JPH0465971A - Copying machine provided with uneven density correcting function - Google Patents

Abstract

PURPOSE:To simultaneously remove the uneven density of data and uneven recording density and to easily attain correction corresponding to the replacement of a reader or a recorder or a secular change by providing the copying machine with a means for simultaneously correcting the dispersion of characteristics of the reader and the recorder. CONSTITUTION:A correction group number arithmetic unit 12 executes prescribed arithmetic processing in each recording dot based on an address signal outputted from a counter 11, forms a group number for selecting correction gradation level data D1, stores the group number in a RAM 13, and outputs the group number to an EPROM 14. Since uneven density for recording can be corrected at the time of replacing the recorder or the reader or in accordance with the secular changes of these devices, a copied image of high quality can always be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying machine, and particularly to a copying machine having a function of correcting density unevenness.

[Prior Art] Fig. 8 is shown, for example, in ``Technology for Improving the Image Quality of High-Quality Video Copy'' described in the collection of papers of the 3rd Non-Impact Printing Technology Symposium in 1985, pages 37 to 40. 1 is a block diagram showing a recording density correction device for a conventional copying machine.

In FIG. 8, (11) is a counter that outputs an address signal A1 corresponding to each heating element constituting the thermal head, and (71) is a counter that measures the resistance value of each heating element to obtain a correction coefficient. A computing device such as a personal computer or a minicomputer (72) which determines the group number of each heating element from the value of is a first EPR in which the group number is stored according to the address signal A1.
OM (14) is a second EPROM that stores data for driving the thermal head (corrected gradation level data D2) in correspondence with the set number.

FIG. 9 shows the second EPROM (1
4) is a diagram showing the correspondence between the corrected gradation level data D2 stored in FIG. 4) and set numbers (1 to 16).

Next, the operation of the conventional printer recording density correction device configured as shown in FIG. 8 will be described.

First, the arithmetic unit (71) measures the resistance value of each heating element constituting the thermal head in advance, divides the heating elements into several groups according to the resistance value, and then calculates a correction coefficient. Based on the correction coefficient, set the group number (
1 to 16) and set this as the first EPROM (72).
Write it in. This grouping may be performed by optically measuring the recording density unevenness of the recorded image and based on the measured value.

The counter (11) is connected to a clock generation circuit (not shown).
The address signal A1 corresponding to each heating element is sent to the first EPROM (7).
2) Output to. The first EPROM (72) then uses the address signal A1, that is, the set number (1 to 16) corresponding to each heating element, as the address signal A3 to the second EPROM.
Output to ROM (14).

Based on this set number, the second EPROM (14)
The uneven density data (input gradation level data D,) is corrected and new corrected gradation level data D2 is output to each heating element.

[Problems to be Solved by the Invention] Conventional copying machines cannot eliminate density unevenness that occurs during reading due to variations in the characteristics of the reading device, and since the set number is stored in an EPROM, However, there has been a problem in that it is difficult to change the correction data when replacing the reading device and the recording device or in response to changes over time.

This invention was made to solve these problems, and simultaneously eliminates the density unevenness of data that occurs during reading and the recording density unevenness that occurs during recording, and also improves the reading device and It is an object of the present invention to provide a copying machine with a density unevenness correction function that can easily perform corrections when replacing recording devices or in response to changes over time.

[Means for Solving the Problems] A copying machine with a density unevenness correction function according to the present invention eliminates variations in the characteristics of recording devices such as thermal transfer recording, thermosensitive recording, or light emitting diodes, and of reading devices such as line-type sensors. A calculating means for calculating a set number for selecting corrected gradation level data for driving the recording device by calculating the variation in characteristics for each recording dot; and means for storing the set number. It is something that

[Operation] In the present invention, density unevenness caused by variations in the characteristics of the reading device and density unevenness caused by variations in the characteristics of the recording device are corrected at the same time.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a density unevenness correction circuit of a copying machine with density unevenness correction function according to the present invention. In this FIG. 1, (11) and (14) are equivalent to those shown in the conventional example of FIG. 5, so their explanation will be omitted here.

(12) is a correction set number for creating a set number for selecting the corrected gradation level data D1 by performing predetermined arithmetic processing for each recorded dot based on the address signal output from the counter (11). The arithmetic unit (13) is a RAM that stores the set number and outputs it to the EPROM (13).

FIG. 2 is an external view of the main body of the copying machine, where (21) is the reading section at the top, and (22) is the reading section (21).
), a removable lid attached to cover the (23)
is a card holder attached to the inside of this II (21), and (24) is a special card for correction, one side is white and the other side is gray, and the card holder ( 21). (25) is a glass plate that covers the reading section (21), (26) is a pair of paper fixing holders attached to two sides of this glass plate (25), and (27) is a glass plate that covers the reading section (21). A marker lamp that emits transmitted light in order to set a recorded sample of a copied image in a predetermined position, and is connected to the reading section (2).
It is provided in close contact with the lower part of the glass plate (25) of 1), and is about the same size as a one-dot recording, or smaller in size. (28) is an operation panel attached to the side, on which various operation switches are arranged. (29) is a correction mode/normal mode changeover switch located on this operation panel, (30) is a start switch to start reading the recorded sample, and (31) is a RAM (13) This is a correction reset switch that changes the stored content to initial data.

Figure 3 shows the paper fixing press plate (26) in Figure 2 above.
), in which (26a) is a paper fixing presser plate support shaft for fixing the paper fixing presser plate (26).

FIG. 4 is a diagram for explaining the relationship between the resolutions of the reading device and the recording device. In this Figure 4,
(41) is a line type CCD sensor, (42) is a CCD sensor element on this line type CCD sensor (41), (
43) is a line type thermal head, and (44) is a heating element on this line type thermal head (43).

Next, the operation of the copying machine with density unevenness correction function configured as described above will be explained.

First, attach the correction card (24) to the card holder (23) with the gray side facing up.
) close. After setting the correction mode/normal mode changeover switch (29) to normal mode and setting the memory contents of the RAM (13) to initial data using the correction reset switch (31), copying is started, and the reading device and recording device are Obtain a recorded sample of a copied image in which density unevenness occurs due to variations in the characteristics of the vise.

Next, hold the correction card (24) with the white side facing up, and place the previously obtained recording sample on both sides of the line where recording will start and the marker. It is set in a predetermined position by the transmitted light of the lamp (27) and fixed with the paper fixing press plate (26).

Next, the operation of performing correction using the recording sample fixed to the reading section (21) as described above will be explained based on the flowchart of FIG.

Switch the correction mode/normal mode selector switch (29) to correction mode and turn the start switch (28) to O.
When set to N, copy image data (original gradation level data D0) is read from the recorded sample.

The correction set number calculation device (12) calculates the resolution R of a reading device such as a CCD element (42) on a CCD sensor (41) and a thermal head (43).
If the resolution W of the recording device such as the heating element (44) above is equal, this original gradation level data D. For each read line, the calculation according to equation (1) is performed.

N, 2 set number Line: Number of read lines j: Number of dot directions i: Number of tine directions data [i] [j: data of i line, j dot k: coefficient and obtained by calculation of equation (1) The value is a set number N for selecting the corrected gradation level data D1.

Furthermore, as shown in Fig. 3, the resolution R of the reading sensor is
and the resolution W of the recording device are different, and between the resolution R of the reading sensor and the resolution W of the recording device (
2) Original gradation level data D if the relationship as shown in the formula holds true. An average is taken for each n number of values, and each average value is treated as one data and the calculation according to equation (1) is performed.

R=nXW, (n is an integer of 2 or more)---(2>The set number thus obtained is stored in the RAM (13), and the correction of density unevenness is completed.

Next, select the correction mode/normal mode switch (29).
) in normal mode and copying, the set number will be changed to RAM (
13) to the EPROM (14), and this set number and input gradation level data D. Corrected gradation level data D1 is output based on.

In the above embodiment, a card holder (23) is provided for the correction-only card (24), but as shown in FIG. 6, a card belt (51) is provided instead of the card holder (23). The same effect can be obtained even if the roller (51) is driven manually or by a motor to replace the white side and the gray side of the correction card (24).

In addition, as shown in Fig. 7, a correction dedicated card (24)
The same effect can be obtained by preparing two cards, a white card (62) and a gray card (61), winding one of them around a winding roller (63), and pulling it out when used.

[Effects of the Invention] As explained in detail above, the present invention calculates and processes the variations in the characteristics of the recording device in the recording section and the variations in the characteristics of the reading device in the reading section for each recording dot to improve the recording device. By providing a calculation means for creating a set number for selecting corrected gradation level data to be driven; and a rewritable storage means for storing this set number, it is possible to replace the recording device and the reading device, or Since density unevenness during recording can be corrected in accordance with aging of these devices, it is possible to always obtain high-quality copied images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the correction circuit of the present invention, FIG. 2 is a diagram for explaining the external mechanism of the above embodiment, and FIG. 3 is a block diagram showing an embodiment of the correction circuit of the present invention. A detailed diagram showing the holding mechanism, FIG. 4 is a diagram for explaining the relationship between the resolutions of the reading device and the recording device, FIG. 5 is a flowchart diagram for explaining the correction operation, and FIG. 6 is a diagram for explaining the belt. FIG. 7 is a diagram for explaining the pull-out type correction card exchange mechanism, FIG. 8 is a block diagram showing the correction circuit, and FIG. 9 is a diagram for explaining the correction circuit. FIG. 7 is a diagram showing the correspondence between corrected gradation level data and set numbers. In the figure, (11) is a counter, (12) is a correction set number calculation device, (13) is a RAM, and (14) is an EPROM. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (3)

[Claims] (1) In a copying machine equipped with a recording section that performs thermal transfer recording, thermal recording, or recording using a light emitting diode, and a reading section that performs reading using a line sensor; a reading device in the reading section; A copying machine with a density unevenness correction function, comprising: a correction means for simultaneously correcting variations in characteristics of a recording device in a recording section; (2) The correction means calculates the variation in the characteristics for each recorded dot to create a set number for selecting corrected gradation level data for driving the recording device; A copying machine with a density unevenness correction function according to claim 1. (3) The correction means adjusts the resolution R (dpi) of the reading device and the resolution W (dpi) of the recording device.
The density unevenness correction function according to claim 2, wherein a set number is created by performing arithmetic processing so that the relational expression R=nW (dpi), (n is an integer) holds between Copy machine with attached.