JP3390540B2 - How to improve the writing performance of thermal recording paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the writability of heat-sensitive recording paper for heat recording.

[0002]

2. Description of the Related Art Thermal recording paper such as color thermal recording paper is
Cyan thermosensitive coloring layer, magenta thermosensitive coloring layer on the support,
A yellow thermosensitive coloring layer and a protective layer are sequentially layered. By applying heat energy corresponding to each thermosensitive coloring layer, the thermosensitive coloring layer is selectively colored and a full-color image is formed by using optical fixing together. The heat can be recorded directly. The surface of the color thermosensitive recording paper is made smooth by the protective layer.

On the other hand, as a print mode of a video printer, a full-size mode for printing one frame of a video image on almost the entire surface of, for example, an A6 size recording paper, and a reduced video image for printing on the upper half of the recording paper and post There is a postcard mode to create cards. In this postcard, the lower half on which no video image is recorded is used as a writing area in which greetings and the like are written by hand after printing.

[0004]

However, since the writing area of the postcard and the blank portion of the print made in the full size mode have good smoothness, the writing ability with a pen or pencil of water-based or oil-based ink is poor. However, there is a problem that it is difficult to write, and if the written character or the like is rubbed with a finger, it will be blurred or erased.

It is an object of the present invention to provide a method for improving the writability of a thermosensitive recording paper in which the writability is improved in the writing area and the blank area.

[0006]

In order to achieve the above object, the present invention is applied with a thermal energy of a predetermined level or higher.
It has a thermosensitive coloring layer that develops color by
The heat-sensitive recording paper provided with is divided into a heat- sensitive image recording area and a writing area, and when recording an image in the heat-sensitive image recording area with a thermal printer, the heat energy that does not cause the heat-sensitive recording paper to develop color is applied to the writing area, The surface of the is roughened to improve the writability. In addition, almost the entire surface of the thermal recording paper is used as a thermal image recording area, and when recording an image on this, thermal energy that does not cause the thermal recording paper to develop color is applied to the peripheral area (margin area) of the thermal image recording area. The surface is roughened to improve the writing performance.

[0007]

According to the present invention, since the surface around the writing area or the image recording area of the thermal recording paper is roughened, writing becomes easy, and ink bleeds even when rubbed after writing, or written characters are written. Etc. do not disappear.

[0008]

EXAMPLE FIG. 2 shows a color thermosensitive recording paper used in this example. A color thermosensitive recording paper 1 is a cyan thermosensitive coloring layer 3 on a support 2 and a magenta having an optical fixing property to an ultraviolet ray of 365 nm. A thermosensitive coloring layer 4, a yellow thermosensitive coloring layer 5 having a light-fixing property to ultraviolet rays of 420 nm, and a transparent protective layer 6 are sequentially laminated. The thermosensitive coloring layers 3 to 5 are arranged in the order of thermal recording. When the recording order of each color is changed, the order of the thermosensitive recording layers 3 to 5 is changed accordingly. A single thermosensitive coloring layer may be provided to use thermosensitive recording paper on which a monochromatic image is recorded.

FIG. 3 shows the coloring characteristics of the thermosensitive coloring layers 3-5. In this color thermosensitive recording paper 1, the yellow thermosensitive coloring layer 5 has the lowest coloring thermal energy, and the cyan thermosensitive coloring layer 3 has the highest coloring thermal energy. In the case of thermally recording the yellow pixel, the thermal energy obtained by adding the gradation thermal energy Egy to the bias thermal energy Eby for yellow is applied to the color thermal recording paper 1. This bias heat energy Eby is applied to the yellow thermosensitive coloring layer 5
Is thermal energy immediately before the color is developed and is applied to the color thermosensitive recording paper 1 during the bias heating period at the start of recording one pixel. The gradation expression heat energy Egy is determined according to the color density of the pixel to be recorded, that is, the gradation level of yellow, and is applied to the color thermosensitive recording paper 1 during the gradation expression period following the bias heating period. Since the same applies to magenta and cyan, the symbols Ebm,
Only Egm, Ebc, and Egc are attached.

An opaque high-quality paper is used as the support 2, and a transparent polyvinyl alcohol (PVA) -based material is used as the protective layer 6. The color heat-sensitive recording paper 1 is protected by a protective layer 6 when heat energy is applied from a thermal head 25 described later during heat recording.
Is slightly softened by heat energy and then hardened, so that the surface of the protective layer 6 is roughened and fine irregularities are generated. Due to these fine irregularities, it is possible to write letters reliably with a pencil or pen. It should be noted that this unevenness hardly affects the appearance of the image.

The heating for improving the writability may be performed during recording of a yellow image, during recording of a magenta image, or during recording of a cyan image. When the surface of the protective layer 6 is roughened at the time of recording a yellow image, thermal energy that does not cause the yellow thermosensitive coloring layer 5 to develop color, for example, thermal energy equal to or lower than the bias thermal energy Eby for yellow is used. By using the yellow Baice heat energy Eby just before color development, a special circuit is not required, and it can be easily performed.

At the time of recording a magenta image, the heat energy Ebm for magenta is less than or equal to the heat energy Ebm for magenta. In this case, in order to prevent yellow coloration, it is necessary to heat the yellow thermosensitive coloring layer 5 to the portion where the light is fixed. Similarly, a surface treatment may be performed at the time of recording a cyan image.

The color thermosensitive recording paper 1 has an A6 size shape, and in the full size mode, a full size video image having an aspect ratio of 3: 4 is recorded on almost the entire surface. In the post card mode, as shown in FIG. 1, almost half of the color thermosensitive recording paper 1 is used as an image recording area (heat sensitive image recording area) and the other half is used as a writing area. The image recording area has about 1 full size
A half size video image is recorded in / 2 size in which the orientation of the video image is rotated 90 degrees with respect to the full size orientation. Nothing is recorded in the writing area, and it is used as a space for writing characters such as greetings after printing.

In FIG. 4, which shows an outline of a thermal recording type color video printer embodying the present invention, a video signal of a video image reproduced by a video player, a video camera or the like is inputted to an input terminal 10. The video signal is sent to the Y / C separation circuit 11 via this input terminal 10.

The Y / C separation circuit 11 separates the video signal into a luminance signal (Y) and a chrominance signal (C) and sends it to the decoder 12. The decoder 12 has a luminance signal (Y) and a color signal (C).
And are converted into three primary color signals of yellow, magenta, and cyan and sent to the A / D converter 13. The A / D converter 13 samples each color signal and converts it into, for example, 8-bit 3-color image data for each color, and sends the obtained 3-color image data to the image memory 14 and the switch 15.

The image memory 14 is composed of three frame memories for yellow, magenta, and cyan which store image data of three colors independently for each one frame. Under the control of the memory controller 16, each image data of each color is stored. Write and read operations.

The memory controller 16 is the image memory 1
The image data is written to and read from the data of No. 4. When the full size mode is selected, the memory controller 16 sets the pixels arranged in the vertical direction on the image memory 14, that is, the pixels arranged in the vertical direction (vertical direction) of the video image as one line when reading at the time of printing. The image data of the color to be printed is read line by line from the left side to the right side of the image memory 14 (hereinafter, this is referred to as full size reading). Further, when the post card mode is selected, the memory controller 16 should print the pixels arranged in the horizontal direction on the image memory 14 as one line from the upper side to the lower side of the image memory 14 line by line. The color image data is read while being thinned out (hereinafter referred to as postcard reading).

The memory controller 16 is the image memory 1
By changing the reading direction of the pixels lined up in 4, the vertical / horizontal conversion of rotating the direction of the video image by 90 degrees is performed, and by thinning and reading, the video image is reduced to about 1/2 size. After freezing, the memory controller 16
Image data is read from the image memory 14 in the same manner as when printing. At this time, the image data of three colors is read from the image memory 14. Image memory 14
The image data read from is sent to the switch 15 at the time of monitoring, and the first line memory 17 at the time of printing.
Sent to.

The switch 15 is an A / D switch for image input.
Each color image data from the converter 13 is sent to the monitor system D / A converter 19, and after freezing, each color image data from the image memory 14 is sent to the monitor system D / A converter 19. Monitor system is D / A converter 1
9, an encoder 20 and a D / A converter 19
Each color image data is converted into each color signal by the encoder 2
At 0, each color signal is converted into a video signal. Encoder 2
0 sends the video signal to the output terminal 21. A monitor (not shown) such as a home TV is connected to the output terminal 21, and a video image being input to the video printer or a video image captured by the video printer can be observed by the monitor.

The bias data generator 22 generates one line of bias data for generating the bias heat energy of each color in each heating element 25a (see FIG. 1) of the thermal head 25, and stores it in the second line memory 18. send.

Image data for one line is written in the first line memory 17, and one line image is written in the second line memory 18.
Bias data for the line is written. Selector 2
When recording one line of a video image in the image recording area, first, the second line memory 18 is first connected to the head drive unit 2.
4 and then the first line memory 17 is switched to be connected to the head drive unit 24. Further, when the thermal head 25 faces the writing area, the second line memory 18 is connected to the head drive unit 24.

The head drive section 24 drives the thermal head 25 based on the image data or the bias data. As shown in FIG. 1, in the thermal head 25, a large number of heating elements 25a are arranged in a line in the main scanning direction, and the color thermal recording paper 1 wound around the outer periphery of the platen drum 26 is connected to the platen drum 26. By feeding each line in the sub-scanning direction by the rotation of, the thermal recording is performed on the color thermosensitive recording paper 1 line by line.

When recording a video image, the head drive section 24 sends one or a fixed number of bias heating drive pulses to each heating element 25a based on the bias data during the bias heating period. In the subsequent gradation heating, as many gradation heating driving pulses as the number corresponding to the image data are sent to each heating element 25a. The thermal energy generated by these driving pulses is applied to the color thermosensitive recording paper 1, and the yellow thermosensitive coloring layer 5 develops a color at a density corresponding to the image data, for example. Further, when recording the yellow image, when the thermal head 25 faces the writing area, the head drive unit 24 sends a bias heating drive pulse for yellow to each heating element 25a based on the bias data. , The bias heat energy Eby alone is applied to the color thermal recording paper 1. The pulse widths of the bias heating drive pulse and the gradation heating pulse differ depending on the color to be printed.

As shown in FIG. 4, the platen drum 26
Is rotated in the direction of the arrow in the figure by a motor 28 driven by a driver 27. A keyboard 30 is connected to the control unit 29, and by operating the keyboard 30, a freeze instruction and a print instruction can be issued. By operating the keyboard 30, either the full-size mode or the postcard size mode can be selected. The control unit 29 controls each unit.

An ultraviolet lamp for yellow and an ultraviolet lamp for magenta are arranged on the outer periphery of the platen drum 26, but they are omitted in FIG. The yellow ultraviolet lamp radiates ultraviolet rays having an emission peak of 420 nm to optically fix the yellow thermosensitive coloring layer 5. The magenta ultraviolet lamp radiates ultraviolet rays having an emission peak of 365 nm to optically fix the magenta thermosensitive coloring layer 4.

Next, the operation of the above configuration will be described.
For example, a video player is connected to the input terminal 10 and a monitor is connected to the output terminal 21. When the video player is set to the reproduction state, the video signal of the reproduced video image is input from the input terminal 10 to the Y / C separation circuit 11, and the Y / C separation circuit 11 outputs the luminance signal (Y) and the color signal (C). Is separated into The luminance signal (Y) and the color signal (C) are converted into three primary color signals of yellow, magenta, and cyan by the decoder 12, and these three primary color signals are sampled by the A / D converter 13 to generate an image of three colors. Converted to data. The obtained image data of each color is sent to the switch 15 and the image memory 14. At this point, the image memory 14
No image data is written to.

Each color image data is sent to the monitor system via the switch 15 and converted into a video signal. This video signal is sent to the monitor via the output terminal 21, and the video image currently being input is displayed. While observing this video image, when the scene to be printed is displayed, the keyboard 30 is operated to give a freeze instruction. The image data of the three colors of the video image for which the freeze instruction is given is written in the image memory 14. Further, in response to this freeze instruction, the video printer enters the monitor state, and the switch 15 is switched to send the image data of the three colors from the image memory 14 to the monitor system.

When the image data of three colors for one frame is written in the image memory 14, the memory controller 16 reads the image memory 14 line by line from the upper side to the lower side.
The read three-color image data is sent to the monitor system via the switch 15, converted into a video signal, and then sent to the monitor via the output terminal 21. The monitor displays the video image of the frame captured by the video printer. Observe the video image displayed on this monitor to see if it is the desired video image.

When printing the captured video image, the print mode is selected with the keyboard 30 and then the print instruction is given. For example, when a print instruction is issued after selecting the postcard mode, the memory controller 16 starts postcard reading and reads the image data of the color to be printed from the image memory 14.
In this reading, each color image data is read line by line in the horizontal direction, and is read while being thinned out to reduce the size.

Further, the color thermosensitive recording paper 1 is conveyed from, for example, a paper feeding cassette in accordance with a print instruction, and is wound around the platen drum 26. Then, the recording start end of the color thermosensitive recording paper 1 is set so as to face the thermal head 25.

First, the yellow image data of the first line is fetched from the image memory 14, and the image data for one line is written in the first line memory 17. Also,
The bias data generation unit 22 generates bias data for one line, and uses this bias data in the second line memory 1
Write to 8. Further, the selector 23 is switched to connect the second line memory 18 and the head drive unit 24.

The head drive unit 24 uses the second line memory 1
The bias data of No. 8 is taken out, and a bias heating drive pulse is generated based on this bias data. Each heating element 25a of the thermal head 25 is driven by this bias heating drive pulse, and bias heat energy Eby for yellow is generated to perform baice heating. When this bias heating is completed, the selector 23 is switched to connect the first line memory 17 and the head drive unit 24. The head drive unit 24 takes out the yellow image data of the first line from the first line memory 17 and generates a gradation heating drive pulse. Each heating element 25a is driven by this gradation heating drive pulse to generate gradation expression heat energy Egy. These bias heat energy Eby and gradation expression heat energy Eg
y is given to the color thermosensitive recording paper 1, the yellow thermosensitive coloring layer 5 develops color, and the first line of the yellow image is thermally recorded on the color thermosensitive recording paper 1.

After the yellow image of the first line is recorded, the platen drum 26 rotates and the color thermosensitive recording paper 1 becomes 1
Lines are sent. Further, the selector 23 is switched to connect the second line memory 18 and the head drive unit 24. After this switching, the head driving unit 24 takes in the bias data of the second line memory 18 and causes each heating element 25a to generate the bias thermal energy Eby. On the other hand, by the time the bias heating is completed after the recording of the first line is completed, the yellow image data for one line of the second line is read out from the image memory 14,
It is written in the line memory 17. As in the case of the thermal recording on the first line, the selector 23 is switched after the bias heating is completed, and the first line memory 17 and the head drive unit 2 are switched.
4 and 4 are connected. Based on the yellow image data of the second line, the head drive unit 24 determines that each heating element 25
The gradation expression thermal energy Egy corresponding to the image data is generated in a. These thermal energies are applied to the color thermosensitive recording paper 1 to thermally record the second line of the yellow image.

The third and subsequent lines are also heat-recorded on the color thermosensitive recording paper 1 line by line in the same manner. In this way, the yellow image is thermally recorded on the image recording area of the color thermosensitive recording paper 1.

When the thermal recording of the yellow image is completed, the thermal head 25 faces the writing area of the color thermosensitive recording paper 1. This can be known from the feed amount of the color thermosensitive recording paper 1 from the start of recording. When the thermal head 25 faces the writing area, the selector 23 is moved to the second position.
Control is performed so that only the line memory 18 is selected. As a result, the selector 23 enters a state in which the second line memory 18 and the head drive unit 24 are connected.

After the selector 23 is switched, the head drive section 24 takes in the bias data of the second line memory 18 and drives the thermal head 25 based on this bias data. The head drive unit 24 supplies the bias heat energy Eby for yellow to each heating element 25a.
Cause to. The bias heat energy Eby is applied to the first line of the writing area of the color thermosensitive recording paper 1. After the bias heat energy is applied to the first line of the writing area, the platen drum 26 rotates and the color thermosensitive recording paper 1 is fed by one line. Only the bias heat energy Eby is given to the first line of the writing area, and the thermosensitive coloring layers 3 to 5 do not develop color,
The protective layer 6 is once softened and then cured, so that the surface thereof is roughened and fine irregularities are formed.

The head driving section 24 extracts the bias data from the second line memory 18 again and outputs the bias data to each heating element 2.
Bias heat energy Eby is generated in 5a, and this bias heat energy Eby is applied to the second line of the writing area. Similarly, for the entire writing area,
Bias heat energy Eby is applied line by line. In this manner, the bias thermal energy Eby is applied to the entire writing area of the color thermosensitive recording paper 1 to roughen the surface and form fine irregularities. The bias thermal energy Eb is set to the position of the last line of the writing area.
When y is given, the thermal recording of the yellow image ends.

After the thermal recording of the yellow image, the color thermosensitive recording paper 1 is irradiated with ultraviolet rays of 420 nm to optically fix the yellow thermosensitive coloring layer 5.

After the yellow thermosensitive coloring layer 5 is optically fixed,
The platen drum 26 is continuously rotated, and the recording start end of the color thermosensitive recording paper 1 is set again at a position facing the thermal head 25. After this, thermal recording of the magenta image is started. Even in the thermal recording of the magenta image, the magenta image data is read from the image memory 14 line by line and written in the first line memory 17. The selector 23 includes a second line memory 18 and a first line memory 17
Are alternately selected to connect to the head drive unit 24. The head drive unit 24 takes in bias data and magenta image data for each line, drives the thermal head 25, and thermally records a magenta image line by line in the image recording area. At this time, the head drive unit 24 generates the bias heat energy Ebm for magenta for each heating element 25a based on the bias data during the bias heating period, and responds to the magenta image data during the gradation expression heating period. The gradation expression heat energy Egm is generated.

In this way, the bias heat energy Ebm for magenta and the gradation expression heat energy Egm are applied to the color thermosensitive recording paper 1 to cause the magenta thermosensitive coloring layer 4 to develop a color, thereby recording a magenta image line by line. In the thermal recording of the magenta image, when the thermal head 25 faces the writing area, the color thermal recording paper 1 is continuously fed without applying heat energy to the writing area. After thermal recording of the magenta image, the color thermal recording paper 1 has 365
Then, the magenta thermosensitive coloring layer 4 is photofixed.

After optically fixing the magenta thermosensitive coloring layer 4,
When the platen drum 26 is continuously rotated and the recording start end of the color thermal recording paper 1 faces the thermal head 25,
The thermal recording of the cyan image is started, the bias thermal energy Ebc for cyan and the gradation expressing thermal energy Egc are given to the image recording area, and the cyan image is thermally recorded line by line on the cyan thermosensitive coloring layer 3. Even at this time, no heat energy is given to the writing area. Further, optical fixing is not performed on the cyan thermosensitive coloring layer 3. When the thermal recording for cyan is completed, the platen drum 2
6 is continuously rotated, and the color thermosensitive recording paper 1 is ejected from the video printer.

In the print made in the post card mode, as shown in FIG. 1, a video image is recorded in the image recording area of the color thermosensitive recording paper 1, and nothing is recorded in the writing area indicated by hatching in the figure. It has not been done. Since the surface of the writing area is heated by the bias heat energy Eby to be roughened and fine irregularities are formed, it is possible to easily write with a water-based ink, an oil-based ink, a pencil, or the like. Dotted characters, etc. do not easily bleed and do not disappear even if they are rubbed with a finger or the like.

In the above embodiment, nothing is printed in the writing area, but as shown in FIG. 5, a title image may be heat-recorded in the writing area by using, for example, the title compositing function of a video printer. In this case, heat energy that does not cause each of the thermosensitive coloring layers 3 to 5 to give a color is applied to a portion of the writing area where the title image is not recorded to roughen the surface.

In the above embodiment, when the color thermosensitive recording paper 1 is viewed vertically, the video image is recorded in the upper half and the lower half in which no image is recorded is the writing area in the post card mode. However, when recording a video image in the full size mode, an example of improving the writability of the margin will be described. The same parts as those in the above embodiment are designated by the same reference numerals.

In the embodiment shown in FIG. 6, a part of a video image is cut by trimming to improve the writing property of this part. With the lower side of the video image cut, the image data of the color to be printed is read out from the image memory 14, and this image data is stored in the first line memory 17
Written in. In addition, image data indicating the color density (gradation level) “0” is written in the first line memory 17 for the portion where the video image is cut.

For example, when thermally recording a yellow image, the head drive unit 24 generates bias heat energy Eby in each heating element 25a based on the bias data of the second line memory 18, and the first line memory 18 is generated. Gradation expression thermal energy E based on 17 yellow image data
gy is generated in each heating element 25a. These thermal energies are given to the color thermosensitive recording paper 1. However, since the image data indicates the gradation level "0" in the heating element 25a corresponding to the portion of the video image cut by trimming, the gradation expression heat energy Egy.
Does not occur. That is, the portion (margin portion) of the color thermosensitive recording paper 1 corresponding to the portion cut by trimming.
The yellow thermosensitive coloring layer 5 does not develop color, but the surface is roughened to form fine irregularities.

As described above, the magenta image and the cyan image are recorded line by line. In this embodiment, every time each color is thermally recorded, the bias heat energy of each color is applied to the color thermal recording paper 1 in the blank area. For example, at the time of thermal recording of a magenta image, the bias thermal energy Ebm for magenta, which is higher than the thermal energy (Eby + Egy) for coloring yellow, is applied to the color thermosensitive recording paper 1, but the yellow thermosensitive coloring layer 5 is optically fixed. Because
The yellow thermosensitive coloring layer 5 in the margin portion is not colored. Therefore, the surface of the blank area can be roughened to form fine irregularities. When the magenta and cyan images are thermally recorded, the bias data for which the bias heat energy is “0” is written in the second line memory 18 for the portion to be trimmed, and the magenta and cyan baisices are written. The heat energy may not be applied.

As shown in FIG. 6, the print thus created has a trimmed video image recorded therein, and the margin portion (hatched portion in the figure) below the video image is Writability is improved. The part to be cut by trimming is not limited to the lower side of the video image, but the left side and the right side. It may be the upper part.

The embodiment shown in FIG. 7 is designed to create a blank area with good writing performance without trimming the video image. The thermal head 50 used in this embodiment has a long length and a large number of heating elements 50a. The central portion of the thermal head 50 is driven based on the bias data and the image data to record a video image. Further, at both ends of the thermal head 50, only bias heating is performed, and the surface of the blank portion shown by hatching is exposed, so that the writability is improved.

[0050]

As described above in detail, according to the method for improving the writability of the thermosensitive recording paper of the present invention, the heat energy which the thermosensitive coloring layer does not develop is applied to the surface of the writing area or the periphery of the image. Since the ink is roughened, writing with ink, pencil, etc. becomes easy, and the written letters, etc. do not smear or disappear, and the writing performance is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a postcard created in a postcard mode.

FIG. 2 is an explanatory view showing the layer structure of color thermosensitive recording paper.

FIG. 3 is a graph showing coloring characteristics of each thermosensitive coloring layer.

FIG. 4 is a schematic diagram of a video printer embodying the present invention.

FIG. 5 is an explanatory diagram showing a postcard in which a title image is heat-recorded in a writing area.

FIG. 6 is an explanatory diagram showing a color thermosensitive recording paper in which a full-size image is trimmed to create a blank portion with good writing properties.

FIG. 7 is an explanatory diagram showing a color thermosensitive recording paper in which blank areas with good writing properties are formed above and below a full-size video image.

[Explanation of symbols]

1 color thermal recording paper 2 support 3-5 Thermosensitive coloring layer 6 protective layer 14 image memory 17,18 line memory 22 Bias data generator 23 Selector 24 Head drive 25,50 Thermal head 25a, 50a heating element

Claims (2)

(57) [Claims] 1. A thermal energy above a predetermined level is applied.
Has a thermosensitive coloring layer that develops color when exposed to heat, protecting the surface
Dividing the heat-sensitive recording paper layer is provided on the writing area as thermal image recording area, when recording an image on a thermal image recording area in a thermal printer, applying heat energy thermal recording paper is not colored writing area, writing A method for improving the writability of a thermal recording paper, characterized by roughening the surface of an area to improve the writability. 2. A thermal energy of a predetermined level or higher is applied.
Has a thermosensitive coloring layer that develops color when exposed to heat, protecting the surface
When recording an image with a thermal printer in the thermal image recording area of the thermal recording paper on which layers are provided, heat energy that does not cause the thermal recording paper to develop color is applied to the peripheral area of the thermal image recording area to roughen the surface of the peripheral area. A method for improving the writability of thermosensitive recording paper, which is characterized by improving the writability.