JPH01320856A - Color image scanner - Google Patents

Abstract

PURPOSE:To prevent color slurring of an outline to improve the resolution by irradiating the surface of an original with the light emitted from a luminance signal light emitting element and the light emitted from a color signal light emitting element so that they are focused on this surface and detecting the reflected light by a luminance detecting element and a color signal detecting element. CONSTITUTION:The light from a laser diode 21 for luminance signal and red, green, and blue light from LEDs 22, 23, and 24 are made incident on a scanning mirror 18, and these light are synthesized by dichroic prisms 25, 26, and 27 and are made incident there through a focus lens 20. These light are synthesized and are focused on an original 11 wound around the outside surface of a cylinder 10. The reflected light from the surface of the original 11 is received by an arcuate incidence part 12 of a light transmitter 12, and the incident light reaches an exit part 14. This light has the wavelength divided by three dichroic prisms 32, 33, and 34 and reaches a photodetector 28 for luminance, a photodetector 29 for red, a photodetector 30 for green, and a photodetector 31 for blue.

Description

[Detailed Description of the Invention] Field of Industrial Application) The present invention relates to a color image scanner, and in particular, to a color image scanner, in which a document is wrapped around the outer circumferential surface of a transparent cylinder, and light is irradiated onto the surface of the document from inside the cylinder. The present invention also relates to a scanner that is suitable for use in a scanner in which light reflected from a document is guided by a light guide to a first to a detector side.

KSummary of the invention] The present invention rotates a scanning mirror in the center of a transparent drum, irradiates light onto a document wrapped around the outer circumferential surface of the transparent drum, and directs the reflected light through a light guide. In the Iζ image scanner, a luminance signal light emitting element and a color signal light emitting element are arranged on the incident side of the scanning mirror, and the light extracted from the output part of the light guide is detected by the photodetector. In addition to combining the light from these elements and guiding it to the scanning mirror, a luminance signal detection element and a color signal detection element are arranged on the output side of the light guide, and these detect the luminance signal component and color of the light reflected from the original. The signal components are read out.

K. Prior Art Conventionally, contact type and reduction projection type image scanners have been known. In these image scanners, a line sensor is used as a light receiving section. When colorizing such an image scanner, a color filter 2 is attached onto the line sensor 1, as shown in FIG. The color filter 2 is made up of strips of red (R), green (G), and blue (B) color filters arranged in the same order. I try to paste it overlappingly.

Problem to be solved by the K invention: y According to color image scanning using a line sensor as shown in Fig. 4, the position of the light-receiving element is shifted for each color, resulting in color shift of the outline. Occur. Furthermore, since the light of each color is detected every third light receiving section of the line sensor 1, there is a drawback that the resolution is reduced to 1/3 and the size of the line sensor 1 is increased.

On the other hand, the applicant of the present application has previously proposed a cylindrical image scanner. This image scanner uses a scanning mirror tilted to the axis to irradiate a laser beam onto the surface of a document wrapped around the outer surface of a transparent drum, and also to emit reflected light from the surface of the document. The light is received by a light guide and detected by a photodetector.

However, this image scanner was not colorized and was configured as a black and white image scanner.

The present invention has been made in view of these problems, and an object of the present invention is to provide a color image scanner having an optical system that does not cause color shift, has high resolution, and has a compact sensor. It is something to do.

Means for Solving K Problem 1 The present invention comprises: a luminance signal detection element; a color signal detection element; a luminance signal light emitting element corresponding to the luminance signal detection element; and a color signal detection element corresponding to the color signal detection element. a light emitting element, the light emitted from the luminance signal emitting element and the light emitted from the color signal emitting element are focused on the document surface, and the light emitted from the luminance signal emitting element is focused on the document surface. The light reflected on the document surface is detected by the luminance signal detection element, and the light reflected from the document surface from the color signal light emitting element is detected by the color signal detection element.

K action] The light emitted from the luminance signal light emitting element and the light emitted from the color signal light emitting element =4- are combined and irradiated onto the document surface. The luminance signal component of the light reflected on the document surface is detected by the luminance signal detection element, and the color signal component is detected by the color signal detection element.

Embodiment K] FIGS. 1 and 2 show a color image scanner according to an embodiment of the present invention, and this color image scanner is equipped with a transparent cylinder 10 made of glass or transparent resin. ing. The original 11 is wound around the outer surface of the cylinder 10 over an angle of about 240 degrees, for example. Further, a light guide 12 is arranged inside the cylinder 10. The light guide 12 has a substantially trumpet-like shape with a missing lower end, and the outer circumferential portion thereof constitutes an arc-shaped entrance portion 13 . The entrance side portion 13 has an arcuate shape, thereby receiving reflected light from the original document 11 and functioning as a lens. On the other hand, the center side of the light guide 12 is configured as an output section 14, so that the light that has traveled through the light guide 12 in a completely reversed manner is output. Also, the side end surface of the light guide 12 is the reflective surface 1.
5 to prevent light from escaping to the outside from the side end surfaces. A motor 16 is disposed within the light guide 12, and a scanning mirror 18 is attached to its output shaft 17. Note that the output shaft 17 of the motor 16
coincides with the axis of the cylinder 10, and the scanning mirror 18 is attached to the output shaft 17 at an inclination angle of 45°.A focus lens 20 is disposed in front of the scanning mirror 18. This lens ゛2
Laser diode 21 and LED for injecting light into
22, 23, and 24 are arranged. The laser diode 21 is for generating a luminance signal, and also for LE
D22.23.24 are adapted to generate red, green, and blue light, respectively. Three dichroic prisms 25 are used to guide the light from these laser diodes 21 and LEDs 22, 23, and 24 to the lens 20.
．． 26.27 are arranged.

On the other hand, on the front side of the output surface 15 of the light guide 12, four first detectors 28, 29, 30, and 31 are arranged. The photodetector 28 is for detecting a luminance signal. The two photodetectors are designed to detect red color signals, and the photodetector 30 is designed to detect red color signals.
is designed to detect green color signals. Yet another one
The two photodetectors 31 are designed to detect blue color signals. Three dichroic prisms 32, 33, and 34 are arranged as shown in the figure so that the light emitted from the light guide 12 is supplied to the four photodetectors 28 to 31, respectively.

In the above configuration, the scanning mirror 18 is rotationally driven by the motor 16. Therefore mirror 18
The reflected light 3 scans the inside of the transparent cylinder 10 in the circumferential direction, and this becomes main scanning.

In contrast, the transparent cylinder 10 around which the original 11 is wrapped moves in the axial direction relative to the optical system inside the cylinder. This operation becomes sub-scanning. By scanning in these two directions, the inner surface of the document 11 is irradiated with light and scanned.

The light incident on the scanning mirror 18 includes light from the laser diode 21 for brightness signals as well as from the LED 22.
The red, green, and blue light from 23.24. These lights are combined by dichroic prisms 25, 26, 27, and passed through a focus lens 20 to a mirror 18.
is incident on the

Therefore, the original 11 in which the luminance signal light and the color signal light are combined and wrapped around the outer surface of the cylinder 10.
You will be tying the spots on top. This spot is as shown in Figure 3, and the laser beam 35 has a small light emitting point.
The light 36 from the LEDs 22, 23, and 24, which have large light emitting points, connects large spots. This difference in spot size lowers the resolution characteristics of the color signal, but this is not a particular problem because the human eye's ability to resolve color signals is considerably lower than that of luminance signals. do not have.

The reflected light from the surface of the original 11 is received by the arc-shaped entrance portion 13 of the light guide 12 . Use part 1 of this light guide 12
3 has an angle corresponding to the angle in the circumferential direction of the document 11, and therefore receives reflected light through the incident portion 13. The incident light then travels inside the light guide 12 while being totally reflected, and reaches the output section 14. Then, the light is emitted from the light guide 12 at the emission part 14, and this light is
The light is wavelength-divided by the dichroic prisms 32, 33, and 34, and reaches the luminance photodetector 28, the red photodetector 29, the green photodetector 30, and the blue photodetector 31, respectively.

That is, the luminance signal component of the light reflected from the original 11 is detected by the photodetector 28, and the color signal component is detected by the three photodetectors 29-31.

As shown in Figure 3, such a color image scanner has a high luminance resolution by using a small spot of laser light 35, and on the other hand, it has a high color resolution for color signals for which the resolution of the human eye is low. I try to get a color image that is as good as I need it without being overly saturated. In the signal obtained by such an image scanner, the luminance signal component extends to a high spatial frequency. On the other hand, the light from the LEDs 22 to 24 is averaged over a wide range and does not extend to high frequency regions.

By using such an optical system, it becomes possible to colorize a cylindrical scanning type image scanner with a simple and compact structure. Furthermore, there is no unevenness in sensitivity due to variations in elements, and high resolution can be achieved at low cost. In addition, expensive optical elements, large projection lenses, line sensors with multiple SELFOC lenses, etc. are no longer necessary. Since each color can be roughly detected on the same axis, color shift does not occur. Further, there is no restriction in the length direction of the document 11, that is, in the axial direction of the cylinder 10.

K Application Example The present invention has been described above with reference to the illustrated embodiment, but the present invention is not limited to the above-described embodiment, and various modifications can be made based on the technical idea of the present invention. For example, by using a red laser diode as a laser diode for brightness signals, this laser diode also serves as an element for red color signals, which makes it possible to reduce the number of light sources. .

[Effects of the Invention] As described above, the present invention irradiates the light emitted from the luminance signal light emitting element and the light emitted from the color signal light emitting element so that they are both focused on the document surface, and uses the reflected light to adjust the luminance. Detection is performed using a signal detection element and a color signal detection element. Therefore, with such a configuration, it is possible to prevent color shift of the outline and also to provide a high-resolution color image scanner.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the optical system of a color image scanner according to an embodiment of the present invention, FIG. 2 is a perspective view showing the structure of the drum and light guide, and FIG. 3 is a plan view of the beam spot. , FIG. 4 is an exploded perspective view of a line sensor of a conventional color image scanner. The names of the main parts in the drawings are as follows. 10... Transparent cylinder 11... Original 12... Light guide 13... Arc-shaped entrance section 14... Output section 18... Scanning mirror 20...Focus lens 21...LD (laser diode) 22-24.
・LED

Claims (1)

[Claims] 1. A luminance signal detection element, a color signal detection element, a luminance signal light emitting element corresponding to the luminance signal detection element, and a color signal light emitting element corresponding to the color signal detection element. The light emitted from the luminance signal light emitting element and the light emitted from the color signal light emitting element are focused on the document surface, and the light emitted from the luminance signal light emitting element is reflected from the document surface. is detected by the luminance signal detection element, and reflected light from the document surface of the light emitted from the color signal light emitting element is detected by the color signal detection element.