JP2002237927A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read an image with high accuracy by regulating a temperature of a light source by a cooling fan. SOLUTION: A light source 30 is configured by placing R, G, B, IR LEDs in a form of a matrix. A luminous quantity sensor 55 is fitted to a sidewall of a diffusion box 31. The luminous quantity sensor 55 senses the luminous quantity of a red light, a green light, a blue light and an IR light for every reading of each frame image. A cooling fan 45 is driven, on the basis of an output of a thermistor 50, to keep the temperature of the light source within a prescribed temperature range. A correction circuit 56 obtains a correction value, on the basis of the sensing value of each color light from the luminous quantity sensor 55. An image processing section 9 multiplies the correction value with image data for correcting the image data. Regulating the temperature of the light source 30 can suppress the effect of the luminous quantity and a spectral change accompanied by temperature fluctuations in the light source 30 for enhancing reading accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus for suppressing a change in the state of emitted light due to a change in temperature.

[0002]

2. Description of the Related Art In recent years, reflection light such as a photographic print or transmission light such as a photographic film is irradiated with irradiation light, and reflected light or transmission light from the document is received by an image sensor such as a CCD to record on the document. An image reading device that reads a printed image, performs various corrections on the obtained image data, and then records the image on a recording material such as photographic paper and displays the image on a display is practical. Has been
Such an image recording apparatus has an advantage that the operation from reading an image recorded on a document to recording an image on a recording material, displaying an image on a display, and the like can be easily performed.

[0003] In this type of image reading apparatus, a white light source such as a halogen lamp has been used as a light source for illuminating a document, but instead of red light (R), green light (G),
An apparatus using an LED light source configured by arranging a large number of LED elements that emit blue light (B) on a substrate has also been put to practical use. By using this LED light source, a filter required for a white light source is not required, and the apparatus configuration can be simplified, and conditions such as balance of each color can be easily set.

When the LED light source emits light at a constant current value, the amount of emitted light decreases when the temperature of the LED element increases, and the amount of emitted light increases when the temperature of the LED element decreases. Further, there is a characteristic that the emission spectrum also changes due to the temperature change of the LED element. For this reason, when an LED light source is used in an image reading device, the emission spectrum changes due to a change in environmental temperature or a change in temperature due to heat generation of the light source itself, so that high-quality image data cannot be obtained. is there. As a method for solving this problem, for example, an LE
An image reading apparatus for adjusting the temperature of the D light source to a constant value has been proposed by the present applicant (Japanese Patent Laid-Open No. 7-175035).

[0005]

However, when a Peltier device is used in the above-described image reading apparatus, the Peltier device itself has good cooling efficiency, but has a problem that power consumption is increased. In addition, when the LED light source is at a high temperature, the cooling efficiency of the Peltier element decreases, and the amount of heat generated by the Peltier element itself increases. Therefore, the temperature of the LED light source cannot be reduced, and the amount of light emitted by the LED light source decreases. There's a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus that efficiently adjusts the temperature of a light source and reads an image accurately.

[0007]

To achieve the above object, a light source device according to the present invention comprises a light source having a plurality of light emitting elements arranged therein, a cooling fan for blowing air toward the light source to cool the light source, A light guide member that guides light from the light source to the image document, an imaging unit that captures the image document illuminated with light from the light source through the light guide member, and drive control of the cooling fan. A fan control unit that adjusts the temperature of the light source to a certain range, and a correction unit that detects a light emission amount of the light source and corrects an output of the imaging unit based on the detected light emission amount.

A light source in which a plurality of light emitting elements are arranged; a cooling fan for blowing air toward the light source to cool the light source; a light guide member for guiding light from the light source to the image original; Imaging means for imaging the image original illuminated with light from the light source through an optical member; a fan control unit for controlling the driving of the cooling fan to adjust the temperature of the light source to a certain range; and A light amount control unit that detects a light amount and controls the light amount of the light source based on the detected light amount.

It is preferable that the fan control section includes a temperature detecting means for detecting a temperature of the light source, and controls on / off of a cooling fan based on a temperature of the light source by the temperature detecting means. Further, the image original is a photographic film on which a plurality of images are recorded, and has a film carrier for sending the image of the photographic film to a reading position, and when a temperature of a light source detected by the temperature detecting means is equal to or lower than a reference value. It is preferable that the light source be turned on during the feeding of the photographic film by the film carrier to adjust the temperature. Further, it is preferable that the temperature detecting means detects the temperature of the light source when the device itself is turned on, and when the temperature of the light source is equal to or lower than a reference value, turns on the light source to perform temperature adjustment. Further, it is preferable that the plurality of light emitting elements are LED elements that emit red light, green light, and blue light.

[0010]

FIG. 1 is a perspective view showing the appearance of a digital lab system embodying the present invention, and FIG. 2 is a schematic diagram showing the internal structure thereof. Digital laboratory system 2
Is an input unit 3 that performs image reading and image processing, a printer unit 4 that records an image based on image data on which image processing has been performed on photographic paper, and performs development processing and the like on a photosensitive material on which an image has been exposed. And a processor unit 5.

The input unit 3 includes a film scanner 8, an image processing unit 9, an external recording device 10, and the like. The film scanner 8 is for reading an image (frame) recorded on a photographic film such as a negative film or a reversal film. Images of various photographic films such as 120 or 220 size (Brownie size) can be read. Further, by using a dedicated mount carrier, it is possible to read a photographic film on a slide mount.

The image processing unit 9 is provided above the electrical unit 11. The image processing unit 9 performs image processing such as various corrections on the image data output from the image recording device 8, stores the image data at the time of pre-scan, and prints the image data as recording image data at the time of fine scan. Output to Image processing includes gray balance adjustment, gradation correction, density (brightness) adjustment, shooting light source type correction using a matrix (MTX), and image saturation adjustment (color adjustment). In addition, electronic scaling processing, dodging processing (compression / expansion of density dynamic range), sharpness (sharpening) processing, and the like are performed. For these processes, a low-pass filter, an adder, an LUT, an MTX, and the like are used. By appropriately combining these, an averaging process, an interpolation operation, and the like are performed. The image processing unit 9 receives a correction value calculated by a correction circuit 56 described later, and corrects the image data by multiplying the read image data by the correction value. Thereafter, the above-described image processing is performed.

The external recording device 10 is provided for recording image data after image processing as an image file. Examples of the external recording device 10 include a storage medium such as a memory card and a CD-ROM. The image data after the image processing is displayed on a display 1 such as a monitor.
2 can be displayed.

The printer unit 4 is provided below the input unit 3. The printer unit 4 includes a paper feed magazine 14
, An exposure unit 15 and a transport mechanism (not shown). Photosensitive material 16 pulled out of paper feed magazine 14
Is cut by a cutter unit (not shown) at a length corresponding to the print size. The photosensitive material 16 after this cutting is exposed
The image based on the image data is exposed and recorded by the exposure unit 15, and is conveyed to the processor unit 5.

The processor section 5 comprises a developing section 18, a drying section 19, and a sorter section 20. Development processing unit 1
8 is a color developing tank 22, a bleach-fixing tank 23,
Wash tanks 24 to 27 are sequentially arranged adjacent to each other, and each is filled with a replenisher. The photosensitive material 16 is developed by passing through the processing tanks 22 to 27 and the drying unit 19 under the driving force of a transport rack (not shown). Also,
The photosensitive material 16 conveyed to the drying unit 19 is sorted by the sorter unit 20.
Is discharged. The sorter unit 20 collects prints for each order.

FIG. 3 is a front view showing the structure of the optical system of the film scanner. The film scanner 8 includes a light source 30, a diffusion box 31, a transmission diffusion plate 32, and a light guide tube 33.
And an imaging unit 39 including a lens unit 37 and an area CCD 38 are provided along the optical axis.

As shown in FIG. 4, the light source 30 includes, for example, a red light (R), a green light (G), a blue light (B), and a red light on a substrate 42 formed of a material having high thermal conductivity. Outside light (I
An LED light source in which LED elements respectively emitting light of R) are arranged in a matrix is used. Light emitted from the light source 30 is emitted in a direction along the optical axis. This light source 3
0 can emit light for each color.
The surface exposure of each color light is sequentially performed by emitting 0. Reference numeral 43 denotes a driver.

A radiation fin 44 is attached to the lower surface of the substrate 42. A cooling fan 45 is attached below the radiation fins 44. The heat radiation fins 44 dissipate heat when the light source 30 emits light. The cooling fan 45 is rotated via a motor 47 according to an instruction from the system controller 46. This rotation cools the radiation fins 44,
The temperature of the light source 30 is maintained within a certain range.
The driving method of the cooling fan 45 may be continuous driving or intermittent driving. Reference numeral 48 denotes a driver for the motor 47.

The driving of the cooling fan 45 is performed in accordance with the detection value of the thermistor 50 disposed on the substrate 42 of the light source 30. The thermistor 50 detects the temperature of the light source 30 and outputs the detected value to the fan control circuit 51. The fan control circuit 51 has a preset optimum temperature range (S1
... S2) are recorded, and a comparison is made with the detection value T from the thermistor 50. For example, when the detected value T is lower than the lower limit S1, the light source 30 is energized, and when the detected value T is higher than the upper limit S2, the cooling fan 45 is turned on.
Drive.

The diffusion box 31 is formed in a cylindrical shape, and is attached so as to surround the periphery of the substrate of the light source 30. The light emitted from the light source 30 enters the diffusion box 31 without losing the light amount. This diffusion box 3
The inner peripheral surface 1 is formed with a reflection / diffusion surface having high total reflectance and diffuse reflectance of light and having substantially uniform spectral characteristics and spectral diffuse reflection characteristics.

The diffusion box 31 guides the light emitted from the light source 30 upward and emits the light toward the transmission diffusion plate 32. At this time, uneven reflection of light from the light source 30 is reduced by diffusely reflecting the light in an irregular direction by the diffuse reflection surface. This reflection / diffusion surface diffuses and reflects light without changing the relative light amount balance of red, green, and blue light emitted from the light source 30, so that the light is emitted while maintaining the light amount balance of the incident light, and reaches the reading position. A certain photographic film 53 is irradiated.

A light amount sensor 55 is attached to a side wall of the diffusion box 31. The light quantity sensor 55 receives the diffused light in the diffusion box 31 when the light source 30 emits light, and outputs the light to a correction circuit 56 described later. The light amount measurement by the light amount sensor 55 is performed for each frame image at the time of image reading.
The processing is performed for each color light of red light, green light, and blue light.

The correction circuit 56 has a look-up table memory (LUT), in which the light amount value of each color light and the correction value corresponding thereto are written. In the correction circuit 56, a corresponding correction value is obtained from the light amount value obtained from the light amount sensor 55 and is output to the image processing unit 9. The data of the light amount value and the correction value recorded in the correction circuit 56 are, for example, data obtained from an experiment or the like. Note that the correction value may be obtained from the light amount using a correction formula or the like instead of the LUT.

The transmission diffusion plate 32 is provided so as to be in contact with the upper end of the diffusion box 31 and closes the opening at the upper end of the diffusion box 31. Opal glass, LSD, or the like is used for the transmission / diffusion plate 32, and the transmission / diffusion plate 32 is disposed so that its optical center axis coincides with the optical axis. This transmission diffusion plate 3
In the light guide tube 33, the light emitted from the diffusion box 31 is diffused and transmitted, so that the diffused light spreads in an irregular direction and the light amount distribution is made uniform to some extent.
Emit light along the optical axis toward.

The light guide tube 33 is formed in a cylindrical shape having an opening at the upper end and the lower end. The cross section orthogonal to the optical axis becomes gradually smaller from the lower end toward the upper end. ing. The central axis of the light guide tube 33 is disposed so as to coincide with the optical axis, and the lower end of the light guide tube 33 has the transmission diffusion plate 32.
It is arranged so that it may be closed by. Thus, the light transmitted through the transmission / diffusion plate 32 enters the light guide tube 33 without loss of light amount.

As shown in FIG. 3, a film carrier 58 is disposed above the light source section 34. The film carrier 58 is provided with a pair of transport rollers 59 and 60, and the photographic film 53 is transported in a predetermined direction by the rotation of the pair of transport rollers 59 and 60. Incidentally, reference numeral 61
Is a transport motor.

A lens unit 37 and an area CCD 38 constituting the image pickup unit 39 are arranged at positions facing the light source unit 34 via the photographic film 56. The lens unit 37 moves in the optical axis direction to perform focus adjustment. The light transmitted through the lens unit 37 is transmitted to the area CCD 3
An image is formed on the light receiving surface 8. The area CCD 38 includes a plurality of Cs.
The CD cells are arranged in a matrix. The area CCD 38 detects the density information of the frame image of the photographic film 53 positioned at the reading position of the film carrier 8 and outputs it to the A / D converter 64 as an image signal. The A / D converter 64 converts the image signal from the area CCD 38 into a digital signal, and outputs the digital signal to the image processing unit 9 as image data.

Next, the operation of the present embodiment will be described with reference to the flowchart shown in FIG. First, the temperature near the light source 30 is detected by the thermistor 50 and output to the fan control circuit 51. In the fan control circuit 51, the detected temperature T is compared with the optimum temperature range (S1 to S2). For example, when the detected value T is smaller than the lower limit value S1, the light source 30 is energized to perform the optimal temperature range (S1 to S2).
Converge within. On the other hand, when the detected value T is larger than the upper limit value S2, the cooling fan 45 is driven to converge within the optimum temperature range (S1 to S2). On the other hand, the detection of the temperature of the light source 30 by the thermistor 50 is continued, and the fan control circuit determines whether or not the detection value T from the thermistor 50 is converged within the optimum temperature range (S1 to S2). Note that the driving of the cooling fan 45 is stopped during image reading.

The temperature of the light source is detected by the thermistor 50 also at the time of reading an image. For example, when the detected value T is out of the optimum temperature range (S1 to S2), the photographic film 53 is fed by the film carrier 58. During operation, the light source 30 emits light or the cooling fan 45 is driven to adjust the temperature of the light source 30 so as to converge within the optimum temperature range (S1 to S2).

When the value T detected by the thermistor 50 converges within the optimum temperature range (S1 to S2), an image reading signal is sent from the system controller 46. When the image reading of the frame image of the photo film 53 is started, the light amount sensor 55 detects the light emission amount of red light, green light, and blue light for each frame image, and outputs the detected value to the correction circuit 56. . In the correction circuit 56, a correction value corresponding to the detected value of each color is obtained from the LUT. This correction value is stored in the image processing unit 9
And used as a correction value for the read image data.

On the other hand, the image data read by the area CCD 38 is output to the image processing section 9. The image processing section 9 corrects the image data by multiplying the correction value from the correction circuit 56 by the image data. Various image processing is performed on the corrected image data, and the corrected image data is output to the print unit 4. Then, in the printing unit 4, the photosensitive material 16 is exposed based on the image data on which the image processing has been performed. The exposed photosensitive material 16 is transported to the processor unit 5,
Processing such as color development and bleach-fix is performed, and the photosensitive material 16
An image is formed thereon.

In the above embodiment, the light amount sensor 55 is attached to the diffusion box 31, a correction value is calculated from the detection value of the light amount sensor 55, and the light amount is adjusted by multiplying the obtained image data by the correction value. Alternatively, the light emission amount of the light source 30 may be feedback-controlled according to the output value from the light amount sensor 55. For example, when the light emission amount is equal to or more than the set value, L
When the drive current of the ED is lowered, and the light emission amount is equal to or less than the set value, L
Increase the drive current of the ED. Note that the relationship between the light emission amount and the drive current is obtained in advance by experiments or the like, and this is stored in the LUT format. As a result, accurate temperature adjustment can be performed, and image reading can be performed with a stable light emission amount.

When the image reading apparatus itself is started,
The temperature of the light source 30 is detected by the thermistor 50, and the light source 30 is caused to emit light only when the detected value T is lower than the lower limit value S1 of the optimum temperature range (S1 to S2). May be.

The temperature of the light source may be adjusted by controlling the driving of the cooling fan and controlling the light emission amount of the light source. In this case, the data of the temperature change of the light source since the light emission of the light source is stored in the fan control circuit in advance. The fan control circuit measures the time when the light source is turned on, and drives the cooling fan when a predetermined time has elapsed. At the same time, the light emission amount of the light source is controlled. Thus, the temperature of the light source is maintained at a substantially constant value. Note that the relationship between the light emission amount and the drive current and the relationship between the fan drive time and the LED light emission amount are obtained in advance by experiments or the like, and stored in the fan control circuit in the LUT format.

[0035]

As described above, according to the image reading apparatus of the present invention, the cooling fan for cooling the light source, the fan control unit for controlling the driving of the cooling fan to adjust the temperature of the light source to a certain range, and the light source And a correction unit for correcting the output of the imaging unit based on the detected light emission amount, so that the influence of a change in light amount or spectrum due to a temperature change of the light source is suppressed, and a stable light emission amount is obtained. Image reading can be performed.

Further, since the light emission amount of the light source is detected and the light amount control means for controlling the light amount of the light source based on the detected light emission amount is provided, the light emission amount of the light source is controlled according to the temperature of the light source. An image can be read with a stable light emission amount.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a digital laboratory system embodying the present invention.

FIG. 2 is a schematic diagram showing an internal configuration of a digital laboratory system.

FIG. 3 is a front view showing the configuration of the film scanner.

FIG. 4 is a perspective view illustrating a configuration of a light source unit.

FIG. 5 is a flowchart illustrating a control process of a light source unit when reading an image.

[Explanation of symbols]

 2 Digital laboratory system 8 Film scanner 30 Light source 45 Cooling fan 50 Thermistor 51 Fan control circuit 55 Light intensity sensor 56 Correction circuit

[Procedure amendment]

[Submission date] February 8, 2001 (2001.2.8)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) H04N 1/028 H04N 1/028 Z F term (reference) 2H106 AA32 AA62 AA72 AA76 AB04 AB73 AB84 5B047 AA05 AB04 BA01 BB04 BC05 BC12 BC14 BC23 CA19 CB03 DA01 DC13 5C051 AA01 BA02 DA06 DB01 DB22 DB29 DB33 DB34 DC05 DC07 DE04 DE17 DE30 EA01 FA00 5C062 AA01 AB03 AB17 AB33 AB40 AC02 AC58 AE03 AE15 BA07 5C072 AA01 BA12 CA05 CA07 CA10 CA05 AE05 UA13 VA03 XA10

Claims (6)

[Claims] 1. An image reading apparatus for reading an image on an image document, comprising: a light source having a plurality of light emitting elements arranged therein; a cooling fan for blowing air toward the light source to cool the light source; A light guide member that guides the document, an imaging unit that captures the image document illuminated with light from the light source through the light guide member, and a driving range of the cooling fan to control the temperature of the light source within a predetermined range. An image reading apparatus, comprising: a fan control unit for adjusting the light emission amount of the light source; and a correction unit for correcting an output of the imaging unit based on the detected light emission amount. 2. An image reading apparatus for reading an image on an image document, comprising: a light source having a plurality of light emitting elements arranged therein; a cooling fan for blowing air toward the light source to cool the light source; A light guide member that guides the document, an imaging unit that captures the image document illuminated with light from the light source through the light guide member, and a driving range of the cooling fan to control the temperature of the light source within a predetermined range. An image reading device, comprising: a fan control unit for adjusting the light emission amount of the light source; and a light amount control unit for controlling the light amount of the light source based on the detected light emission amount. 3. The cooling device according to claim 1, wherein the fan control unit includes a temperature detecting unit for detecting a temperature of the light source, and controls on / off of the cooling fan based on a temperature of the light source by the temperature detecting unit. The image reading device according to claim 1. 4. The image original is a photographic film on which a plurality of images are recorded, and has a film carrier for sending the image of the photographic film to a reading position, wherein a temperature of a light source detected by the temperature detecting means is lower than a reference value. 4. The image reading apparatus according to claim 3, wherein the temperature of the photographic film is adjusted by turning on the light source while the photographic film is being fed by the film carrier. 5. The temperature detecting means detects a temperature of a light source when the device itself is turned on, and turns on the light source when the temperature of the light source is equal to or lower than a reference value to perform temperature adjustment. The image reading device according to claim 3. 6. The image reading apparatus according to claim 1, wherein the plurality of light emitting elements used for the light source are LED elements that emit red light, green light, and blue light.