JPH0339978Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a document reading mechanism, and more particularly to a document reading mechanism in a diagnostic system using transmissive and reflective documents.

[Conventional technology]

A conventional document reading mechanism in a diagnostic system that reads and files a transparent document such as an X-ray film and a medical certificate which is a reflective document has a dedicated reading section for a transparent document and a reflective document. Therefore, the space required for the document reading mechanism is approximately twice as large, and the price is also approximately twice as large.

[Problem that the invention attempts to solve]

That is, the conventional document reading mechanism has the disadvantage of being large and expensive in a system that uses both a transmissive document and a reflective document.

[Means for solving problems]

The document reading mechanism of the present invention is placed on one side of the document in a system that shares transmissive and reflective documents, and irradiates the vicinity of the scanning area from a direction approximately perpendicular to the document surface of the transmissive document. A first light source, a second light source that is placed on the other side of the document and irradiates the vicinity of the scanning area of the document for reflection, and a second light source that is placed on the second light source side and extends along the direction perpendicular to the conveyance direction of the document. A one-dimensional image sensor in which a plurality of photo sensors are arranged linearly at approximately equal intervals, and transmitted light from a first light source and reflected light from a second light source are formed into an image on a light receiving surface of the one-dimensional image sensor. and a plurality of ND filters, one of which is selectively inserted into the optical path of transmitted light and reflected light, each having a different transmittance.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a side view of essential parts of an embodiment of the present invention, in which the document reading mechanism has a transmission light source 11 as a first light source.
, a reflective light source 12 as a second light source, a CCD 13 as a one-dimensional image sensor, and a lens 14.
and a filter group 15.

In FIG. 1, light from a transmission light source 11, which is a rod-shaped light source such as a fluorescent lamp, uniformly illuminates the vicinity of a scanning region 17 on the upper surface of a document 16 from a direction substantially perpendicular to the surface of the document. Similarly, the light from the reflective light source 12, which is a rod-shaped light source, is transmitted to the scanning area 1 on the lower surface of the original 16.
7 uniformly irradiate the vicinity.

When the original 16 is a transmission original such as an X-ray film, the transmission light source 11 is selectively turned on and the reflection light source 12 is turned off. In addition, in the case of reflective originals,
The reflection light source 12 is turned on and the transmission light source 11 is turned off.

The transmitted light or reflected light from the original 16 in the scanning area 17 passes through any one of the ND filters F ₁ , -, F ₆ disposed in the filter group 15 inserted in the optical path, and is reflected by the lens 14 . The position of the lens 14 is set so that an image is formed on the light receiving surface of the CCD 13.
However, the CCD 13 is a one-dimensional image sensor in which a plurality of photo sensors are arranged in a straight line at approximately equal intervals along the direction perpendicular to the conveying direction A, and corresponds to the scanning area 17 of the original 16 by self-scanning. Perform main scanning on the scanning line.

ND filters F ₁ , ~, F ₆ are for setting the light intensity of the transmission light source, which will be described later.
As shown in FIG. 2, ND filters F ₁ , _.

In this example, the transmittance of each of the ND filters F ₁ , ~, and F ₆ is set in 10% steps in the range of 30% to 80%, taking into account the light intensity deviation value of a fluorescent lamp as an example. .

The original 16 is transported by a transport mechanism (not particularly shown).
The paper is conveyed on the guide plate in the conveyance direction A at a predetermined sub-scanning speed, and sub-scanning is performed.

Next, with reference to FIG. 3, the initial light amount setting and the light amount adjustment when replacing the fluorescent lamp after use will be described.

The initial light amount setting is performed for the transmission light source 11. The reasons for this are as follows. That is, X
Since a transparent original such as a line film is a photograph, an output level corresponding to the density of the film must be obtained from the CCD 13. Further, the white level obtained from the transparent original should not be higher than the value of the reference white level to which the white reference level is matched, and should be as close as possible. The transmitted light is compared to the reflected light.
Since the amount of light incident on the CCD 13 is large, it is necessary to prevent the CCD 13 from reaching its saturation point.

On the other hand, reflective originals usually have binary information in black and white.
The output signal from the CCD 13 can be converted into black and white binary data, and has a wide tolerance range for output level values for white and black.

FIG. 3 is an example obtained experimentally. CCD
The output saturation level of No. 13 is 500 mV, and the shaded area in Fig. 3 is the saturation area.

With the document 16 not present in the scanning area 17, the transmission light source 11 is turned on, and the ND filter is set to "F ₁ " (transmittance
30%) to correct the shading caused by the lens 14.

Next, one of the ND filters F ₁ to F ₆ is selected, and the output level from the CCD 13 is set to a value close to 500 mV and not exceeding 500 mV.

When using a transparent original, the reference white level is transmitted by setting the gain of the output signal amplifier of the CCD 13 to 0.6 times with the original 16 not in the scanning area 17.
Therefore, the reference white level is 300mV.

Since the film transmittance of developed X-ray film at the end of exposure is approximately 60%, when the X-ray film is set as a transmission original in the scanning area 17, the output level from the CCD 13 for white is smaller than 300 mV and close to it. value and satisfies the above conditions.

CCD for white level (density 0.03) of reflective original
The output level from the CCD 13 is approximately 30% of the output level from the CCD 13 for the transmission light source 11 when there is no document. Therefore, since the output level from the CCD 13 for the white of the reflective original is approximately 150 mV, binarization is performed based on this value.

To adjust the light intensity when replacing the transmission light source 11 after use, adjust the ND so that the output level from the CCD 13 is close to 500 mV without the document 16.
It is sufficient to select any one of the filters F ₁ , . . . , F ₆ . There is no particular need for adjustment for the reflection light source 12 when replacing it.

The transmission light source 11 and the reflection light source 12 each have an automatic light amount adjustment function that controls the amount of light emitted at a constant level over time and changes in ambient temperature. When the temperature drops, a warning to replace the fluorescent lamp will be issued. A description of the automatic light amount adjustment function will be omitted.

In this way, by providing _the ND filters F ₁ , .

[Effect of idea]

As explained above, the document reading mechanism of the present invention has a first light source that illuminates the scanning area from both sides of the document.
By providing a light source and a second light source, and adding multiple ND filters each having a different transmittance, one of which is selectively inserted into the optical path of transmitted light and reflected light, it is possible to Since the document reading section in a system for sharing documents can be realized in a small size and at low cost, and the light amount can be set extremely easily, the practical and economical effects on the system configuration are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a side view of essential parts showing an embodiment of the present invention;
FIG. 2 is a plan view of the filter group in FIG. 1, and FIG. 3 is an explanatory diagram showing an example of the relationship between the output levels of the CCD. In the figure, 11...transmission light source, 12...reflection light source, 13...CCD, 14...lens, 1
5... Filter group, F ₁ , ~, F ₆ ... ND filter.

Claims (1)

[Scope of utility model registration request] Transmissive and reflective originals are fed out in the conveying direction at a sub-scanning speed, and the vicinity of the scanning area is irradiated from a direction substantially perpendicular to the original surface of the transparent original, which is placed on one side of the original. a first light source; a second light source disposed on the side opposite to the one surface side and irradiating the vicinity of the scanning area of the reflective document; and a second light source disposed on the second light source side in the conveyance direction. a one-dimensional image sensor in which a plurality of photo sensors are arranged in a straight line at approximately equal intervals along a direction perpendicular to the image sensor; a lens that forms an image of the transmitted light and the reflected light from the second light source; and a lens that forms an image of the transmitted light and the reflected light from the second light source;
A document reading mechanism that includes a plurality of ND (neutral density) filters, each of which is selectively inserted and has a different transmittance.