JPH0467030A - Original reader - Google Patents

Abstract

PURPOSE:To make the ratio of an image signal to a white reference signal constant by providing a light guide member which guides light on the center side of a fluorescent lamp and irradiates a white reference plate with the light. CONSTITUTION:This reader is provided with the light guide member 105 which guides the light on the center side of the fluorescent lamp 104 and irradiates the white reference plate 103 with the light. In such a case, the light guide 105 is such constituted that a part of (or all of) the surface in contact with the fluorescent lamp 104 and a surface on the white reference plate 103 side transmit the light and the surface other than the above surfaces does not transmit the light, so that the light made incident from the surface in contact with the lamp 104 passes through the inner part of the light guide 105 and is allowed to irradiate the white reference plate 103 from the surface on the plate 103 side. Thus, the ratio of the image signal in an original reading area and the white reference signal of the white reference plate is always made constant without receiving the effect of the change of illuminance distribution occurring by the elapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an original reading device that normalizes an image signal in an original reading area using a white reference signal from a white reference plate. The present invention relates to a document reading device that can perform normalization.

[Conventional technology]

Irradiating the light of a fluorescent lamp onto a predetermined white reference plate and a document reading area, and using the reflected light from the white reference plate as a white reference signal,
As an example of a document reading device that normalizes an image signal in a document reading area, there is a color document reading device disclosed in Japanese Unexamined Patent Publication No. 61-30865. This color document reading device is
As shown in Figure 3, the contact glass (original [mounting stand])
301, a white reference plate 302 is arranged at the end in the main scanning direction in parallel with the document reading area 301a. By arranging the white reference plate 302 in this manner so that a white reference signal can always be input, the white reference plate 302 can automatically balance the white even if the original to be read has few white parts, such as a color photograph. Moreover, since the white balance can always be normally obtained, an image signal with good color reproducibility can be obtained even if a change in the light amount of the light source occurs.

However, with the method of arranging the white reference plate 302 at the end in the main scanning direction shown in FIG. 3, it is possible to always input the white reference signal, but the white reference plate 302 may become dirty or
Alternatively, when the whiteness partially decreases due to changes over time, the value of the white reference signal changes depending on the position of the white reference plate 302, and a stable white reference signal cannot necessarily be obtained. Therefore, as a solution to this problem, a document reading device has been proposed in which a white reference plate 407 is arranged on a carriage part 406 and the white reference plate 407 is moved together with the carriage part 406, as shown in FIG. has been done. This document reading device places a document 401 on a contact glass 402, illuminates the document 401 and a white reference plate 407 with a fluorescent lamp 403, and
1 and a white reference plate 407 are imaged on a color sensor (CCD 1x color sensor) 405 via a SELFOC lens array 404 which is a 1x imaging element. SELFOC lens array 404.
Color sensor 405. as well as.

A carriage section 406 is configured by the white reference signal 07. Therefore, when the carriage unit 406 moves in the six arrow directions in the figure to scan the original 401, the white reference plate 407 also moves at the same time. It will be input as a reference signal. In other words, by making the reflecting surfaces of the white reference plate 407 the same, the reflection conditions of the reflected light are made the same regardless of the scanning position in the sub-scanning direction.
The influence of dirt on the surface of the white reference plate 407 can be reduced.

[Problems to be Solved by the Invention] However, although the conventional document reading device in which a white reference plate is disposed in the carriage part can reduce the effects of dirt on the surface of the white reference plate, fluorescent lamps are used as the light source. Because changes in the illuminance distribution over time when using There is a problem in that the signal level is not constant and the signal level of the same density changes. In other words, the amount of light from a fluorescent lamp changes depending on the environment (especially temperature), so if you compare the situation immediately after lighting when the environmental temperature is low with the case when the environmental temperature has risen after a sufficient period of time, as shown in Figure 5. Therefore, differences appear in the overall amount of light and its illuminance distribution. Comparing this change in light amount between the document reading area in the main scanning direction and the position of the white reference plate, as shown in the figure, the amount of increase in light amount over time is different, so the image signal of the document reading area and the white of the white reference plate differ. The ratio of the reference signals is no longer constant, and the signal level of the same density changes.

The present invention has been made in view of the above, and the present invention always maintains a constant ratio between the image signal of the document reading area and the white reference signal of the white reference plate without being affected by changes in illuminance distribution over time. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention illuminates a predetermined white reference plate and an original reading area with light from a fluorescent lamp, uses the reflected light from the white reference plate as a white reference signal, and generates an image signal in the original reading area. The present invention provides a document reading device for normalization, which is provided with a light guide member that guides light from the center side of a fluorescent lamp toward a white reference plate and irradiates the white reference plate.

[Effect]

In the document reading device of the present invention, the light from the center of the fluorescent lamp is guided toward the white reference plate by the light guide member, and is irradiated onto the white reference plate.

〔Example〕

An embodiment of the document reading device of the present invention will be described below as shown in FIG. 1(a).
, (b) and FIG. 2, this will be explained in detail.

FIG. 1(a) shows the configuration of the scanning system of the document reading device of this embodiment, which includes a contact glass 102 of a transparent document surface substrate such as glass on which a document 101 is placed, and a contact glass 102 for obtaining a white reference signal. a white reference plate 103; a fluorescent lamp 104 for irradiating light onto the original 101 and the white reference plate 103;
The light from the center side of the fluorescent lamp 104 is guided to the white reference plate 103.
a selfoc lens array 106 that is a 1-magnification imaging element that guides reflected light from the original 101 and the white reference plate 103;
A color sensor (CCD equal-magnification color sensor) 107 photoelectrically converts reflected light incident thereon and inputs it. Note that 106a indicates a SELFOC holder, which includes a white reference plate 103, a fluorescent lamp 104. Light guide 105. SELFOC lens array 106. selfoc holder 10
6a and the color sensor 107 constitute a carriage section 108.

Therefore, in order to scan the original 101, the carriage unit 10
8 moves in the direction of arrow A in the figure, the white reference plate 103
Since both of the white reference plates 103 and 103 move at the same time, the reflected light from the same surface of the white reference plate 103 is input to the color sensor 107 as a white reference signal.

As mentioned above, the light guide 105 guides the light from the center side of the fluorescent lamp 104 and irradiates it onto the white reference plate 103, and it guides the light from the center side of the fluorescent lamp 104 and irradiates it onto the white reference plate 103, and it guides the light from the center side of the fluorescent lamp 104 and irradiates it onto the white reference plate 103. The surface on the 103 side is light-transmissive, and the other surfaces do not transmit light. Therefore, the light incident from the surface in contact with the fluorescent lamp 104 passes through the inside of the light guide 105 and is irradiated onto the white reference plate 103 from the surface of the white reference plate 103 example. FIG. 1 (■) is an explanatory diagram for explaining the shape and arrangement of the light guide 105.
It is arranged so as not to obstruct the path of the light irradiated to the fluorescent lamp 104, and the light from the side surface on the center side of the fluorescent lamp 104 is incident and guided to the white reference plate 103.

Further, in this embodiment, the light guide 105 is arranged such that the amount of light guided by the light guide 105 and irradiated onto the white reference plate 103 is approximately equal to the amount of light irradiated onto the original 101.
The shape (length, etc.) of is set.

FIG. 2 shows the illuminance distribution in the document reading device of this embodiment. By guiding light from the center side of the fluorescent lamp 104 using the light guide 105, as shown in the figure, the amount of change in the light amount at the position of the white reference plate 103 can be determined immediately after lighting and after light minutes have elapsed after lighting. The rate can be set to be the same as the amount of change in the amount of light in the document reading area. Therefore, the ratio of the image signal of the document reading area to the white reference signal of the white reference plate can always be kept constant, making it possible to read the image signal stably.

[Effects of the Invention] As explained above, the document reading device of the present invention irradiates light from a fluorescent lamp onto a predetermined white reference plate and a document reading area, and uses reflected light from the white reference plate as a white reference signal. , in a document reading device that normalizes an image signal in a document reading area,
A light guide member is provided that guides the light from the center of the fluorescent lamp toward the white reference plate and illuminates the white reference plate, so the document reading area is always illuminated without being affected by changes in illuminance distribution over time. The ratio between the image signal and the white reference signal of the white reference plate can be kept constant.

[Brief explanation of the drawing]

FIGS. 1(a) and 4) are explanatory diagrams showing a document reading device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing illuminance distribution in the document reading device of the present invention, and FIGS. 3 and 4. 5 is an explanatory diagram showing a conventional document reading device, and FIG. 5 is an explanatory diagram showing the illuminance distribution in the conventional document reading device. Explanation of symbols 101---One original 102---Contact glass 06a White reference plate 104- Fluorescent lamp light guide SELFOC lens array SELFOC holder color sensor carriage part

Claims (1)

[Scope of Claims] Light from a fluorescent lamp is irradiated onto a predetermined white reference plate and a document reading area, and the reflected light from the white reference plate is used as a white reference signal,
A document reading device that normalizes an image signal in a document reading area, further comprising a light guide member that guides light from the center side of the fluorescent lamp toward the white reference plate and irradiates the white reference plate. A document reading device that uses