JPH11112733A - Light quantity adjusting mechanism of image reading device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate enhancement of a mirror change-over angle precision in a mirror angle change-over mechanism by reflecting the light from a light source by an original and varying the irradiation position of the light through the use of a light quantity adjusting mechanism which compares the detected light quantity, judges it and adjust the light quantity. SOLUTION: The light source 3 consists of a cold cathode-ray tube, etc., having an aperture angle α in a radial direction and both ends are held by a holding mechanism to freely rotate. A rotation adjusting mechanism 8 is provided with a motor 1 and a gear mechanism 12 and the irradiation position of the light as against the original is varied when the motor 11 is driving-controlled. The light source 3 is irradiated, the reflected light from the original is detected, it is compared with a previously set target light quantity, the rotation adjusting mechanism 8 is driven at the time of noncoincidence and the irradiation position of the light from the light source 3 is varied so as to obtain coincidence. The number of parts is reduced and the mechanism is simplified since it is not necessary to prepare a mirror for permitting the light of the light source to be made incident to an exposure quantity detecting equipment and the mirror of an original scanning system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount adjusting mechanism of an image reading apparatus suitable for use in a facsimile or a copying machine, and a light amount adjusting method thereof.

[0002]

2. Description of the Related Art Generally, an image reading apparatus includes a platen made of glass or the like on which a document as an object to be scanned is placed;
A light source for irradiating the document from below the platen, a reflector for amplifying the amount of light from the light source, and a C for photoelectrically converting reflected light from the document located near the reflector.
A CD, a lens for changing the size of the original image to the size of the light receiving surface of the CCD, and a mirror between the lens and the original table for taking reflected light from the original into the CCD It has been known.

The light source of such an image reading device includes:
A cold cathode tube or an electrodeless tube has been frequently used because of its advantages such as a large amount of light, a small amount of heat generation, and a small size.

These have an irradiation port which opens at a predetermined angle (aperture angle) in the radial direction of the light source, and a hot melt or the like is provided in a holder in the image reading apparatus so as to extend in the main scanning direction of reading the original. It is fixed by an adhesive.

Further, such an image reading apparatus includes:
For the purpose of always obtaining a stable image, a light amount adjusting mechanism for controlling the light amount of the light source is included.

Conventionally, as a light amount adjusting mechanism of this type of image reading apparatus, there is one disclosed in Japanese Patent Application Laid-Open No. Sho 59-49532 as "a light amount adjusting device for an exposure lamp in an electronic copying machine".

In an electronic copying machine or the like in which reflected light from a document is incident on a photosensitive drum, the angle of a mirror is temporarily switched before reading a document, and reflected light from the document is detected by a photodetector. The light amount of the light source is adjusted by comparing the detected light amount with a preset light amount.

Further, as a light amount adjusting mechanism of this type of image reading apparatus, there is a light amount adjusting mechanism disclosed in Japanese Patent Application Laid-Open No. 61-175634 as an "optimum exposure amount control device for a copying machine".

In this method, light emitted from a light source is reflected by a mirror, and reflected light from the mirror is received by an exposure amount detector.
The light amount of the light source is adjusted by comparing the amount of light received by the exposure amount detector with the reference light amount and controlling the voltage applied to the light source.

In such an image reading apparatus, with the recent increase in speed of image reading and high definition image quality, it is required that the amount of light from the light source taken into the CCD be more stable. .

[0011]

However, in the former (Japanese Patent Application Laid-Open No. 59-49532), the mirror angle when scanning the original by the mirror angle switching mechanism and the case where the irradiation light is incident on the photodetector. However, in order to always obtain stable light quantity comparison accuracy, it is necessary to increase the mirror switching angle accuracy, and there is a problem that the entire mechanism becomes complicated.

On the other hand, the latter (JP-A-61-175634)
), A mirror for allowing the light from the light source to be incident on the exposure detector is required separately from the mirror of the original scanning system, so that the number of parts increases and the cost increases. there were.

Further, in such a light amount adjusting mechanism, since the light source is fixed to the holder with an adhesive, there is a problem that the aperture angle of the light source varies, and the light amount required for image reading varies.

The present invention has been made in view of such circumstances, and it is possible to simplify the entire mechanism and reduce the cost, and to prevent the occurrence of variations in the amount of light required for image reading. An object of the present invention is to provide a light amount adjusting mechanism of an image reading device and a light amount adjusting method thereof.

In order to achieve the above object, a light amount adjusting mechanism of the image reading apparatus according to the first aspect of the present invention reflects light emitted from a light source on an original, detects reflected light from the original, and A light amount adjusting mechanism for comparing the detected light amount and the reference light amount to adjust the irradiation light amount on the document, wherein the light source is configured by a light source for changing the irradiation position of the irradiation light on the document. Therefore, in each image reading apparatus, the irradiation position of the irradiation light on the document is changed to obtain a predetermined detected light amount.

According to a second aspect of the present invention, in the light amount adjusting mechanism of the image reading apparatus according to the first aspect, a rotation adjusting mechanism for applying a rotating force to the light source is provided. Therefore, the change of the irradiation position of the irradiation light to the document is performed by rotating the light source by the rotation adjusting mechanism.

The third aspect of the present invention is the first or second aspect.
In the light amount adjusting mechanism of the image reading apparatus described above, the image reading apparatus includes a reflecting plate that receives the irradiation light from the light source and reflects the light on the original. Therefore, the irradiation light from the light source directly reaches the document and also reaches the document via the reflection plate.

According to a fourth aspect of the present invention, in the light amount adjusting mechanism of the image reading apparatus according to the third aspect, a driving mechanism is provided which is driven in conjunction with the rotation adjusting mechanism and applies the driving force to the reflecting plate. . Therefore, the light source is rotated by the rotation adjusting mechanism, and the reflecting plate is driven by the driving mechanism.

According to a fifth aspect of the present invention, in the light amount adjusting mechanism of the image reading apparatus according to any one of the first to fourth aspects, a light detector for detecting reflected light from the document is provided. Therefore, the detection of the reflected light from the original is performed by the photodetector.

According to a sixth aspect of the present invention, in the light amount adjusting mechanism of the image reading apparatus according to any one of the first to fifth aspects, a controller having a determination unit for comparing and determining the detected light amount and the reference light amount is provided. There is a configuration. Therefore, the determination unit of the controller performs a comparison determination between the detected light amount as the reflected light amount from the document and the preset reference light amount.

According to a seventh aspect of the present invention, in the light amount adjusting mechanism of the image reading apparatus according to the sixth aspect, the image reading apparatus further includes a display unit for displaying a result of the determination by the determination unit.
Therefore, the result after the comparison between the detected light amount and the reference light amount is displayed on the display unit.

According to an eighth aspect of the invention (a method for adjusting the light amount of the image reading apparatus), the irradiation light from the light source is reflected by the original, the reflected light from the original is detected, and the detected light amount is compared with the reference light amount. In this method, the irradiation light amount is adjusted by varying the irradiation position of irradiation light from a light source.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a perspective view showing a light amount adjusting mechanism of the image reading apparatus according to the first embodiment of the present invention,
FIG. 2 is a side view for explaining light amount adjustment by the light amount adjustment mechanism of the image reading apparatus according to the first embodiment of the present invention. In FIG. 1, the light amount adjusting mechanism of the image reading apparatus denoted by reference numeral 1 includes a document table 2, a light source 3, a reflecting plate 4, a photoelectric conversion element 5, a lens 6, a mirror 7, and a rotation adjusting mechanism 8.

The original table 2 is made of glass or the like through which light emitted from the light source 3 passes, and an original (not shown) as an object to be scanned is placed on the upper side.

The light source 3 is composed of, for example, a cold cathode tube or an electrodeless tube having an aperture angle (elevation angle) α in the radial direction, and both ends are rotatably held by respective holding mechanisms (only one is shown), and the whole is entirely. It is arranged below the document table 2. As a result, as shown in FIG. 2, a document (not shown) above the document table 2 is irradiated from below the document table 2 at an irradiation angle θ.

The holding mechanism 9 is composed of holder elements 9a and 9b which approach and move away from each other via the light source 3 by rotating the fixing screw 10, and are disposed near the document table 2.

Thus, when the fixing screw 10 is rotated in the forward direction (tightening direction), each holder element 9 is rotated.
The light source 3 is fixed to the holding mechanism 9 by a and 9b approaching each other. On the other hand, when the fixing screw 10 is rotated in the negative direction (direction for releasing the tightening), the holder elements 9a and 9b are separated from each other, and the light source 3 is rotatably held by the holding mechanism 9.

The reflection plate 4 is located below the document table 2 and is disposed near the light source 3. Thereby, the irradiation light (reflected light) from the light source 3 to the original (not shown) is amplified.

Although the reflection plate 4 is shown as being of a fixed type, it may be of a movable type. In this case, a driving force is applied to the reflecting plate 4 by a driving mechanism (not shown) driven in conjunction with the rotation adjusting mechanism 8.

The photoelectric conversion element 5 comprises a CCD for photoelectrically converting reflected light from a document (not shown), is disposed downstream of the lens 6, and is connected to a photodetector (not shown). Have been. Thereby, an optical signal from a document (not shown) is converted into an electric signal.

The photodetector (not shown) and the rotation adjusting mechanism 8 are provided with a judging section (not shown) for comparing the detected light quantity with a reference light quantity (target light quantity) and a judging section (not shown). ) Is connected to a controller (not shown) having a display unit (not shown) for displaying the determination result in (1). In this case, a comparison result is also displayed in the determination unit (not shown).

The lens 6 is disposed between the photoelectric conversion element 5 and the mirror 7. As a result, the size of the original image is scaled to the size of the light receiving surface of the photoelectric conversion element 5. Mirror 7
Is located upstream of the lens 6 and is disposed below the document table 2. As a result, reflected light from a document (not shown) is taken into the photoelectric conversion element 5.

The rotation adjusting mechanism 8 has a motor 11 and a gear mechanism 12. Thereby, when a controller (not shown) drives and controls the motor 11, this driving force (rotational force) is applied to the light source 3 via the gear mechanism 12, and
The irradiation position of irradiation light on a document (not shown) is changed.

Next, a light amount adjusting method of the image reading apparatus according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart for explaining a light amount adjusting method of the image reading apparatus according to the first embodiment of the present invention. First, the light source 3 is turned on, and this lighting light (irradiation light) is reflected by a document (not shown), and reflected light from the document (not shown) is detected. The detection of the reflected light is continued until the exposure amount is stabilized (step S1).

Next, the amount of reflected light (detected light) from a document (not shown) is sampled (step S2).
The detected light amount is compared with a preset target light amount (step S3). At this time, the comparison result is displayed on a display unit (not shown).

When the detected light amount and the target light amount match (step S4), the light source 3 is turned off. Step S4
In the case where the detected light amount does not match the target light amount, the rotation adjusting mechanism 8 is driven to change the irradiation position of the irradiation light from the light source 3, and the process returns to step S2. At this time, the determination result (coincidence / mismatch between the detected light amount and the target light amount) is displayed on a display unit (not shown). In this way, the light amount of the image reading device can be adjusted.

Therefore, in this embodiment, since the predetermined detection light amount can be obtained by changing the irradiation position of the irradiation light to the original, it is not necessary to increase the mirror switching angle accuracy of the mirror angle switching mechanism as in the conventional case.

Further, in the present embodiment, the fact that the irradiation position of the irradiation light on the document is changed to obtain a predetermined detected light amount means that the mirror for making the irradiation light from the light source enter the exposure amount detector as in the prior art. There is no need to prepare a mirror for the document scanning system, so that the number of components can be reduced.

Further, in the present embodiment, since the irradiation light amount is adjusted by changing the irradiation position of the irradiation light from the light source 3, it is possible to prevent the variation of the aperture angle of the light source 3.

In this embodiment, the case where the light source is a cold cathode tube or an electrodeless tube has been described.
The present invention is not limited to this, and the same effects as those of the embodiment can be obtained with a fluorescent tube or a halogen lamp with a housing.

Further, in the present embodiment, an example in which the light amount is adjusted by driving the rotation adjusting mechanism 8 to rotate the light source 3 has been described. However, the present invention is not limited to this, and the light source 3 is not limited thereto. The light amount can be adjusted by performing a manual rotation operation.

[0042]

As described above, according to the present invention, the irradiation light from the light source is reflected by the original, the reflected light from the original is detected, and the detected light amount is compared with the reference light amount to determine the original. In the light amount adjusting mechanism for adjusting the irradiation light amount to the light source, since the light source comprises a light source that changes the irradiation position of the irradiation light to the original, in each image reading device,
By changing the irradiation position of the irradiation light on the document, a predetermined detected light amount can be obtained. Therefore, there is no need to increase the mirror switching angle accuracy of the mirror angle switching mechanism as in the related art, so that the entire mechanism can be simplified.

Also, the fact that a predetermined detected light amount can be obtained by changing the irradiation position of the irradiation light on the original is because the mirror for making the irradiation light of the light source enter the exposure amount detector and the original scanning system as in the conventional art. Since there is no need to prepare a mirror, the number of parts can be reduced, and the cost can be reduced.

Further, since the irradiation light amount is adjusted by changing the irradiation position of the irradiation light from the light source, it is possible to prevent the variation in the aperture angle of the light source, and to prevent the variation in the light amount required for image reading. It can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a light amount adjusting mechanism of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view for explaining light amount adjustment by a light amount adjustment mechanism of the image reading apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating a light amount adjusting method of the image reading apparatus according to the first embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light amount adjusting mechanism 2 platen 3 light source 4 reflector 5 photoelectric conversion element 6 lens 7 mirror 8 rotation adjusting mechanism 9 holding mechanism

Claims (8)

[Claims] 1. A light amount adjusting mechanism for reflecting light emitted from a light source on a document, detecting reflected light from the document, comparing the detected light amount with a reference light amount, and adjusting the irradiated light amount on the document. Wherein the light source comprises a light source that changes an irradiation position of irradiation light on the document. 2. A light amount adjusting mechanism for an image reading apparatus according to claim 1, further comprising a rotation adjusting mechanism for applying a rotating force to said light source. 3. The light amount adjusting mechanism for an image reading apparatus according to claim 1, further comprising a reflector that receives irradiation light from the light source and reflects the light on the document. 4. The light amount adjusting mechanism of the image reading apparatus according to claim 3, further comprising a driving mechanism that is driven in conjunction with the rotation adjusting mechanism and applies the driving force to the reflection plate. 5. A light amount adjusting mechanism for an image reading apparatus according to claim 1, further comprising a photodetector for detecting reflected light from said document. 6. The light amount adjusting mechanism for an image reading apparatus according to claim 1, further comprising a controller having a determination unit for comparing and determining the detected light amount and the reference light amount. 7. A light amount adjusting mechanism for an image reading apparatus according to claim 6, further comprising a display unit for displaying a result of the judgment by said judgment unit. 8. A light amount adjusting method for reflecting light emitted from a light source on a document, detecting reflected light from the document, comparing the detected light amount with a reference light amount, and adjusting the irradiated light amount on the document. And adjusting the irradiation light amount by changing the irradiation position of the irradiation light from the light source.