JPS59144268A - Color reader - Google Patents

Abstract

PURPOSE:To perform calibration easily against adjustment deterioration due to a secular change by calibrating the gains of respective sensors in charge of constituent colors to specific values over a look at a monitor by using a means for switching to an adjustment mode and a calibration reference before a picture is read. CONSTITUTION:Mode changeover switches (SWs) 9, 9', and 9'' for read/adjustment mode switching, gain adjusting devices 10, 10', and 10'' for varying the gains of amplifiers 6, 6', and 6'', and indicators (IDs) 11, 11', and 11'' which display the output of a device are provided. The SWs 9, 9', and 9'' are turned on before the picture is read, and while the IDs 11, 11', and 11'' for the respective colors R, G, and B are monitored, the adjusting devices 10, 10', and 10'' are adjusted so that they indicate reference values VR, VG, and VB. Thus, the calibration is performed to correct the influence of secular changes in the quantity of light of an illumination light source 2 and characteristics of sensors 5, 5', and 5''.

Description

[Detailed Description of the Invention] (A so-called color reading device that reads the color tone or color α degree based on the component ratio or output amount of each component color read by the sensor assigned to each field. In particular, the present invention relates to a method for calibrating the readout signal in an apparatus that detects and amplifies the component concentrations of, for example, three component colors corresponding to one point on a readout object as a readout signal, and reads out the readout signal as a readout signal.

(Prior art) Conventionally, images such as characters, figures, and photographs have been detected in units of pixel groove formations: for example, charge-coupled devices, which are a group of photodetecting elements arranged one-dimensionally with one main scanning width or a unit main scanning width, are arranged. ,
(so-called CCD), the density of the image for each unit pixel is determined by the main scanning of the sensor, and the sub-scanning of the movement of the medium on which the image to be read is written, and the pixel group that constitutes the surface containing the object to be read. Reading devices that read output signals configured as It has a sensor for the constituent colors and a filter that separates the constituent colors into color components, and reads out an image as density signals of the constituent colors, and has a configuration as shown in FIG. 1, for example.

FIG. 1 is an explanatory diagram of a conventional example, in which 1 is a medium on which an image to be read is placed, such as a document, 2 is an illumination light source,
3 and 3' are so-called dichroic mirrors which are filters that separate into color components using selective reflection, and 4.4' and 4'' are extinction type lenses *5 and 5'.

Reference numerals 8' and 8'' are AD converters, which are not particularly shown, but are drive control means of an apparatus that includes a conveyance means and control means for sub-scanning or back-scanning the document 1, and four scanning control means for the central and secondary scans. It is assumed that this is provided as a matter of course.

In this configuration, the original 1 is illuminated by the illumination light source 2, and this reflected light is separated into three lights: red, green, C), and (B) by the dichroic mirror 3.3'.

The light that has been separated into three parts is each passed through a lens 4.4'.
The light is focused by 4" to form an image on sensors 5, 5', and 5". And each sensor output is AnoPro, 6'
, 6", and then passed through sample water t-field circuits 7.7', 7", and multivalued to, for example, 256 levels by A/D converters 8.8', 8".
The white level (output for a white original) of each sensor output for R, GIB (obtains a statement) is determined by the illumination light source 2.
, dichroic mirrors 3, 3' setters 5° 5', 5", etc., so in order to make them the same, the gains of the amplifiers 6.6', 6" are set to RGB.
It is necessary to adjust each value separately. This white level must be adjusted more precisely as the number of division levels of A/D conversion increases. Accurate color reading (the color of the document and the output of the IT device cannot always correspond accurately) is possible. However,
In the configuration shown in Figure 1, the gain of the amplifier is normally adjusted when assembling the device, but it has the disadvantage that it is not possible to prevent deterioration of color reading performance due to subsequent changes in the light intensity and light emission characteristics of the illumination light source over time. Ta.

(Purpose and Features) In view of the above, an object of the present invention is to provide an apparatus capable of carrying out a calibration method that can easily realize adjustment whenever necessary in order to cope with adjustment deterioration due to changes over time. In order to achieve the above object, the present invention is characterized by separating the image on the object to be read into component colors to be read and forming the image on a sensor that separately detects the density of each component color. In addition to the reading mode in which the above-mentioned reading is carried out in a color reading device that reads the image as surface pixel information for each constituent color, there is also a means for switching to an adjustment mode for adjusting the output gain Vt of each sensor, and each of the reference densities. It has a calibration standard with component colors prepared and a means for monitoring the level of the output signal, and in test mode, the gain of each sensor system that shares each component color is measured by using the above calibration standard while observing the above monitoring means. This is to calibrate each to a predetermined value.

(Embodiment) FIG. 2 is an explanatory diagram of an embodiment of the present invention. The difference from FIG. 1 is that in addition to the basic configuration of FIG. 1, there is a mode changeover switch 9 for switching between the reading mode and the adjustment mode. 9', 9" and a gain adjuster 10.10' that can change the gain of the amplifiers 6.6', 6".

10" and an indicator 11゜1 that displays the entire output of the device.
1' and 11'' are provided.

When it is on, it is in adjustment mode. In the adjustment mode, the CCD output for each of R, G, and B is +
Read a standard document that is known to be 'Vc y VI3, and while looking at the indicators 11. pvB
Adjust so that According to this embodiment, before reading,
By calibrating the device output, it is possible to completely correct the effects of changes over time in the light intensity and light emitting characteristics of the illumination light source, and it is possible to accurately match the color of the original to the device output. effective.

Further, FIG. 3 shows another embodiment of the present invention. The configuration shown in FIG. 3 differs from that shown in FIG.
'ji7, amplifier changeover switch 12° RGB output changeover switch B was all connected. In this embodiment, a mode changeover switch gain adjuster 10. This has the effect of reducing the number of indicators 11 to one each, resulting in lower costs.

(Effect) is prepared as a calibration standard, and on the equipment side there is a switch to switch the equipment to test mode, an indicator to monitor all the gain output of each amplifier, and a gain adjustment control to adjust all the gains of each amplifier, and put the equipment into test mode when necessary. On the other hand, by adjusting the gain of each component output of the device based on the calibration standard, a characteristic effect is produced in that the device can always be maintained in a well-adjusted state.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional example, FIG. 2 is an explanatory diagram of one embodiment of the present invention, and FIG. 3 is an explanatory diagram of another embodiment of the present invention. 11, 11', xx'; indicator, 2 illumination sources, 7 + "t"' sample hold circuit, 12 A/G cut-off switch, 3.3' dichroic mirror, 8.8', 8" A/D Conversion circuit, 1
3RCB output selector switch, 4, 4/, 4//lens, 9.9', 9" mode selector switch, 5.5',
5" CCD. 10.10', 10" gain adjuster

Claims (1)

[Scope of Claims] i> The image on the object to be read is separated into component colors to be read, and the image is formed on a Nananosa which divides and detects the density of each component color. In addition to the reading mode in which the above-mentioned reading is carried out, a color reading device that reads the information as surface pixel information is provided with means for switching to an adjustment mode in which the output gain # of each of the above-mentioned sensors is adjusted, and each component color of the standard density. 1. A color reading device, wherein the color reading device is calibrated to a predetermined value while looking at the calibration standard and the overall level monitor of the output signal.