JP2003044825A - Device and method for counting sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet counting device capable of obtaining quantity of light necessary for imaging without exposing sheets to light. SOLUTION: A sheet piled body 11 is obtained by laminating a plurality of sheets provided with optical transparency and photosensitivity. The sheet piled body 11 has transmission that periodically changes along the direction of sheet lamination. This sheet counting device 30 consists of a stroboscopic device 31, an imaging device 32 and a controlling part 38. The stroboscopic device 31 is provided with a filter that cuts light of a wavelength to which sheets are easily exposed. When the stroboscopic device 31 emits light, transmitted light that transits the sheet piled body 11 generates a light and darkness pattern on the side face of the sheet piled body 11. The imaging device 32 images the pattern. The controlling part 38 counts the number of sheets on the basis of obtained imaged data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet counting apparatus and method for counting the number of sheets in a sheet stack in which a plurality of sheets are stacked.

[0002]

2. Description of the Related Art For example, as described in Japanese Unexamined Patent Publication No. 8-315102, a sheet counting device for optically counting the number of sheets in a sheet stack in which a plurality of light-transmitting sheets are stacked is known. Are known.

This sheet counting device comprises a light projector which irradiates the side surface of the sheet stack with light and a light receiver which receives the light reflected by the side surface. Since the sheet stack has a difference in transmittance and reflectance between the sheet and the vicinity of the boundary between the sheets, the transmittance and the reflectance periodically change along the sheet stacking direction. Therefore, the amount of reflected light reflected by the side surface also periodically changes along the sheet stacking direction, and the number of sheets is counted based on this change. An LED (Light Emitting Diode) is used as the light projector.

[0004]

However, the LED
(Light Emitting Diode) and LD (Laser Diode) have insufficient light quantity as a light source for imaging. Further, when counting a sheet having photosensitivity such as an X-ray film, it is necessary to irradiate with light having a wavelength at which the sheet is not easily exposed to light. Infrared light is used as light having a wavelength that makes it difficult for the sheet to be exposed to light, and a video camera (vidicon camera) equipped with a vidicon (image pickup tube) is used as an image pickup means using this light.
According to this, since infrared light is used as irradiation light, exposure of the X-ray film can be prevented. However, since this vidicon camera has low resolution, it cannot be used for counting thin sheets having a thickness of less than 1 mm.

In order to solve the above-mentioned problems, the present invention provides a sheet counting apparatus and method which can obtain a light amount necessary for image pickup without exposing a sheet having light transparency and photosensitivity. With the goal.

[0006]

In order to achieve the above object, a sheet counting device of the present invention comprises a plurality of light-transmissive and photo-sensitive sheets laminated so that the transmittance is periodic along the sheet laminating direction. In a sheet counting device that optically counts the number of sheets in a sheet stack that changes to, a strobe device that irradiates light toward the first side surface of the sheet stack, and the strobe device and the sheet stack body. A filter that is disposed between and that cuts light having a wavelength that the sheet easily sensitizes among lights emitted by the strobe device,
The first light is transmitted by the light transmitted through the sheet assembly.
Of the light and dark pattern generated on the second side surface different from the side surface of the image pickup lens, an image pickup means arranged at the image forming position of the image pickup lens for picking up the light and dark pattern, and obtained by this image pickup means. And counting means for counting the number of sheets based on the captured image data.

The irradiation time of the strobe device is preferably adjustable. It is preferable to use a telecentric lens as the photographing lens.

In the sheet counting method of the present invention, a plurality of sheets having a light transmitting property and a photosensitive property are laminated, and the number of sheets in the sheet stack in which the transmittance periodically changes along the sheet laminating direction is optically determined. In the sheet counting method for counting, the strobe device irradiates light toward the first side surface of the sheet stack, and the light source emits light by a filter arranged between the light source and the sheet stack. Of the light, light having a wavelength that the sheet easily sensitizes is cut, and a bright and dark pattern generated on the second side surface different from the first side surface by the transmitted light that has passed through the sheet assembly is imaged by the imaging unit. Then, the number of sheets is counted based on the image pickup data obtained by the image pickup means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a sheet assembly 11 is formed by laminating a plurality of light-transmitting sheets 12. As the sheet 12, for example, an X-ray film having a thickness T0 of about 0.2 mm is used, and the sheet aggregate 11 is formed by stacking about 150 sheets 12 of this sheet. As shown in FIG. 1C, the X-ray film is composed of, for example, a transparent film base 14 and an emulsion layer 16 formed by coating a photographic emulsion on both surfaces of the transparent film base 14.

The emulsion layer 16 has a light transmittance lower than that of the film base 14. In addition, at the boundary of each sheet 12,
Although a slight gap is generated, since there are many portions where the sheets 12 are in contact with each other, the transmittance of this portion is also lower than the light transmittance of the film base 14. Therefore, the transmittance near the boundary of each sheet 12 including the emulsion layer 16 is lower than the transmittance at the central portion in the thickness direction of each sheet 12 where the film base 14 is located. Since the sheet stack 11 is composed of a plurality of sheets 12, the transmittance of the sheet stack 11 in the sheet stacking direction changes periodically. This change in transmittance has a substantially constant cycle, and the cycle is the sheet 1
2 corresponds to a thickness T0.

Therefore, the side surface 11 of the sheet assembly 11 is
When light is radiated toward a in parallel with the sheet surface, a bright and dark pattern is generated on the side surface 11a opposite to the side surface 11a according to the periodic change of the transmittance.

As shown in FIG. 2, when the light-dark pattern is picked up by the image pickup means, the light-dark level of the obtained pixel data changes periodically in the sheet stacking direction. The number of sheets 12 in the sheet stack 11 can be counted by counting the number of pieces of pixel data having a brightness of a predetermined level L1 or higher among these pieces of pixel data.

FIG. 3 is a graph showing the spectral characteristics of the X-ray film. As can be seen from this graph, the X-ray film has a high absorptivity even in the visible light region (about 400 nm to 800 nm), and reaches the lowest absorptivity (0.1) in the near infrared region having a wavelength of 900 nm. Therefore, in order to perform counting without exposing the X-ray film to light, it is necessary to use light having a wavelength of at least 900 nm. Further, in order to secure the amount of light necessary for imaging, a light source having a higher light intensity than that of an LED or the like is required.

As shown in FIG. 4, the sheet counting device 30
Includes a strobe device 31, an image pickup device 32, and a control unit 38 for controlling them. Reference numeral 39 indicates an optical axis.
An imaging device used for counting X-ray films has a resolution capable of discriminating the light and dark patterns described above, and
It is necessary to have sensitivity to light having a wavelength of 900 nm or more. Therefore, a CCD camera is used as the image pickup device 32.

As shown in FIG. 5, the image pickup device 32 includes a photographing lens 41 for forming the light and dark pattern, and about 500.
The CCD line sensor 42 has a 0-bit image sensor. A telecentric lens is used as the taking lens 41. A telecentric lens is a lens that passes only light that is close to parallel rays. With this telecentric lens, a clear image can be obtained as compared with an ordinary lens. Especially when an ordinary lens is used, the peripheral portion of the image is greatly affected by the distortion of the peripheral portion of the lens, and the blur of the image is more severe than that of the central portion. By using a telecentric lens, blurring in the peripheral portion is reduced. This allows
More accurate counting becomes possible.

The CCD line sensor 42 is a taking lens 4
It is arranged at the image forming position of 1. A signal captured by the CCD line sensor 42 is converted into digital data by an A / D converter (not shown), and the converted captured image data is sent to the control unit 38.

As shown in FIG. 6, the strobe device 31 includes
Xenon discharge tube 44, reflector 46, strobe circuit 4
It consists of 7. The strobe device 31 emits light based on a trigger signal issued from the control unit 38 to the strobe circuit 47. FIG. 7 shows the spectral output characteristics of the xenon discharge tube 44. The strobe device 31 has a higher light intensity than an LED and emits light having a wavelength of 900 nm or more.

However, as can be seen from FIG. 7, the xenon discharge tube 44 also emits light having a wavelength of about 900 nm or less. Therefore, the filter 4 is placed on the front surface of the xenon discharge tube 44.
8 is provided, and the wavelength of 9 is provided by this filter 48.
It cuts off light in the vicinity of 00 nm and below. The graph of FIG. 8 shows the spectral transmittance characteristics of the filter 48. The filter 48 has such a characteristic that the transmittance increases near the wavelength of 900 nm and the transmittance almost reaches the peak near the wavelength of 940 nm.

As shown in FIG. 3, the X-ray film has the lowest absorptance for light having a wavelength of about 900 nm or more, but since the absorptance is not "0", the light irradiation time is short. Moderate. On the other hand, in order to capture an image, it is necessary to secure a certain amount of light. Therefore, the irradiation amount of the light source is determined in consideration of the spectral sensitivity of the X-ray film (count object) and the securing of the light amount necessary for imaging.

However, since some X-ray films have various spectral sensitivities, it is necessary to use filters having different spectral transmittance characteristics according to the spectral sensitivities. Then, when the filter is changed, the irradiation amount of the strobe device 31 must be adjusted accordingly. Therefore, the irradiation time of the strobe device 31 can be adjusted so that the irradiation amount can be easily adjusted according to the spectral sensitivity. The control of the irradiation time is performed by the control unit 38.

[0021]

[Table 1]

Combinations A to K shown in Table 1 are examples of combinations of filters having different wavelengths at which the transmittance peaks and the irradiation time of the strobe device. In this way, the irradiation time of the strobe device 31 is adjusted in accordance with the characteristics of the spectral transmittance of the filter in order to secure the irradiation amount necessary for taking an image without exposing the X-ray film.
In the filter 48 of this example, the wavelength at which the transmittance peaks is about 940 nm, so the irradiation time of the strobe device 31 is
It will be 0.05 sec.

As a light source whose irradiation amount can be adjusted, a combination of a halogen lamp and a liquid crystal shutter or a mechanical shutter can be considered in addition to the strobe device. However, as shown in Table 1, the irradiation time is adjusted on the order of 0.1 sec or less. Since the response speed of the existing liquid crystal shutter or mechanical shutter is slow, the irradiation time of 0.1 sec or less cannot be adjusted. Therefore, in this example, a strobe is used as the light source.

The control unit 38 includes a VRAM 51 and a counting unit 52.
It has and. The VRAM 51 stores the image pickup data input from the image pickup device 32. The counting unit 52 counts the number of sheets based on the imaged data.

The operation of the above configuration will be described below. When the sheet stack 11 is set in the sheet counting device 30 and a counting instruction is given, the strobe device 31 emits light and the sheet stack 11 is irradiated with light. Of the light emitted by the strobe device 31, light having a wavelength of around 900 nm or less is
Since the sheet is cut by the filter 48, the sheet 12 is not exposed to light.

The image pickup device 32 picks up an image of the bright and dark patterns formed on the side surface 11a of the sheet stack 11. Since a telecentric lens is used as the taking lens 41, a clear image can be obtained. The captured image data is sent from the CCD line sensor 42 to the control unit 38, and the control unit 38
Counts the number of sheets 12 based on the imaged data.

In the above example, an X-ray film was used as an example of the sheet. However, the sheet is not limited to the X-ray film, but can be applied to other sheets having light transmittance and photosensitivity. As described above, even when counting sheets other than the X-ray film, since the strobe device capable of adjusting the irradiation time is used, it is possible to easily adjust the light amount according to the spectral sensitivity of the sheet.

In the above example, the light transmitter and the light receiver are arranged so that light is transmitted from one of the two adjacent side surfaces of the side surface of the sheet assembly to the other. When the height is high, the light projector and the light receiver may be arranged so that light is transmitted from one of the two opposite side surfaces of the side surface of the sheet assembly to the other.

[0029]

As described in detail above, the present invention is
A plurality of light-transmissive and photo-sensitive sheets are laminated, and light is emitted toward the first side surface of the sheet assembly whose transmittance changes periodically along the sheet stacking direction. Of the emitted light, light having a wavelength that the sheet easily sensitizes is cut, and a bright and dark pattern generated on the second side surface different from the first side surface by the transmitted light transmitted through the sheet assembly is imaged. Imaged by
Since the number of sheets is counted based on the image pickup data obtained by the image pickup means, it is possible to obtain a sufficient amount of light for image pickup without exposing the sheets to light.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a sheet stack.

FIG. 2 is an explanatory diagram showing a periodic change in the light-dark level in the sheet stacking direction when the side surface of the sheet stack is imaged.

FIG. 3 is a graph showing a spectral absorption characteristic of an X-ray film.

FIG. 4 is a configuration diagram of a sheet counting device.

FIG. 5 is a configuration diagram of an imaging device.

FIG. 6 is a configuration diagram of a strobe device.

FIG. 7 is a graph showing a spectral output characteristic of a xenon discharge tube.

FIG. 8 is a graph showing a spectral transmittance characteristic of a filter.

[Explanation of symbols]

11 sheet stack 12 sheets 30 sheet counting device 31 Strobe device 32 Imaging device 41 Shooting lens 42 CCD line sensor 44 xenon discharge tube 48 filters

Claims (4)

[Claims] 1. A sheet counting device for optically counting the number of sheets in a sheet stack in which a plurality of sheets having light transmissivity and photosensitivity are laminated and the transmittance periodically changes along the sheet laminating direction, A strobe device that irradiates light toward the first side surface of the sheet stack, and the sheet that is disposed between the strobe device and the sheet stack and that is emitted by the strobe device, is exposed to the sheet. A filter that cuts off light of an easy wavelength, a photographing lens that forms a bright and dark pattern on a second side surface different from the first side surface by the transmitted light that has passed through the sheet assembly, and a combination of the photographing lens. The image pickup means is arranged at the image position and picks up the light and dark pattern, and the counting means counts the number of sheets based on the image pickup data obtained by the image pickup means. Sheet counting apparatus according to claim. 2. The sheet counting device according to claim 1, wherein the irradiation time of the strobe device is adjustable. 3. The sheet counting device according to claim 1, wherein a telecentric lens is used as the taking lens. 4. A sheet counting method for optically counting the number of sheets in a sheet stack in which a plurality of sheets having a light-transmitting property and a photosensitive property are stacked and the transmittance periodically changes along the sheet stacking direction. Of the light emitted from the light source, the sheet emits light from the strobe device toward the first side surface of the sheet stack, and a filter arranged between the light source and the sheet stack is Light having a wavelength which is easily exposed to light is cut, and a bright and dark pattern generated on the second side surface different from the first side surface by the transmitted light transmitted through the sheet assembly is imaged by the image pickup means and obtained by this image pickup means. A sheet counting method, wherein the number of sheets is counted based on the captured image data.