JPH0614556Y2 - Projection image reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a projection image reading apparatus used in a copying apparatus capable of copying a transmissive original such as a slide film in addition to an ordinary reflective original.

(Prior Art) Conventionally, a projection image reading apparatus used in a copying apparatus capable of copying a projected original image by transparently enlarging a transparent original such as a slide film in addition to copying a normal reflective original document is shown in FIG. There is something like. In the figure, reference numeral 100 denotes a projection device as a projection unit for a transparent original, and the projection device 10
Inside 0, a light source 111, a lens 112, a slide film 113, and a projection lens 114 are mounted. The projection light from the projection device 100 is reflected by the reflection mirror 102 and is imaged on the upper surface of the original platen glass 104. 103
Is a Fresnel lens arranged on the platen glass 104 in order to give directivity to a light beam having a spread in the projection direction. Reference numeral 106 denotes an imaging lens provided inside the main body 108 of the projection image reading apparatus. When a gradient index optical transmission body is used for the imaging lens 106, it is necessary to convert the projection light into a parallel light flux. Then, the projection image projected on the platen glass 104 is formed by the imaging lens 1 as in the case of a normal reflection original.
An image is formed on the line sensor 107 by 06. The image information read by the line sensor 107 is transferred to and printed by a printer unit such as a laser beam printer.

(Problems to be Solved by the Invention) In such a conventional example, the light amount distribution on the platen glass 104 when a transparent original is projected is determined by the lens 1
Although it depends on the efficiency of the light source 12 and the aperture efficiency of the projection lens 114, it generally depends largely on the light distribution characteristics of the light source 114. 4 and 5 show typical halogen lamps (for example J
C-24V150W), and FIG. 4 is a graph showing the light distribution characteristic in the lamp width direction, and FIG. 5 is a graph showing the light distribution characteristic in the lamp length direction. Is off-axis (for example, 4
The luminous flux of 5 °) is about 75% in terms of light quantity,
A further problem is that there are several peaks in the light distribution characteristic in the lamp width direction (Fig. 4), and the difference between the peak (mountain) and the valley (valley) is about 10%. The uneven light amount is more noticeable when an image is output than the gentle change in the light amount as shown in FIG. 5, and it is impossible to correct the light amount with an attenuator (a filter having a central transmittance lower than that of the peripheral portion). There is a problem.

As described above, it is considered that the difference in the light distribution characteristic depending on the direction of the lamp is related to the direction of the winding wire (usually a tungsten wire) forming the lamp filament. As shown in FIG. 6, if the axial direction of the winding (coil) of the filament F is A'and the direction B'perpendicular to the axial direction, it is the direction of A'that is inconvenient for the image as described above. . That is, it is considered that since a gap when the filament F is wound is formed in the axial direction of the winding of the filament F, unevenness in light distribution easily occurs due to sparseness and denseness of the filament F in the light emitting direction.

In view of the above circumstances, the line sensor 10 is conventionally used.
Since the direction of the lamp filament F with respect to the scanning direction of the reading system by No. 7 is performed without consideration, there is a problem that inconvenient unevenness of the light amount is generated on the image.

Therefore, the present invention was made in order to solve the above-mentioned problems of the conventional example, and its purpose is to eliminate the unevenness of the light amount caused by the difference in the light distribution characteristics depending on the coil direction of the lamp filament. To provide a reading device.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a transparent original is illuminated by a lamp having a coiled filament, and an image of the entire transparent original is projected on an original table. And a reading unit arranged in the main scanning direction for reading the projection image projected on the platen by the projection unit. The reading image is further scanned in the sub scanning direction by the reading unit. In the projection image reading device that reads the entire projected image, the coil direction of the filament of the lamp is the same as the main scanning direction of the reading unit, and when reading the projection image, the output in the main scanning direction from the reading unit is corrected. The shading correction is performed.

(Operation) In the present invention having the above configuration, the coil direction of the filament of the lamp of the projection means is the same as the main scanning direction of the reading means, and when the projection image is read, the output in the main scanning direction from the reading means is By performing the shading correction, the light distribution is made uniform.

(Example) Below, this invention is demonstrated based on the Example shown in figure. Second
FIG. 1 is a schematic configuration diagram showing an embodiment of a projection image reading device according to the present invention. In FIG. 1, reference numeral 1 denotes a main body of a copying apparatus as a main body of the projection image reading device. A projection device 10 is provided, and the reflection mirror 2 and the Fresnel lens 3 are placed on a document table glass 4. A lamp (projection light source) 11, a lens 12, a slide film 13 which is a transparent original, and a projection lens 14 are mounted in the projection device 10. In the main body 1, an image forming lens 6 which is a gradient index optical transmission body and a line sensor 7 as a reading means are arranged. Further, the Fresnel lens 3 is for imparting directivity to a light beam having a spread in the projection direction as shown in FIG. 3, and FIG. 3 shows the state of the light beam in the system excluding the reflection mirror.

A case where the projection image of the slide film 13 is copied in the above configuration will be described. Lamp (projection light source) 1
The light emitted from No. 1 passes through the lens 12 and illuminates the slide film 13, and the illuminated light from the slide film 13 is projected onto the platen glass 4 via the projection lens 14, the reflection mirror 2 and the Fresnel lens 3. It The projection image projected on the platen glass 4 is imaged on the line sensor 7 by the imaging lens 6 as in the case of a normal reflection original.
The image information read by the line sensor 7 is transferred to and printed by a printer unit such as a laser beam printer.

By the way, the projection image of the slide film 13 projected by the projection device 10 is formed on the upper surface of the document table glass 4. The light quantity distribution on the platen glass 4 depends on the light distribution characteristic of the lamp 11. In FIG. 1, A is a line sensor 7
Of the filament sensor F, and B is the sub-scanning direction of the line sensor 7 (scanning direction).
By arranging the coil direction (winding axis direction) of FIG. 6 to be the main scanning direction, the light distribution characteristic of FIG. 4 is obtained in the A direction, and the light distribution characteristic of FIG. The light distribution characteristics shown in are to be applied. 4 and 5 show the light distribution characteristics of a halogen lamp (JC-24V150W), FIG. 4 shows the light distribution characteristics in the lamp width direction, and FIG. 5 shows the light distribution characteristic in the lamp length direction. It shows the characteristics.

Further, in general, when a reflective original or a transparent original is read by the line sensor 7, shading correction for correcting unevenness in sensitivity of the sensor or uneven light amount in the main scanning direction (reflected light or transparent original on a standard white plate during prescan) is performed. In order to correct the actual output data with reference to the projected light in the state where the lamp is removed, the lamp is oriented so that the coil of the filament F of the lamp 11 is in the A direction (main scanning direction). By arranging 11, the line sensor 7 can read the light amount unevenness due to the density of the coil of the filament F, which is inconvenient for the image as shown in FIG. 4, and the output including the error due to this light amount unevenness. Can be corrected by performing the above shading correction. Therefore, there is a lamp 11 having a coiled filament F. Image of the entire transparent original can remove the influence of uneven light distribution it is possible to read correctly.

Since the shading correction including the main scanning direction and the sub scanning direction is not generally performed because a large amount of image memory is used, it is obvious that this embodiment is an effective means.

(Effect of the Invention) The projection image reading device according to the present invention has the above-described configuration and operation. Since the coil direction of the filament of the lamp is the same as the main scanning direction of the reading means, the light amount due to the density of the coil of the filament is different. The unevenness can be read by the reading means, and the output including the error due to the uneven light amount is corrected by the shading correction, so that the influence of the uneven light distribution of the lamp having the coiled filament is eliminated. Thus, the image of the entire transparent original can be read correctly.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a projection image reading apparatus according to the present invention, FIG. 2 is a schematic configuration diagram of the same embodiment, and FIG. 3 is an explanatory view showing an operation of a Fresnel lens in the same embodiment. ,
4 and 5 are graphs showing the light distribution characteristics of the lamp, FIG. 6 is a front view showing the details of the lamp, and FIG. 7 is a schematic configuration diagram showing an example of a conventional projection image reading apparatus. Explanation of reference numerals 1 ... Copying apparatus main body (projection image reading apparatus main body), 2 ... Reflecting mirror, 3 ... Fresnel lens, 4 ... Original platen glass, 6 ... Imaging lens, 7 ... Line sensor (reading means) 10 ...... Projector, 11 ...... Lamp 13 ...... Slide film (transparent document)

Claims (1)

[Scope of utility model registration request] 1. A projection means for illuminating a transparent original by a lamp having a coil-shaped filament and projecting an image of the entire transparent original on an original table, and a projection image projected on the original table by the projection means. And a reading unit arranged in the main scanning direction, wherein the reading unit further scans the projection image in the sub-scanning direction to read the entire projection image. A projection image reading apparatus, which is the same as the main scanning direction of the reading means, and which performs shading correction for correcting an output in the main scanning direction from the reading means when reading a projected image.