JPH0642711B2 - Color printing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color printing apparatus.

(Background Art) In a conventional color printing apparatus such as a color ink jet printer, an object to be printed (hereinafter sometimes referred to as printer paper)
However, if a background color is used, the background color is emphasized, and the color of the original picture cannot be faithfully reproduced. This is because the conventional color printing apparatus does not have a means for controlling the input signal corresponding to the color of the printing object, and therefore, the printing paper or OHP paper with the ground color is printed. It was difficult to use it as a copy and perform high-quality printing.

<Purpose> In view of the above points, the present invention has an object to enable high-quality color printing, and in order to achieve such an object, the color printing apparatus of the present invention has a recording medium inserted in the apparatus. Detecting means for detecting
(This embodiment corresponds to FIG. 1 in FIG. 1) Color processing means for performing color processing on the input color image signal in order to record a color visible image corresponding to the input color image signal on the recording medium (also 29, 28), color recording means for recording a color visible image corresponding to the input color image signal color-processed by the color processing means (also in FIG. 1, FIG. 3) provided in the conveying path of the recording medium. Achromatic high-reflecting material (also in FIG. 1) A plurality of light-receiving elements (each having the same wavelength sensitivity characteristic as the light-emitting element provided on the opposite side of the conveying path from the achromatic high-reflecting material). 1 to 3 and 9 to 11), and capturing means for capturing the output of each of the plurality of light receiving elements in connection with the detection of the detecting means (also in FIG.
9), a control means (also FIG. 28 in FIG. 2) for controlling the color processing state of the color recording means on the basis of the output of each of the plurality of light receiving elements having a plurality of different wavelength sensitivity characteristics captured by the capturing means. Have.

(Description by Embodiments) Means taken in the present invention in order to achieve the above object will be described below with reference to the embodiments shown in the drawings. The following description will be made for the example in which the present invention is applied to an ink jet color printer, in the order of the configuration of the first embodiment of the present invention, its operation, and the second embodiment. The present invention can be applied to color printing apparatuses other than the ink jet printer.

(Structure of the first embodiment of the color printing apparatus of the present invention)
(FIGS. 1 and 2) FIG. 1 is a block diagram mainly showing a printer paper detecting means in a color ink jet printer which is an embodiment of a color printing apparatus of the present invention, and FIG. It is a block diagram. In these drawings, 1 is a printer sheet as an example of a printing object, 2 is a platen, 3 is a printer head, and the printer sheet 1 is fed into the apparatus in the direction of arrow A and wound around the platen 2. Printer head 3
The recording is performed by, and the paper is ejected to the outside of the device. In this example, the printer paper 1 is fed and recorded one by one. Reference numeral 4 is a white reflector, 5 is a mechanical paper detection sensor which is an example of a paper position detection sensor, and 6 and 7 are paper feed rollers. Reference numeral 8 is a light emitting portion of the paper color detection sensor, and the emitted light irradiates the printer paper 1 being fed. Similarly, reference numerals 9 to 11 are light receiving portions, which receive the light reflected by the printer paper 1 and output signals (hereinafter referred to as R ′, G ′ and B ′ signals) obtained by photoelectrically converting red, green and blue optical signals, respectively. To do.

In FIG. 2, reference numeral 21 denotes YMC for converting an input signal (R, G, B signals) to be printed into Y, M, C signals.
A conversion circuit, 22 is a gamma correction circuit, 23 is a lower color removal circuit, 24 is a masking circuit, and 25 is an OD-V conversion circuit for converting an optical density signal into a voltage. The configurations and functions of these circuits are well known. Therefore, detailed description will be omitted. Conventionally, the control system of a color printer is essentially composed of the above circuits, and the output of the gamma correction circuit 22 is directly input to the undercolor removal circuit 23. In contrast, the second
In the illustrated embodiment, the various circuits described below are provided to correct the input R, G, B signals by the output of the color detection means of the printer paper.

More specifically, 26 and 27 are interlocking switching switches, which are simultaneously controlled by the output of a delay circuit 32 described later. The R, G, B signals which are the input signals and the R ', G, B'signals which are the outputs of the above-mentioned light receiving sections 9 to 11 are switched and inputted to the switching switch 26 as will be described later. The output of the gamma correction circuit 22 is input to the switch 27. Reference numeral 28 denotes a subtraction circuit, which performs subtraction processing of the R, G, B signals from the switching switch 27 and the R ', G', B'signals stored in the latch circuit 29. Reference numeral 30 denotes a paper color detection sensor light emitting circuit, which drives and controls the light receiving unit 8. 31 to 33 are delay circuits,
The respective outputs control the latch circuit 29, the switching switches 26 and 27, the subtraction circuit 28, and the paper color detection sensor light emission circuit 30. Reference numeral 34 denotes a paper position detection sensor circuit, which operates according to the output of the paper position detection sensor 5.

(Operation of the first embodiment of the color printing apparatus of the present invention)
(FIGS. 1 and 2) When the printer paper 1 is sent from between the paper feed rollers 6 and 7 and the paper position detection sensor 5 detects that the printer paper 1 has been sent, the paper position detection sensor circuit 34 operates. Then, the output is applied to the paper color detection sensor light emitting circuit 30, and the light emitting section 8 emits light to illuminate the printer paper 1 being fed. At the same time, the output of the paper position detection sensor circuit 34 is supplied to the delay circuit 31, and the latch circuit 29 is turned on. The interlocking switching switches 26 and 27 are the switching switches 2 first.
The R ', G', and B'signals input to 6 are input to the YMC conversion circuit 21, and the gamma correction circuit 22 is connected to the latch circuit 29.
Connect to. On the other hand, since the light reflected by the printer paper 1 is received by the light receiving parts 9 to 11 of the paper color detection sensor, the output R ', G', B'signals are output by the YMC conversion circuit 21 and the gamma correction circuit 22. These signals which have been processed and stored in the latch circuit 29 are hereinafter referred to as Y ', M', and C'signals.

Then, after a delay time by the delay circuit 32, the switching switches 26 and 27 input the input R, G, B signals to the YMC conversion circuit 21, and the gamma correction circuit 22 causes the subtraction circuit 2 to operate.
8 to connect. During this time, the printer paper 1 is continuously fed, and at the same time, the delay circuit 33 takes timing to start printing, and the output thereof turns off the paper color detection sensor light emitting circuit 30 and turns off the light emitting unit 8 and the subtraction circuit 28. Turned on, Y, M, C obtained by YMC conversion of R, G, B signals
A difference signal between the signal and the Y ', M', C'signals (both gamma converted) is formed. The output of the subtraction circuit 28 is the undercolor removal circuit 23, the masking circuit 24, and OD-.
The signal is processed in a known manner in the V conversion circuit 25, and the output Y, M, C, and BK signals drive the printer head and start printing. Since the white color reflector 4 is used as the reflector in the paper color detection sensor section in FIG. 1, the OHP sheet is automatically regarded as white and can be printed on it. According to the above-described embodiment, the color is detected each time the printer paper 1 is fed, that is, for each printer paper, and the input R, G, B signals are corrected by the detection output, so that the ground color It is possible to faithfully reproduce the color of the original image without emphasizing the background color of the paper even when using the paper with a sheet or OHP paper. The present invention can be applied not only to an apparatus for feeding printer sheets one by one but also to an apparatus for continuous feeding.

(Second Embodiment of Color Printing Apparatus of the Present Invention) In carrying out the present invention, the paper position detection sensor (5 in FIG. 1) is used by utilizing the output of the paper color detection sensor as follows. It can be omitted and the device can be simplified. That is, the light emitting unit 8 of FIG. 1 is previously made to emit light, the printer paper 1 is fed while detecting the outputs of the light receiving units 9 to 11, and the timing when the output of the light receiving units 9 to 11 is changed is detected. Accordingly, a means for determining that the printer paper 1 has been fed to a predetermined position in the apparatus is provided, and the paper position detection sensor 5 of FIG. The subsequent processing may be performed.

<Effect> According to the present invention, the fact that the recording medium is inserted into the apparatus is detected, and the outputs of the plurality of light receiving elements having different wavelength sensitivity characteristics are taken in based on the detection, so that the recording medium The characteristics can be reliably discriminated. In particular, according to the present invention, an achromatic high-reflecting material is provided in the conveying path of the recording medium, a light emitting element provided on the opposite side of the achromatic high-reflecting material, and a plurality of light receiving elements each having different wavelength sensitivity characteristics. Since the elements are provided, the color characteristics of even a translucent recording material such as OHP can be well discriminated, and the color processing is controlled according to the color characteristics of the recording material. Good recording with excellent color reproducibility can be performed with any recording material.

[Brief description of drawings]

FIG. 1 shows an embodiment of a color printing apparatus of the present invention. FIG. 1 is a block diagram of a main part thereof, and FIG. 2 is a block diagram of its control system. DESCRIPTION OF SYMBOLS 1 ... Printer paper which is an example of an object to be printed, 4 ... White reflector, 5 ... Paper position detecting sensor, 8 ... Light emitting portion of paper color detecting sensor, 9 to 11 ... Similarly, light receiving portion, 26, 27 ... switching switch, 28 ... subtraction circuit, 29 ... latch circuit, 30
... Paper color detection sensor light emitting circuit, 31 to 33 ... Delay circuit, 34 ... Paper position detection sensor circuit

Claims (1)

[Claims] 1. A detection means for detecting that a recording medium has been inserted into an apparatus, and color processing for the input color image signal so as to record a color visible image according to the input color image signal on the recording medium. A color processing means for performing a color recording means for recording a color visible image corresponding to the input color image signal color-processed by the color processing means, and an achromatic high-reflecting material provided in a conveyance path of the recording medium, A plurality of light receiving elements each having a wavelength sensitivity characteristic different from that of the light emitting element provided on the side opposite to the achromatic color highly reflective material with respect to the transport path, in relation to the detection of the detecting means of each of the plurality of light receiving elements Retrieval means for retrieving the output Control means for controlling the color processing state of the color processing means on the basis of the respective outputs of the plurality of light receiving elements, which have different wavelength sensitivity characteristics, retrieved by the retrieving means Color Shirushiutsushi apparatus characterized by having.