JPH03277569A - Color printer - Google Patents

Abstract

PURPOSE:To ensure constantly unchanged and satisfactory color reproducibility for recording sheets in different colors by providing a color sensor which detects the color of a recording sheet and a calculation means which corrects an image signal to be recorded on the recording sheet based on an output signal from the color sensor. CONSTITUTION:Primary color image data VD of RGB table color group is entered in units of frame to frame memory 10 from a source such as a TV image receiver and primary image data of a single recording unit R.G.B. is read to be supplied to a color correction circuit 12. The color correction circuit 12 subtracts recording sheet color decomposition data R0, G0, B0 from primary color image data R.G.B. to be recorded and corrects the latter. Primary color image data segments R1, G1, B1 are converted to density data segments Y, M, C of YMC table color group by a color signal conversion circuit 14. The density data segments Y.M.C. receives cloudiness correction process on an ink ribbon using a color masking circuit 16 and then the processed data segments are sent to a thermal head 18. As a result, a color image which has received correction processing on the color of a recording sheet 22 and the cloudiness of an ink ribbon is recorded on the recording sheet 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color printer such as a color video printer.

[Prior Art] In a color printer, image data in an RGB color system inputted from a source such as a television receiver or a VTR is converted into density data in a YMC color system, and an ink ribbon, etc. is printed according to this density data. By multiple-transferring each color material (yellow magenta, cyan) onto the recording paper, the colors of the original image are expressed on the hard copy.

However, the color reproducibility of images printed by conventional color printers was not very good. It has been pointed out that the reason for this is that the colors of general coloring materials are not pure Y, M, and C, but contain some turbidity. For example, a yellow ink ribbon contains some magenta and cyan components, a magenta ink ribbon contains some yellow and cyan components, and the same is true for cyan ink ribbons. In this way, because the coloring material is cloudy, even if the three primary colors (Y, M, C) are multiple-transferred on the recording paper with a mixing ratio that corresponds to the density data, the mixed color (the color of the recorded image) ) will not produce colors that are faithful to the original image.

Conventionally, therefore, the turbidity component of the coloring material has been corrected by once applying color masking processing to the data.

[Problems to be Solved by the Invention] However, even if the turbidity of the color material is corrected by color masking processing as described above, there is a problem that subtle differences in color reproducibility will appear if the colors differ depending on the recording paper. Ta. In other words, in general, the color of recording paper is not pure white, but contains some other color components, and if the color components differ depending on the recording paper, even if the same amount and proportion of the same coloring material is transferred, , the color of the image on each recording sheet will be different.

The present invention has been made in view of such problems, and an object of the present invention is to provide a color printer that always achieves constant and good color reproducibility for recording paper of different colors.

[Means for Solving the Problems] In order to achieve the above object, the color printer of the present invention includes a color sensor that detects the color of recording paper, and an image signal to be recorded on the recording paper as an output signal of the color sensor. Therefore, the present invention is configured to include calculation means for correction.

[Function] The output signal of the color sensor represents the color of the recording paper. Therefore, if the color of the recording paper is not pure white but contains a slight texture component, a corresponding IN sensor output signal will be obtained. The calculation means then performs a correction calculation such as subtracting the value of the sensor output signal from the image signal to be recorded. The image signal corrected by the calculation means is subjected to predetermined processing and then supplied to the head, and the coloring material is transferred from the head onto the recording paper via an ink ribbon or the like.

The amount of color material does not correspond exactly to the original image signal, but when it is combined with the color components of the recording paper, the color of the recorded image corresponds to the color of the original image. It becomes what it is.

Embodiment FIG. 1 shows the circuit configuration of a color printer according to an embodiment of the present invention.

The thermal head 18 receives yellow data Yl and magenta data amount 1 from the color masking circuit 16. / Take Anne's data CI one frame at a time and write it on recording paper 22.
Prints are sequentially layered on top using ink ribbons of each color,
Record color images.

In this embodiment, prior to the recording operation on each recording paper 22, the color of the recording paper 22 is detected by the COD color sensor 24. The three primary color signals R', G', B'' output from the sensor 24 are amplified by the amplifier circuit 26, and then sent to the A/D converter 28 to receive the di-notal signals Re, GO, B''.
It is converted into O and launched into the launch circuit 30 at a predetermined timing.

In this way, the color separation data RO representing the colors of the recording paper 22,
GO and BO are applied to the color correction circuit 12.

On the other hand, the frame memory 10 stores primary color image data VD in the RGB color system from a source (not shown) such as a television receiver.
(R, G, B) are input one frame at a time, and from there
Primary color image data R for a recording unit (for example, 1 line),
G and B are read out and applied to the color correction circuit 12.

This color correction circuit 12 consists of a subtraction circuit, and converts the primary color image data R, G, B to be recorded into recording paper color separation data RO.
, GO, BO, the former is corrected by the latter. In this case, an appropriate coefficient may be added. Examples of the correction processing according to this embodiment are shown in FIGS. 2 to 4. For example, for each pixel dot, the values of the primary color image signals R, G, B to be recorded are CO)1,80H,BO)1 (Figure 2), and the recording paper color separation data R(1,GO,B( When the value of l is 01H, 01LOO1 (Fig. 3), by subtractive correction as described above, B OH, 5Fil, 80H
Primary color image data R1, Gl, Bl having the values of are obtained (FIG. 4).

Primary color image data R1, G output from the color correction circuit 12
I and Bl are converted into data Y, M, and C once in the YMC color system by the color signal conversion circuit 14.

Then, the density data Y, M, and C are sent to the thermal head 18 after being processed in the color masking circuit 16 to correct the turbidity of the ink ribbon. As a result, a color image is recorded on the recording paper 22 by compensating for the color of the recording paper 22 and the turbidity of the ink ribbon.

The control unit 20 outputs a synchronization signal 5 corresponding to the image data VD.
ync to control writing and reading of the frame memory 10, as well as a color correction circuit 129, a color signal conversion circuit 14. Color masking circuit 16. Thermal head 181 A/D
Required timing signals, clock signals, etc. are supplied to the converter 28 and latch circuit 30.

Although the above embodiment was a thermal color printer, the present invention is also applicable to other recording methods such as an inkjet method.

[Effects of the Invention] By having the above-described configuration, the present invention provides the following effects.

The color of the recording paper is detected by a color sensor, and the image to be recorded on the recording paper is corrected according to the sensor output signal, so even if the color varies depending on the type and type of recording paper, the color is always constant. It is possible to obtain color prints with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main circuit configuration of a color printer according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of the embodiment. 10... Frame memory, 12... Color correction circuit, 14... Color signal conversion circuit, 16... Color masking circuit, 18... Thermal head, 20... Control Part, 22... Recording paper, 24... CCD color sensor.

Claims (1)

[Claims] A color printer comprising: a color sensor that detects the color of recording paper; and a calculation means that corrects an image signal to be recorded on the recording paper according to an output signal of the color sensor.