is detected as an image signal by an imaging unit 204 such as a CCD or CMD that converts the light information into an electric signal, and is amplified by a preamplifier 206 and output. The light source 198, the imaging optical system 200, the spatial filter 202, the imaging unit 204, and the preamplifier 206 are configured in an external light shielding unit 208 for preventing disturbance to external light. Then, the image signal amplified by the preamplifier 206 is converted into digital information by the A / D converter 210 and supplied to the scan converter 186 at the next stage.
[0007]
The imaging unit 204 is controlled by the imaging unit control unit 212. For example, when an interline transfer type CCD is used as the imaging unit 204, the imaging unit control unit 212 uses the V blank signal for vertical synchronization and the information charge for resetting information charges as control signals of the imaging unit 204. Image sensor reset pulse signal, charge transfer gate pulse signal for sending charges accumulated in two-dimensionally arranged charge transfer accumulation units to a plurality of vertical shift registers, horizontal shift for transferring charges in the horizontal direction and outputting them outside A horizontal charge transfer CLK signal which is a transfer clock signal of the register, a vertical charge transfer pulse signal for transferring the plurality of vertical shift register charges in the vertical direction and sending the charges to the horizontal shift register are output.
[0008]
Then, the imaging unit control unit 212 supplies the light source with a light emitting cell control pulse for setting the light emission timing of the light source 198 in accordance with this timing.
[0009]
The image data is read between the V blank of this one field and the V blank. The light source 198 performs pulse lighting instead of continuous lighting, and performs subsequent pulse lighting while synchronizing in units of fields. In this case, the timing is controlled such that exposure is performed during the V blanking period, that is, while no image charges are being output, so that clock noise during pulse lighting does not enter the signal output. That is, since the light emitting cell control pulse is a very thin digital clock pulse generated instantaneously and gives a large power to the light source, it is necessary to prevent noise caused by the light from entering the analog image signal. It is necessary, and as a measure for this, the light source is pulsed during the V blanking period. By doing so, the S / N is improved. In addition, the pulse lighting means that the light emission time is shortened, and thus has a great effect of eliminating the influence of blurring due to the fluctuation and movement of the manual scanning. Thus, high-speed scanning can be performed.
[0010]
Further, even when the reproducing apparatus is tilted and disturbance such as external light enters for some reason in spite of the presence of the external light shielding section 208, the V-block is set to minimize the S / N deterioration. Immediately before the light source 198 emits light during the ranking period, an image sensor reset pulse is output once to reset the image signal, light emission is performed immediately after that, and reading is performed immediately thereafter.
[0011]
Next, the scan conversion unit 186 will be described. The scan conversion unit 186 is a unit that recognizes image data supplied from the detection unit 184 as a dot code and performs normalization. As a method for this, first, the image data from the detection unit 184 is stored in the image memory 214, read out therefrom once, and sent to the marker detection unit 216. The marker detector 216 detects a marker for each block. Then, the data array direction detection unit 218 detects the rotation or tilt and the data array direction using the marker. The address control unit 220 reads out the image data from the image memory 214 based on the result so as to correct the image data and supplies it to the interpolation circuit 222. At this time, lens aberration information is read from the memory 224 for correcting distortion of the lens in the imaging optical system 200 of the detection unit 184, and the lens is also corrected. Then, the interpolation circuit 222 performs an interpolation process on the image data to convert the image data into an original dot code pattern.
[0012]
The output of the interpolation circuit 222 is provided to a binarization processing unit 188. Basically, the dot code 170 is a pattern of white and black, that is, binary information, and is therefore binarized by the binarization processing unit 188. At this time, binarization is adaptively performed by the threshold determination circuit 226 while determining the threshold in consideration of the influence of disturbance, the influence of signal amplitude, and the like.
[0013]
Since modulation is performed at the time of recording, the data is demodulated by the demodulation unit 190 first, and then data is input to the data string adjustment unit 192.
[0014]
In the data string adjusting unit 192, first, the block address of the above-described two-dimensional block is detected by the block address detecting unit 228, and thereafter, the block address error is detected and corrected by the block address error detecting and correcting unit 230. , The address control unit 232 stores the data in the data memory unit 234 in block units. By storing data in units of block addresses in this way, data can be stored without waste even when data is lost or entered halfway.
[0015]
After that, the data read from the data memory unit 234 is subjected to error correction by the data error correction unit 194. The output of the error correction unit 194 is branched into two, one of which is sent to a personal computer, a word processor, an electronic notebook, etc. as digital data via the I / F 236. The other is supplied to the data separation unit 196, where it is divided into images, handwritten characters and graphs, characters and line drawings, and sounds (two types, that is, a sound as it is and a voice synthesized).
[0016]
The image is equivalent to a natural image and is a multi-valued image. In this case, a decompression process corresponding to, for example, JPEG at the time of compression is performed by the decompression processing unit 238, and the data interpolation circuit 240 interpolates data that cannot be corrected.
[0017]
For binary image information such as handwritten characters and graphs, the decompression processing unit 242 performs decompression processing on MR / MH / MMR and the like performed by compression, and the data interpolation circuit 244 cannot correct errors. The interpolation of the data is performed.
[0018]
Characters and line drawings are converted to another display pattern via a PDL (page description language) processing unit 246. Note that, in this case, if the line drawing and the character are subjected to the code compression processing after being coded, the decompression processing unit 248 performs the corresponding decompression (Huffman, Jibrempel, etc.) processing, and then The data is supplied to the PDL processing unit 246.
[0019]
The outputs of the data interpolation circuits 240 and 244 and the PDL processing unit 246 are combined or selected by a combining or switching circuit 250, converted into analog signals by a D / A converter 252, and then converted to a CRT (television monitor) or FMD. (A face mounted display) or the like. Note that the FMD is a spectacle-type monitor (handy monitor) for wearing on the face, and is effective when, for example, virtual reality is used or when a large screen is viewed in a small place.
[0020]
For audio information, a decompression process is performed on an ADPCM or the like by a decompression processing unit 256, and further, data that cannot be error-corrected is interpolated by a data interpolation circuit 258. Alternatively, in the case of speech synthesis, the speech synthesis unit 260 receives the speech synthesis code and actually synthesizes the speech from the code and outputs the synthesized speech. In this case, when the code itself is compressed, as in the case of the characters and line drawings, the decompression processing unit 262 performs decompression processing such as Huffman or Jibrempel, and then performs speech synthesis.
[0021]
The outputs of the data interpolation circuit 258 and the voice synthesis unit 260 are synthesized or selected by a synthesis or switching circuit 264, converted into an analog signal by a D / A conversion unit 266, and then output to a speaker, headphones, or other similar audio output device. 268.
[0022]
In addition, characters and line drawings are output directly from the data separation unit 196 to the page printer and plotter 270, and characters and the like are printed on paper as word processing characters, or line drawings and the like are output as plotters and the like. You can also.
[0023]
Of course, the image can be printed not only by the CRT or FMD but also by a video printer or the like, and the image can be photographed.
[0024]
In such an information reproducing apparatus, for example, the detection unit 184 and the scan conversion unit 186 are configured to be housed in a pen-shaped housing, and this is used as a reading unit that optically reads the dot code 170 on the sheet 182. The reading unit is held by hand, and the code is read by manually scanning the sheet 182 along the recorded dot code 170.
[0025]
[Problems to be solved by the invention]
Incidentally, a binarization processing unit 188 that adaptively binarizes while determining a threshold value by the threshold value determination circuit 226 as described above is disclosed in, for example, JP-A-59-61383. Various binarization circuits are known. This binarization circuit obtains the maximum value and the minimum value of the previous frame from the digital data converted by the A / D converter, calculates a threshold value from the maximum value and the minimum value, and uses the calculated threshold value as the threshold value of the current frame. It is to do.
[0026]
In the reproduction system of the dot code 170 as described above, since the distance from the sheet 182 to the imaging unit 204 is short, it is greatly affected by the regular reflection, and the video signal obtained from the imaging unit 204 includes noise. Would. Also, when there is a pixel defect in the imaging unit 204, it becomes noise. Due to such noise, in the configuration of the binarization circuit as disclosed in the above publication, the maximum value and the minimum value cannot be obtained accurately, and as a result, the binarization at an appropriate threshold cannot be performed. Would.
[0027]
The present invention has been made in view of the above points, and has as its object to provide an information reproduction system that reproduces information by appropriately performing binarization.
[0028]
[Means for Solving the Problems]
In order to achieve the above object, an information reproducing system according to the present invention comprises:
From a recording medium on which information is recorded as an optically readable code pattern,In an information reproducing system that optically reads the code pattern to reproduce the information,
A light source for illuminating the code pattern;
An imaging unit that captures a code pattern illuminated by the light source and outputs a corresponding image signal,
A system control unit that controls an illumination light amount of the light source based on an image signal from the imaging unit,
A threshold detection unit that calculates a threshold for binarizing the image signal from the imaging unit based on the image signal;
Binarization means for binarizing the image signal from the imaging unit with a threshold calculated by the threshold detection unit,
With
The threshold detection unit changes the calculated threshold based on a change in the amount of illumination of the light source by the system control unit.Is configured as follows,
The light source is configured to perform pulse lighting in synchronization with a predetermined unit of the image signal,
The system control unit is configured to control the illumination light amount of the light source for each of the predetermined units by changing the width or height of the pulse,
The threshold detection unit is configured to calculate the threshold for each of the predetermined units,
The binarization unit is configured to binarize the image signal for each of the predetermined units,
The code pattern is composed of a plurality of blocks, each of which includes a data area in which a plurality of dots are two-dimensionally arranged corresponding to the content of information to be reproduced, and a reading reference point of the data area. When a dot code that has a marker and a block address arranged at a predetermined position with respect to the data area to be determined and that can be read by manual scanning,
The width of the pulse as one exposure period changed by the system control unit is such that the dots can be detected when the dot code is manually scanned at a predetermined maximum scanning speed that does not cause block omission. Controlled within range,
It is characterized by the following.
[0029]
That is, according to the information reproducing system of the present invention, the system controller controls the amount of light of the light source that illuminates the code pattern based on the image signal from the imaging unit, and controls the image based on the image signal from the imaging unit. A threshold detecting unit that calculates a threshold for binarizing the signal changes the calculated threshold based on a change in the illumination light amount of the light source by the system control unit.
[0030]
Therefore, it is possible to reproduce the information by accurately binarizing the image signal immediately after the light amount control operation.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
FIG. 1A is a diagram illustrating a configuration of a binarization circuit according to the first embodiment of the present invention that can be used as the binarization unit 188 and the threshold determination unit 226 illustrated in FIG.
[0033]
An image signal input from the input terminal 10 is supplied to a period extracting unit 12 that extracts a specific period in an image. The cycle extracting unit 12 may extract, for example, the cycle of the marker 174 that is periodically arranged in the dot code as shown in FIG. That is, when the pattern of the marker 174 and the data dot 174A as shown at the top of the figure is captured, the image actually obtained from the imaging unit is as shown in the middle of the figure. In order to extract only the period of the marker 174 from such an image signal, the period extracting unit 12 is configured as a low-pass filter. As a result, as shown at the bottom of the figure, a fine pattern such as the data dot 174A is removed, and a signal in which the amplitude of only the white portion where the dot code is not recorded and the portion of the marker 174 are stored is obtained. Can be
[0034]
When a dot code having the same size as the data dot 174A and having a pattern matching dot composed of a predetermined position and pattern is used, the period extracting unit 12 The period of the matching dot may be extracted. In this case, the cycle extraction unit 12 is configured as a bandpass filter that extracts the cycle of the pattern matching code.
[0035]
FIGS. 1C and 1D are diagrams respectively showing the characteristics of the filter constituting the period extracting unit 12 when extracting the marker 174 and when extracting the pattern matching dot (data dot 174A). These examples show the case where the frequency of the data of one pixel of the CCD constituting the imaging unit is 10 MHz, the minimum dot size of the data dot 174A is 3 pixels, and the dot size of the marker 174 is 21 pixels.
[0036]
The image signal output from the cycle extracting unit 12 is supplied to the maximum value detecting unit 16 and the minimum value detecting unit 18 via the detection gate 14. Here, the detection gate 14 divides the output signal of the cycle extraction unit 12 into predetermined units, for example, fields or frames, and the following description will be made assuming that it is divided into fields. Therefore, the maximum value detection unit 16 and the minimum value detection unit 18 detect the maximum value and the minimum value of the image signal within the range of one field.
[0037]
The detected maximum value and minimum value are supplied to the threshold detection unit 20. The threshold value detected by the threshold value detection unit 20 is held in the data holding unit 22 for the predetermined unit, that is, for one field. Note that the threshold detection unit 20 calculates the threshold th, for example, by using the maximum value max and the minimum value min by the following equation (1).
[0038]
th = min + k (max−min) (1)
Here, k is an internal division ratio for determining a threshold value, and may be a fixed value, or may be set adaptively based on the result of binarizing a dot whose size is known in advance. good.
[0039]
On the other hand, the image signal input to the input terminal 10 is also supplied to the signal processing circuit 24. The signal processing circuit 24 is, for example, a waveform equalizing circuit, and functions as a filter for raising a dot cycle.
[0040]
Then, the output of the signal processing circuit 24 and the output of the data holding unit 22 are compared by a comparator 26, and the result is output from an output terminal 28 as a binary signal.
[0041]
The system control unit 30 controls each of the above units, and always monitors the maximum value max and the minimum value min detected by the maximum value detection unit 16 and the minimum value detection unit 18 to perform error detection and the like.
[0042]
The signal processing circuit 24 has a configuration as shown in FIG. That is, the input signal is supplied to the adder 24C via the two delay circuits 24A and 24B, and is also directly supplied to the adder 24C. Here, the data is delayed by one dot by the two delay circuits 24A and 24B. Accordingly, the adder 24C adds both sides of the period for one dot. The result of the addition is supplied to the subtractor 24E after being multiplied by the coefficient from the system control unit 30 by the multiplier 24D. The other input of the subtractor 24E is provided with a result obtained by multiplying the output of the delay circuit 24A, that is, the middle cycle of one dot by the coefficient from the system control unit 30 by the multiplier 24F. The difference between these multiplication results is multiplied by a coefficient from the system control unit 30 in the multiplier 24G, and the result is output to the comparator 26 as an output of the signal processing circuit 24. .
[0043]
In practice, instead of giving each coefficient from the system control unit 30, a configuration in which one coefficient is finally multiplied by hardware may be adopted.
[0044]
As described above, in the first embodiment, since a specific period in a code, for example, a period of a marker is extracted, unnecessary noise can be removed. That is, erroneous detection due to noise can be prevented, so that an appropriate threshold can be obtained.
[0045]
The direction of delay in the delay circuits 24A and 24B is the same one-dimensional direction as the modulation direction of the dot code. That is, the reading direction of the image memory 214 and the modulation direction in FIG. 10 are the same. Therefore, effective waveform equalization can be performed with such a simple circuit configuration. Further, since the dot cycle is emphasized by the waveform equalizing circuit, the amplitude of the signal of the dot cycle is amplified, and the binarization can be surely performed.
[0046]
Since the image signal input to the input terminal 10 is read out from the image memory 214 of the scan conversion unit in accordance with the data arrangement direction, the description has been made on the assumption that the readout direction, the modulation direction, and the delay direction are the same. When the image data is directly input from the imaging unit 204, the scanning direction of the CCD pixels of the imaging unit 204 is the same as the modulation direction and the delay direction.
[0047]
Next, a second embodiment of the present invention will be described.
[0048]
FIG. 3A shows the configuration, and the same components as those in FIG. 1A of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.
[0049]
That is, in the second embodiment, the LED 34 is connected to the system control unit 30 via the LED driver 32. That is, the system control unit 30 basically controls the amount of light of the LED 34 to be variable according to the maximum value detected by the maximum value detection unit 16. Here, the LED 34 corresponds to the light source 198 in the configuration of FIG. 10 and illuminates the dot code 170 recorded on the sheet 182 surface.
[0050]
As shown in FIG. 3B, the LED driver 32 includes a transistor and a resistor, and a driving pulse is applied from the system control unit 30. In this case, the system control unit 30 inputs the maximum value detected by the maximum value detection unit 16 to the saturation detection comparator 30A and the dark detection comparator 30B as shown in FIG. A comparison is made whether the output is saturated or dark. Then, the width or height (amplitude) of the drive pulse generated by the pulse generator 30C is changed according to the comparison result.
[0051]
For example, if the amount of light currently being emitted is dark, and it is not saturated when it is in a state that does not provide the most illuminance, it can still be brightened, so increase the amount of light Conversely, if the saturation is reached when the maximum exposure, that is, the exposure in the bright state, is reached, the pulse can still be darkened. Change the width.
[0052]
Here, since only two detection comparators are used, two-stage light amount control is performed. However, by increasing the number of detection comparators, the light amount can be discretely controlled by that number. Becomes possible. As described above, by controlling the light amount discretely based on the maximum value, the dynamic range of the signal can be secured, and the binarization can be surely performed.
[0053]
Next, the light amount control will be described with reference to the timing charts of FIGS.
[0054]
In these figures, the waveform shown at the top is a video signal supplied to the input terminal 10. Here, the row period is a vertical blanking period.
[0055]
The second waveform from the top is a signal detection gate pulse provided from the system control unit 30 for opening and closing the detection gate 14. This is a signal for determining a frame in which part in the video signal is to be detected, and becomes high for each field. The detection gate 14 supplies the output signal of the cycle detection unit 12 to the maximum value / minimum value detection circuits 16 and 18 at the subsequent stage only during the high period.
[0056]
The third waveform shown below is a threshold value calculation signal for controlling the threshold value calculation timing in the threshold value detection unit 20, and the calculation is performed in the high state. The system control unit 30 sets this signal to a high state at a timing during the vertical blanking period.
[0057]
The fourth waveform is a sample-and-hold (S / H) pulse for controlling the timing of holding the threshold given from the system control unit 30 to the data holding unit 22. The data holding unit 22 samples the result of the threshold operation when the S / H pulse becomes high, and holds the result during the low period, that is, the period of one field.
[0058]
The fifth waveform is a reset (RES) pulse to the threshold detector 20. This is because if the threshold calculation result in the threshold detection unit 20 is held in the data holding unit 22, the threshold calculation result does not need to be held in the threshold detection unit 20, and is reset here. I have.
[0059]
The sixth shows a threshold calculation result calculated by the threshold detection unit 20 and stored in the data storage unit 22. For example, there are three types of states: within a preset regulation, below the regulation (low), and above the regulation (high).
[0060]
The seventh shows the state of the setting coefficient L. The setting coefficient L is as follows. That is, in the present embodiment, the threshold value th is calculated by the following equation (2) in the threshold value detecting section 20.
[0061]
th = {min + k (max-min)} L (2)
The setting coefficient L is normally “1” when the light amount of the LED 34 is not changed, and is set to “1” or more or “1” or less only in the field in which the light amount of the LED 34 is changed. .
[0062]
Eighth is the irradiation light amount of the LED 34, where low means darkening and high means brightening.
[0063]
The last ninth waveform indicates the exposure timing in the imaging unit (not shown).
[0064]
First, a case where the light amount is insufficient will be described with reference to FIG.
[0065]
The threshold value calculation in the threshold value detection unit 20 is performed during a vertical blanking period between the field shown as the previous field and the field shown as the first field. This threshold value calculation is based on the maximum value and the maximum value obtained from the video signal of the previous field. This is performed according to the above equation (2) based on the minimum value. If the threshold calculation result obtained in this way is a value equal to or smaller than the specified value, this means that the image is considerably dark, and if image capturing is continued with this light amount, appropriate binarization will not be performed. . Therefore, control is performed to increase the irradiation light amount of the LED 34. In the present embodiment, since the irradiation is performed in units of fields, the light amount is kept low in the first field, and the irradiation is performed before the start of the second field. Increase the light intensity.
[0066]
However, the threshold calculation performed during the vertical blanking period between the first field and the second field is based on the video signal of the first field exposed during the vertical blanking period between the previous field and the first field. It is. On the other hand, the signal that is actually binarized by the comparator 26 is the signal that was exposed during the vertical blanking period between the first field and the second field, that is, the second field that was exposed when the irradiation light amount was high Video signal. That is, although the video signal is high, the threshold value remains as it is, and appropriate binarization is not performed. Therefore, for the second field, the value of the setting coefficient L is set to “1” or more. By doing so, it becomes possible to detect the shortage of the light quantity and to capture the data of the field in which the irradiation light quantity has changed from low to high.
[0067]
The value of the setting coefficient L is set to “1” or more only for the field in which the light amount is changed from low to high. Here, the value of the setting coefficient L equal to or more than “1” is set to a value such as “1.15” if the irradiation light amount is increased by 15%, for example. Of course, it is necessary to set this value to an appropriate value corresponding to the applied device configuration.
[0068]
Then, since the light amount does not change in the next second to third fields, the value of the setting coefficient L is returned to the original “1”.
[0069]
FIG. 5 is a timing chart showing a case in which the amount of light is excessive, and is basically the same as FIG.
[0070]
In this example, when the illumination of the LED 34 is dimmed because it is too bright, the control is performed such that the setting coefficient L of the second field is set to “1” or less, and the value is returned to “1” when entering the third field.
[0071]
As described above, the light amount of the LED 34 can be changed by changing the amplitude or width of the pulse generated by the pulse generator 30C. However, the darkness does not mean that the width, that is, the light emission time, can be prolonged.
[0072]
That is, when an image is picked up by manually scanning the dot code, the positional relationship between each dot of the dot code and the image pickup unit changes every moment during the one exposure period. For example, the state shown in FIG. 6A as shown in FIG. 6A is changed to the state shown in FIG. 6A during one exposure period. Think. Here, a, b, c, d, e, f, and g indicate pixels of, for example, a CCD of the imaging unit.
[0073]
First, when the state changes from the state (a) to the state (a) during one exposure period, the state is a stationary state. In this case, the integrated output of each pixel is as shown in FIG. As shown in the first waveform, pixels a and b and f and g have values (amplitude) corresponding to black, pixels d and e have values (amplitude) corresponding to white, and pixel c has an intermediate value (amplitude). )become. That is, the dot cycle is stored in the pixels a to e.
[0074]
Next, when the state changes from the state (a) to the state (b), as shown by the middle waveform in FIG. , And the pixel b has moved from the center of the black dot to the center of the white portion, so that the integrated output is an intermediate value between black and white,. Therefore, as in the case of the stationary state, since the period from the pixel a to the pixel e is almost one period, the period is preserved. Therefore, even if the manual scanning is performed such that the state moves from the state (a) to the state (b) during one exposure period, the amplitude is reduced but the period is preserved, so that the detection is performed. There is a possibility.
[0075]
However, if the pixel moves from the state (a) to the state (c) during one exposure period, all the pixels similarly pass between black and white. As shown in the last waveform, the integrated output potential has a flat value of the intermediate value. That is, if the movement amount becomes too large within one exposure period, the movement becomes blurred and cannot be detected.
[0076]
Accordingly, the length of one exposure period, that is, the light emission time of the LED 34, is controlled within a range where dots can be detected when manual scanning is performed at the maximum scanning speed that does not cause block omission specified in advance by the apparatus. It is necessary to. That is, as shown in FIG. 6B, as the moving amount increases, the amplitude decreases, the contrast ratio is lost, the noise is buried in noise, and the detection becomes impossible. It is necessary to specify the light emission time of the LED 34 within the allowable movement amount range. It has been experimentally confirmed that the maximum allowable movement amount range is about 3/4 of one dot.
[0077]
Next, a third embodiment of the present invention will be described.
[0078]
FIG. 7 is a diagram showing the configuration, and the same components as those in FIG. 1A of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.
[0079]
That is, in the third embodiment, the system control unit 30 is provided with the error detection circuit 30D. The error detection circuit 30D captures the maximum value and the minimum value of the video signal detected by the maximum value detection unit 16 and the minimum value detection unit 18 and detects whether or not it reads the dot code correctly. If it is found that the code has not been read correctly, an error signal is sent to the threshold detection unit 20 or the fact that the dot code is not scanned indicates that the multimedia information reproduced by the subsequent processing of the binarization circuit is used. This is a circuit for displaying on a monitor 36 for output or outputting an error sound to notify the occurrence of an error.
[0080]
For example, if the minimum value is larger than expected, it means that a pure white object has been scanned, and in that case, a certain fixed threshold is output from the threshold detector 20 and the monitor 36 Causes the display to indicate that this is not a dot code.
[0081]
Conversely, when the maximum value is smaller than the specified value, it means that a black portion is scanned, or that the light emitted from the light source is not returned, that is, the imaging unit does not image the medium. This is the case. Even in such a case, similarly, it is displayed that the dot code is not scanned, or a certain fixed threshold is forcibly output from the threshold detecting unit 20.
[0082]
That is, even if only white or black is imaged, the maximum value and the minimum value always exist in the image, and if the threshold value is calculated by using the threshold value detection unit 20, a white image is taken, for example. Nevertheless, the irregularities on the surface of the medium are output as a binary signal, and a fixed threshold value is output in order to eliminate such a case.
[0083]
Next, a fourth embodiment of the present invention will be described.
[0084]
FIG. 8A shows the configuration, and the same components as those in FIG. 1A of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.
[0085]
That is, in the fourth embodiment, a non-linear processing unit 38 is configured before the period extracting unit 12 and the signal processing circuit 24.
[0086]
The non-linear processing unit 38 does not always use the black color of the video signal when actually picking up a dot code recorded with ink on the paper surface of the medium, and the non-linear processing unit 38 shown in FIG. Since the base is floating as described above, a process for suppressing the base to a certain black level is performed as shown in FIG. As a result, the contrast ratio between white and black is increased, and binarization is facilitated.
[0087]
Note that the binarization circuits described in the first to fourth embodiments can be constituted by analog circuits or digital processing circuits. It is needless to say that it can be appropriately selected according to.
[0088]
Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the present invention. Here, the gist of the present invention is summarized as follows.
[0089]
(1) reading means for optically scanning a dot code from a recording medium on which multimedia information including at least one of audio information, image information and digital code data is recorded as an optically readable dot code And a binarizing circuit for binarizing an image signal corresponding to the dot code read by the reading means, and performing predetermined processing on the binarized data from the binarizing circuit to obtain the original The binarization circuit in the information reproducing system, comprising: processing means for restoring multimedia information; and output means for reproducing and outputting each piece of multimedia information based on an output signal from the processing means.
A filter for extracting a specific cycle in the dot code in the image signal corresponding to the dot code read by the reading unit,
Maximum value and minimum value detection means for detecting a maximum value and a minimum value in a predetermined unit of a specific cycle extracted by the filter,
Threshold calculation means for calculating a binarization threshold from the maximum value and the minimum value detected by the maximum value and the minimum value detection means,
A binarizing unit that binarizes an image signal corresponding to the dot code read by the reading unit with a threshold calculated by the threshold calculating unit;
A binarization circuit, comprising:
[0090]
That is, since the specific period in the dot code is extracted, erroneous detection due to noise can be prevented, and a reliable threshold value can be obtained.
[0091]
(2) A signal for receiving an image signal corresponding to the dot code read by the reading unit and performing a one-dimensional waveform equalization process in the same direction as the modulation direction of the dot code, as a signal for binarizing the signal. The binarization circuit according to (1), further comprising a signal processing circuit for supplying the binarization means.
[0092]
That is, since the scanning direction and the modulation direction of the two-dimensional image sensor of the reading unit are the same, small-sized and effective waveform equalization can be performed by one-dimensional waveform equalization processing.
[0093]
(3) The dot code has a data code corresponding to the content of the multimedia information to be reproduced and a marker arranged at a predetermined position with respect to the data code for determining a reading reference point thereof. And
The binarization circuit according to (1), wherein the filter is a filter for extracting a period of the marker.
[0094]
That is, since the marker cycle is extracted, unnecessary noise can be removed, and a reliable threshold value can be obtained.
[0095]
(4) The binarization circuit according to (2), wherein the waveform equalization processing in the signal processing circuit emphasizes a dot cycle of the data code.
[0096]
That is, the amplitude of the dot period signal is amplified, and the binarization can be performed reliably.
[0097]
(5) The apparatus further comprises a light quantity control means for discretely controlling the light quantity of the light source provided in the reading means based on the maximum value detected by the maximum value and the minimum value detection means. The binarization circuit according to (1).
[0098]
That is, the dynamic range of the signal can be secured, and the binarization can be reliably performed.
[0099]
(6) The binarization circuit according to (5), wherein the light amount control means controls the light amount in two stages.
[0100]
That is, the circuit configuration is simplified, and the dynamic range can be secured with a small-scale circuit.
[0101]
(7) The binarization circuit according to (5), further including a unit that changes a threshold value calculated by the threshold value calculation unit based on a change in light amount by the light amount control unit.
[0102]
That is, the input signal immediately after the light amount control operation can be accurately binarized.
[0103]
(8) The binarization circuit according to (1), further comprising a unit that detects an error based on a relationship between the maximum value and the minimum value detected by the maximum value and the minimum value detection unit.
[0104]
That is, it is possible to detect that the obtained input signal is not the one of the two-dimensional data to be detected (all black, all white, or the middle thereof). Further, it is possible to detect whether the controlled light amount is appropriate.
[0105]
(9) The image forming apparatus according to (1), further comprising a unit that is provided at a stage preceding the filter and that performs a non-linear process on an image signal corresponding to the dot code read by the reading unit. Value conversion circuit.
[0106]
That is, the contrast is improved by compressing the black level, and the binarization can be surely performed.
[0107]
(10) The binarization circuit according to (1), wherein the threshold value calculation means performs a threshold value calculation during a vertical blanking period.
[0108]
That is, it is possible to complete the calculation for obtaining the threshold necessary for binarization during the blanking period of the scanning operation for reproducing the two-dimensional data.
[0109]
(11) The light quantity control means includes an exposure time control means for controlling a light quantity by an exposure time,
The exposure time control means defines the exposure control time range within the maximum allowable movement amount during the exposure in consideration of the movement blur at the maximum scanning speed. Value conversion circuit.
[0110]
That is, since the moving blur is reduced and the influence of the blur is eliminated, the binarization can be surely performed.
[0111]
【The invention's effect】
As described in detail above, according to the present invention, it is possible to provide an information reproduction system that reproduces information by appropriately performing binarization.
[Brief description of the drawings]
FIG. 1A is a block diagram of a binarization circuit according to a first embodiment, and FIGS. 1B to 1D are diagrams for explaining the operation of a period extracting unit in FIG. 1A; FIG.
2A is a block diagram of a signal processing circuit in FIG. 1A, and FIG. 2B is a diagram for explaining a delay direction.
FIG. 3A is a block diagram of a binarization circuit according to a second embodiment, FIG. 3B is a circuit diagram of an LED driver in FIG. 3A, and FIG. 3C is a diagram of FIG. FIG. 2 is a block diagram of a system control unit.
FIG. 4 is a timing chart for explaining an example of field-by-field control of the amount of light when there is insufficient light.
FIG. 5 is a timing chart for explaining an example of field-based control of the amount of light in the case of over-light.
FIG. 6A is a diagram illustrating various positional relationships between each dot and an image sensor when imaging is performed while scanning a dot code, and FIG. 6B is a diagram illustrating a relationship between a scanning speed and an imaging output signal. FIG.
FIG. 7 is a block diagram of a binarizing circuit according to a third embodiment;
FIG. 8A is a block diagram of a binarizing circuit according to a fourth embodiment, and FIGS. 8B and 8C are diagrams for explaining the operation of the nonlinear processing unit in FIG. FIG.
FIG. 9 is a diagram illustrating a format of a dot code.
FIG. 10 is a diagram showing a configuration of a conventional multimedia information reproducing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Input terminal, 12 ... Period extraction part, 14 ... Detection gate, 16 ... Maximum value detection part, 18 ... Minimum value detection part, 20 ... Threshold value detection part, 22 ... Data holding part, 24 ... Signal processing circuit, 24A, 24B delay circuit, 24C adder, 24D, 24F, 24G multiplier, 24E subtractor, 26 comparator, 28 output terminal, 30 system control unit, 30A saturation detection comparator, 30B dark detection Comparator, 30C pulse generator, 30D error detection circuit, 32 LED driver, 34 LED, 36 monitor, 38 nonlinear processing unit.

Claims (2)

From a recording medium on which information is recorded as an optically readable code pattern, in the information reproduction system for reproducing the information by reading the code pattern optically,
A light source for illuminating the code pattern;
An imaging unit that captures a code pattern illuminated by the light source and outputs a corresponding image signal,
A system control unit that controls an illumination light amount of the light source based on an image signal from the imaging unit,
A threshold detection unit that calculates a threshold for binarizing the image signal from the imaging unit based on the image signal;
Binarization means for binarizing the image signal from the imaging unit with a threshold calculated by the threshold detection unit,
With
The threshold detection unit is configured to change the calculated threshold based on a change in the amount of illumination of the light source by the system control unit ,
The light source is configured to perform pulse lighting in synchronization with a predetermined unit of the image signal,
The system control unit is configured to control the illumination light amount of the light source for each of the predetermined units by changing the width or height of the pulse,
The threshold detection unit is configured to calculate the threshold for each of the predetermined units,
The binarization unit is configured to binarize the image signal for each of the predetermined units,
The code pattern is composed of a plurality of blocks, each of which includes a data area in which a plurality of dots are two-dimensionally arranged corresponding to the content of information to be reproduced, and a reading reference point of the data area. When a dot code that has a marker and a block address arranged at a predetermined position with respect to the data area to be determined and that can be read by manual scanning,
The width of the pulse as one exposure period changed by the system control unit is such that the dots can be detected when the dot code is manually scanned at a predetermined maximum scanning speed that does not cause block omission. Controlled within range,
An information reproduction system characterized by the above. 2. The information reproducing system according to claim 1, wherein the threshold value detection unit calculates the threshold value during a vertical blanking period of the image signal.

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