JPS62279322A - Copying machine - Google Patents

Abstract

PURPOSE:To obtain proper images without being affected by the transmissivity of a subject by providing a sensor for size detection and a sensor for density detection with proper spectral sensitivity characteristics according to their uses. CONSTITUTION:When images 6A and 6B are formed on an original in the density order, the size detection sensor 8 senses an edge 6D of the original 6 as the leading edge of a signal in either case because its sensitivity is almost zero in a wavelength area of a pressure plate where the reflective index is high. The length, i.e. size of the original 6 is found from the original detection time ts so far and a scanning speed. A nearly equal output voltage is obtained as the detection output of the density detection sensor 18 regardless of whether the original is thick or thin because the spectral sensitivity characteristic of the sensor 18 extends to the peak wavelength of the reflective index of the pressure, and density suitable to a photosensitive body is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying machine, and more particularly to a copying machine equipped with means for detecting the size and density of a document.

[Prior Art] Conventionally, this type of copying machine has been configured to detect both the size and density of the original to be copied using a single optical detection sensor. When the above detection is performed on two different types of originals, even if the manually applied light amount or the spectral sensitivity of the photoreceptor is equivalent, the above is true for originals with high transmittance such as tracing vapor. The relative light amount in the sensor sensitivity area is affected by the spectral reflectance from the document pressure plate and decreases by 1.
If automatic density adjustment (AE) is performed based on the density data, a proper image cannot be obtained.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional art, to provide a copying machine that can obtain images of appropriate density regardless of the transmittance, and that improves the sharpness of color. The aim is to provide the opportunity.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a pressure plate that presses and holds an object placed on a transparent base, and a pressure plate that projects light from below the transparent base. and a light detection means for detecting reflected light from the object to be copied, and a copying machine capable of detecting the size and density of the object to be copied by the output signal from the light detection means, which has the spectral sensitivity of the photoreceptor. Among the wavelength ranges, the light detection means for size detection has high sensitivity in the short wavelength range, the light detection means for concentration detection has almost the same spectral sensitivity as the photoreceptor, and the light detection means has low reflectance in the short wavelength range. It is characterized by comprising a pressure plate.

[Function] In the copying machine of the present invention, the size detection sensor and density detection sensor are provided with appropriate spectral sensitivity characteristics according to their respective uses, so that the transmittance of the object to be copied can be adjusted. Appropriate images can be obtained in all cases without being affected by the color difference, and it has become possible to significantly improve the color sharpness compared to the conventional method.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

1A and 1B show an example of a copying machine of the present invention,
In these, 1 is a main body of the copying machine, 2 is a glass document table provided on its upper surface, 3 is a reference member for regulating the position of the document, and 4 is a panel for copying al operation. Furthermore, as shown in FIG. 1B, a document pressure plate 5 is provided on the upper surface side of the document table 2, and covers and suppresses the document 6 placed on the document table 2 with its reflective surface facing downward. be able to.

Reference numeral 7 is provided on the lower surface side of the document table 2, and includes a document size detection sensor 8, a density detection sensor 18, and a first reflection mirror 9.
The lamp support 10 also includes a lamp support that can scan along the recording surface of the original 6, and 10 is a lamp mounted on the lamp support 7 for illuminating the original.

Therefore, the light emitted from the lamp 10 is reflected from the recording surface of the original 6, and the normal copying operation is performed by an optical system (not shown) via the first mirror 9. However, before that, the original is scanned. At this stage, the document size detection sensor 8 determines the document density size, and the document density detection sensor 18 determines the original fA? Degree A is detected.

FIG. 2 shows an example of the configuration of the document detection section according to the present invention, where 11 is an amplifier circuit that amplifies the detection signal from the document size detection sensor 8, and 21 is an amplification circuit that amplifies the detection signal from the document density detection sensor 18. 12 is a copying process control circuit.

Next, the recording density and size detection operation in the copying machine configured as described above will be explained. Prior to that, the optical characteristics of the members involved in copying and each sensor are shown in FIGS. 3A to 3A.
This will be explained with reference to FIG. 3F.

First, the document size detection sensor 8 and the density detection sensor 1
8, as shown in Fig. 3A, the voltage V as the output signal changes temporarily with respect to the amount of incident light.
Furthermore, this sensor 8 has high spectral sensitivity in a relatively short wavelength region, as shown in FIG. 3B.

The original 6, which is the object to be copied, has spectral reflection characteristics as shown in FIG. 3D, while the reflected light from the original pressure plate 5 has spectral reflection characteristics as shown in FIG. The reflectance peak is located in a longer wavelength region than in Figure 3B. Therefore, when the reflected light from the original 6 and the original pressing plate 5 is detected by the sensor 8 having the above-mentioned spectral sensitivity characteristics, the sensitivity of the sensor 8 is approximately; By being close to
The output of the sensor 8 due to the reflected light from the document pressure plate 5 is 0.05, and the presence of the document can be detected from the generation of the output of the sensor 8.

On the other hand, the spectral sensitivity of the density detection sensor 18 has a region that almost coincides with the spectral sensitivity region of the photoreceptor (see FIG. 3F), as shown in FIG. 3C. 6 concentration can be detected.

Now, assuming that images 6A and 6B are formed on N document 6 in the order of shading as shown in FIG.
A copying operation is started by operating a copy key (not shown) on the operation panel 4, but first, before copying, the lamp 1 is
0 is lit, and scanning for detecting the size and density of the original 6 is performed.

In this way, the size detection signal from the size detection sensor 8 is appropriately amplified by the amplifier circuit 11, and the density detection signal from the density detection sensor 18 is appropriately amplified by the amplifier circuit 21, but if the original 6 is thick, that is, the transmittance is low. When the amplified size detection output and concentration detection output are as shown in FIGS. 5A and 5B, respectively, and when the original g46 is thin, that is, the transmittance is high, the size detection output and the concentration detection output are as shown in FIG. The detection outputs are as shown in FIG. 5C and FIG. 5D, respectively.

That is, as is clear from FIGS. 5A and 5C, the size detection sensor 8 has a nearly flat sensitivity in the wavelength region where the pressure plate has a high reflectance. The edge 6D is taken as a falling edge of the signal, and the length, that is, the size, of the original 6 can be detected from the original detection time tS and the scanning speed up to that point.

Note that here, vth is a threshold value, and T is a scanning time.

Furthermore, the detection output from the concentration detection sensor 18 is
As shown in Figures C and 5F, the spectral sensitivity characteristics of the sensor 18 extend to the peak wavelength of the reflectance of the pressure plate, so almost the same output voltage can be obtained regardless of whether it is thick or thin. It can be seen that each concentration appropriate for the photoreceptor was detected.

In the above explanation, it is assumed that the document size detection sensor 8 and the density detection sensor 18 are attached to the lamp support base 7 to scan one line, but these detection sensors are replaced by a line sensor parallel to the lamp 10. Alternatively, if it is formed by an area sensor and has an optical configuration like a well-known image scanner, it is possible to more accurately read the document position and density.

Furthermore, it goes without saying that the concentration detection sensor 18 may be replaced by a sensor that reads the surface potential of the photoreceptor.

[Effects of the Invention] As explained above, according to the present invention, there is provided a size detection means having high sensitivity in the shorter wavelength region among the wavelength regions having the spectral reflectance of the object to be copied; Since a pressure plate for the object to be copied has a low reflectance and a density detection means having a spectral sensitivity almost equivalent to that of the photoreceptor are provided, the appropriate density can always be obtained regardless of the transmittance of the object to be copied. Detection has become possible, high-quality copy images can always be obtained, and color tone properties can be significantly improved.

[Brief Description of the Drawings] Figures 1A and 1B are a top view and a sectional view, respectively, showing an outline of a copying machine to which the present invention can be applied. A block diagram showing an example, FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D, FIG. 3E, and FIG. Spectral sensitivity characteristics of the sensor, spectral sensitivity characteristics of the same density detection sensor, spectral reflectance characteristics of the object to be copied, and distribution characteristics of pressure plate reflectance l
Characteristic curve diagram showing the spectral sensitivity characteristics of the photoreceptor, No. 4
The figure is a schematic diagram showing an example of an m-light image on a manuscript. 5. Figure A,
Figures 5B, 5C, and 5D are waveforms showing the size detection output and density detection output when the document shown in Figure 4 is thick, and the size detection output and density detection output when the document is thin, respectively. It is a diagram. DESCRIPTION OF SYMBOLS 1... Copy machine, 2... Original table, 4... Operation panel, 5... Original pressure plate, 6... Original, 6A, 6B... Image, 6D... Edge, 8 . . . Original size detection sensor, 10. Lamp, 11.21. Amplification circuit, 12. Control circuit, 18. Original density detection sensor. Figure 1A Figure 1s @ Ward'tQ-Q @ 'Xze Battle Figure 5A Figure 5C Figure 5B Figure 5D

Claims (1)

[Claims] A pressure plate that presses and holds an object to be copied placed on a transparent table;
a light detection means for detecting light reflected from the pressure plate and the object to be copied by light projected from below the transparent table;
In a copying machine capable of detecting the size and density of the object by the output signal from the photodetector, a size detection device having high sensitivity in a short wavelength region among the wavelength regions in which the photoreceptor has spectral sensitivity is provided. A copying machine comprising: a light detection means, a light detection means for density detection having a spectral sensitivity substantially equal to that of the photoreceptor, and the pressure plate having a low reflectance in the short wavelength region.