JPS6135067A - Picture forming method - Google Patents

Abstract

PURPOSE:To expand the dynamic range with use of a photosensitive material having a wide exposure region by using a light shut-off type liquid crystal panel (at voltage application) to set the light transmitting state in response to a picture signal thereby obtaining a smooth picture with abundant intermediate tone. CONSTITUTION:An RGB filter 4 is arranged between a linear light source 2 of a color printer 1 and a color-sensitive material 3 on which an exposure light L from the light source 2 and it is driven by a driver, and a perture 5 eliminating the scattered light sensitivity by a slit 5a is provided in front of the light source 2. Further, a correction filter 6 applying color correction is arranged between the aperture 5 and the filter 4. A material having an under-cut characteristic expressing the intermediate tone is used for the photosensitive material 3 and a liquid crystal panel 9 is arranged on the photoelectric material 3. A light shut type at voltage application formed with a liquid crystal shutter array or a matrix is used for the panel 9. A pulse shorter than the falling time of the liquid crystal is applied continuously to the liquid crystal ahead the exposure to shut the light and then a voltage in response to the picture signal is applied to set the light transmission state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method in which an image is reproduced by a liquid crystal array or matrix driven based on image information and the image is recorded on a photosensitive material, and in particular, a rich range of intermediate tones can be obtained. The present invention relates to an image forming method as described above.

(Technical Background and Prior Art of the Invention) For example, as shown in Japanese Patent Application Laid-Open No. 57-160667, a liquid crystal array is formed by arranging many sets of transparent electrodes on the surface of a photosensitive material that is irradiated with exposure light. Alternatively, a liquid crystal matrix (hereinafter collectively referred to as a liquid crystal panel) is arranged, each liquid crystal serving as a pixel of the liquid crystal panel is driven by a signal carrying image information to reproduce an image on the panel, and the image is reproduced by the exposure light. An image forming method is known in which a transmitted image of the image is recorded on a photosensitive material by exposing it to light. On the other hand, liquid crystal panels capable of expressing gradation have already been provided, such as those used in so-called liquid crystal televisions, and if such a liquid crystal panel is used in the above image forming method, halftones can be displayed on the photosensitive material. You can also record existing images.

However, conventional liquid crystal panels capable of expressing gradation can only express about 8 to 16 gradations, and when used in the image forming method described above, smooth image quality cannot be obtained, and especially color images It has been recognized that there is a problem with poor skin color expression during formation.

In view of the above circumstances, the present applicant has already developed an image forming method in which a liquid crystal panel as a light valve is interposed between a photosensitive material and a light source, as described above, in which the driving of the liquid crystal is determined to be shorter than the response time of the liquid crystal. Controlling by using short driving pulses and changing the width or number of the driving pulses according to the image signal,
In this way, we proposed an image forming method using a liquid crystal panel in which a so-called Victorian image can be obtained by exposing an image formed on a liquid crystal panel to a photosensitive material capable of expressing halftones (Japanese Patent Application No. 162909/1983). ),.

However, in the above image forming method, when a liquid crystal of a constant light-blocking type (for example, a parallel Nicol type twisted nematic liquid crystal) is used and the liquid crystal is opened by applying a voltage, the liquid crystal becomes The opening response is relatively fast, and therefore the opening degree of the liquid crystal can be precisely controlled within this opening response time. -The amount of light leaking from nematic liquid crystal is relatively large and varies depending on the wavelength of the light (an example of the characteristics is shown in Figure 3), so as a photosensitive material, the so-called γ (the slope of the straight line part of the characteristic curve) is low and the exposure range is low. It is not suitable for use with wide areas, and if it is necessary to keep the amount of leakage light low when forming color images, it is necessary to switch between liquid crystals suitable for each color of light. There were also some glitches.

(Purpose of the Invention) Therefore, the present invention allows the gradation to be set particularly finely, allows the use of photosensitive materials with a wide exposure range, and further eliminates the need to switch the liquid crystal panel according to each color of light even when forming color images. The object of the present invention is to provide an image forming method using a liquid crystal panel.

(Structure of the Invention) As described above, the image forming method of the present invention involves interposing a liquid crystal panel as a light valve between a photosensitive material and a light source, and using a photosensitive material capable of expressing an image formed on the liquid crystal panel in halftones. In an image forming method that involves exposure to light, a liquid crystal panel that blocks light when voltage is applied is used, and prior to exposure, a pulse voltage shorter than the response time of the liquid crystal is continuously applied to all liquid crystals to direct light from the light source toward the photosensitive material. The invention is characterized in that the voltage application to the descendant liquid crystal is interrupted for a time corresponding to the image signal, and the liquid crystal is set in a light transmitting state during that time.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a printer that records an image using an image forming method according to an embodiment of the present invention. This printer 1
As an example, a color print is formed by a three-color separation method, and includes a line light source 2 that emits white light, and a line light source 2 that emits white light.
Between the color photosensitive material 3 to which the reverse exposure light is irradiated, there is an RGB plate rotatably driven by a drive device (not shown).
A filter 4 is arranged. On the front of the line light source 2,
A diaphragm that removes the diffused light component of the exposure light from the linear light source 2 using the slit 5a! A correction filter 6 is provided between the aperture 5 and the RGB filter 4 for color correction of exposure light. Note that not only a line light source but also a point light source can be used as the light source.

The color photosensitive material is made of a high-sensitivity silver salt photosensitive material that is capable of expressing intermediate tones and has a cutting characteristic as described below, and is supported on a conveyor belt 8 rotated by a drive roll 7. It is designed to be conveyed in the direction of arrow A in the figure. A liquid crystal panel 9 is disposed above the conveyor belt 8 so as to be in close contact with the color photosensitive material 3 on the conveyor belt 8. The liquid crystal panel 9 is of a known so-called array type, and will be briefly described below.

The liquid crystal panel 9, as shown in the side cross-sectional shape in FIG.
It has one transparent horizontal electrode 12 and a large number of transparent vertical electrodes 13 arranged in an array, and on the surfaces of these horizontal electrodes 12 and vertical electrodes 13 there is an alignment film 14 in which nematic liquid crystal molecules are aligned in one direction. 15 is formed. The horizontal electrode 12 and the vertical electrode J3 are arranged in directions perpendicular to each other, as shown in FIG. The alignment films 14 and 15 are arranged facing each other with a gap between them, sandwiching the spacing material 16 disposed at the periphery, and a TN (twisted nematic) film is formed in the gap.
A liquid crystal 17 is sealed, and the spacer 16 is surrounded by a sealing material 18. The above alignment film 14.1
5, the orientation direction of the liquid crystal 170 molecules is determined by the horizontal electrode 12.
, are relatively shifted by 90° on the surface of the vertical electrode 13. Further, a polarizing plate 19 whose polarization axis is aligned with the orientation direction of liquid crystal molecules on the surface of the horizontal electrode 12 is disposed outside the upper glass 10, while a metal mask 20 and a filter 21' are provided outside the lower glass 11 to polarize light. A plate 22 is arranged. The polarization axis of this polarizing plate 22 is 90° with respect to the polarization axis of the polarizing plate 18.
They are shifted to form a so-called orthogonal Nicol type. The above structure is supported by a printed circuit board 23, and a voltage is applied between the horizontal electrode 12 and the vertical electrode 13 via a conductive rubber connector 24.

When no voltage is applied between the electrodes 12 and 13 in the M crystal panel 9, the light passing through the polarizing plate 19 becomes linearly polarized light and enters the layer of liquid crystal 17, and the plane of polarization changes by 90 degrees according to the molecular orientation of the liquid crystal 17. It rotates by 0° and reaches the polarizing plate 22. As mentioned above, the polarization axes of this polarizing plate 22 and the upper polarizing plate 19 are perpendicular to each other, so the polarizing plate 22 is
The light that has reached the polarizing plate 21 passes through the polarizing plate 21. On the other hand, electrode 1
When a voltage that exceeds the threshold voltage to some extent is applied between the electrodes 12 and 12, molecules of the liquid crystal 17 are caused to move between the electrodes 12 and 12 due to the electric field effect.
Change direction by 90 degrees in 13 seconds. Therefore, the upper polarizing plate 18
The light that has passed through reaches the lower polarizing plate 22 without changing its plane of polarization, and is blocked by the polarizing plate 22. In such an array type liquid crystal panel 9, by selecting the electrode to which the entire voltage is applied from among the vertical electrodes 13 arranged orthogonally to the horizontal electrodes 12, the opposing portions 9a of both electrodes 12.13 are Bright area (light transmitting area) and dark area (light blocking area) in units
can be set.

As described above, bright areas and dark areas are set for each opposing portion 9a of both electrodes 12 and 13, and the photosensitive material 3 is moved in the direction of arrow A in FIG.
That is, by moving it in a direction perpendicular to the longitudinal direction of the array type liquid crystal panel 9, a desired image is exposed on the photosensitive material 3.

FIG. 6 shows in detail a liquid crystal drive circuit for driving the liquid crystal panel 9. As shown in FIG. The three color signals of R (red), G (green), and B (blue) are input to the RGB switching circuit 30, and the RGB switching circuit 30, based on the RGB switching clock C1 input from the clock pulse generation circuit 31, Above R1G, B
Switch and output signals sequentially. The signals carrying each color density are subjected to predetermined image processing and color processing in the image processing circuit 32, and then to the line sampling circuit 33, based on the line clock C2 inputted from the clock pulse generation circuit 34, one line, i.e. The image signal for each line is sampled for each pixel column (column for the electrode facing portion 9a) of the array type liquid crystal panel 9, and is digitized in the A/D conversion circuit 35 and stored in a RAM (Random Access Memory).
y) is stored in the line memory 36.

The image signal for each line read from the line memory 36 is input to a liquid crystal driver 40 (integrated with the liquid crystal panel 9) consisting of a shift register 37, a counter 38, and a gate circuit 39, and the shift register 37, the data is extracted for each pixel (facing portion 9a) of the liquid crystal panel 9 based on the data clock C3 inputted from the clock pulse generation circuit 41. A gradation count clock C4 is inputted to the counter 38 from the clock pulse generation circuit 42, and the counter 38 converts each color density into the count number of the clock C4 and outputs it. A common potential V exceeding the threshold value is applied between the horizontal electrode 12 and the vertical electrode 130 of the liquid crystal panel 9 prior to image exposure. (an alternating voltage with continuous pulses shorter than the response time of the liquid crystal panel) is applied, and therefore each electrode facing portion 9a of the liquid crystal panel 9 is set to block light. The gate circuit 39 is operated at a timing synchronized with the rotation of the RGB filter 4, and while the number of clocks C4 corresponding to the respective color densities is being counted, the signal potential v0 is lowered to below the common potential Vot threshold; V2...Vo is applied to each vertical electrode 13. Therefore, the potential between both electrodes 12 and 13 of each electrode facing portion 9, 9a2, . The object becomes a light-transmitting state (bright area).

Here, as shown in FIG. 7, the time during which the clock C2 is counted, that is, the time during which the common potential Vo falls below the threshold value, can be controlled according to the image signal. Due to the difference in the count number of the clock C4, each electrode facing portion 9a1, 9a2...
... 9a (in other words, the amount of exposure light irradiated onto the photosensitive material 3), the photosensitive material 3 is exposed to an image with gradations.

As described above, exposure via the liquid crystal panel 9 is performed on the photosensitive material 3.
This is performed for each R1GXB signal in synchronization with the RGB filter 4 at the same position, and by moving the photosensitive material 3 as described above, the photosensitive material 3
A color two-dimensional image is exposed above. Second
As shown in Figure B, in the liquid crystal panel 9 that blocks light when voltage is applied, the opening response of the liquid crystal panel is relatively slow when voltage application is completely stopped, and the closing response is fast.
By finely controlling the count number of the clock C4, it is possible to obtain particularly rich gradations. To further clarify this point, FIG. 8 shows the relationship between the gradation signal and the opening degree of the liquid crystal panel for both the parallel Nicol type TN liquid crystal and the crossed Nicol type TN liquid crystal used in the above embodiment. The eighth
As clearly shown in the figure, when a parallel Nicol type TN liquid crystal is used, fine tone settings cannot be made in a low density region.

Further, as shown in FIG. 3, in the crossed Nicol type TN liquid crystal, the amount of leaked light is not affected by the wavelength of the light, and the amount of leaked light itself is small. It is possible to form a color image using the photosensitive material 3, and a material with a wide exposure range can be used as the photosensitive material 3.

Note that the liquid crystal drive circuit shown in FIG. 6 may be modified such that the counter 38 is removed from the liquid crystal driver 40 and installed on the circuit main body side, like the liquid crystal drive circuit shown in FIG. 9.

In this way, the liquid crystal driver 40 integrated with the liquid crystal panel 9 can be formed in a small size.

In this case, the count number of the clock C4 counted by the counter 38 is stored in the line memory 55.

Furthermore, as in the liquid crystal drive circuit shown in FIG.
B signal respective line memories 36R, 36G,
36B, and line memories 55R, 55G, and 55B for storing the count numbers of the clock C4 for each.
'eR.

The one with a total of three for GXB, that is, the electrode facing part is 9a11.9a1. ...9 aunt 9 a2+,
9a22...9atnz 9 a, 9a32,...
A panel with 3 rows of 9a3° is used, and the liquid crystal panel 60
A filter of RXGlB is fixedly installed corresponding to each array of , and a common potential V is set. The horizontal electrodes 12 to which the voltage is applied may be sequentially selected by the line selection circuit 61 so that each color exposure is performed each time the array passes through. This eliminates the need for a drive mechanism for the RGB filters and increases the efficiency of using exposure light.

Here, as mentioned above, since a color photosensitive material 3 that has a shortening characteristic is used, as shown in FIG. This effect does not appear as a density difference, and an image with good whiteness and blackness can be obtained. 11th
In the figure, the solid lines are the characteristics when using photosensitive materials such as ColorPaper ζ-, and the broken lines are the characteristics of Fuji Photo Film Co., Ltd.
This is the case with photosensitive materials such as Photorama (trade name).

It is well known among those skilled in the art that halogen silver photosensitive materials generally have the best halftone reproduction characteristics, but also have anti-fixation breakage characteristics.

When blackening with high-energy particles such as electron beams, it does not exhibit the shortening characteristic, but when blackening with light, development nuclei are not formed unless the number of photons exceeds a certain amount, and when the number of photons is below a certain amount, Photoelectrons become a loss. In other words, it becomes a short-circuit characteristic. In order to make this undercutting property a continuous property, different types of particles are usually mixed or the coating is applied in two layers. In the case of a combination with a liquid crystal, it is rather difficult to use a photosensitive material (1
~3rd place photosensitive materials) are a good match.

When a color photosensitive material 3 that requires normal development processing is used, the color photosensitive material 3 can be completely automatically supplied to the developing unit by the conveyor belt 8. Furthermore, a self-processing film unit, a so-called instant photographic film, can also be used as the color photosensitive material 3. In such a case, a normal developing unit is not provided, and the film is passed through a processing liquid development roll and immediately printed. can get.

Further, the image forming method of the above embodiment is applied to an array type liquid crystal panel 9.60, but the image forming method of the present invention uses a so-called matrix type liquid crystal panel facing the photosensitive material as the liquid crystal panel. However, it can also be applied when forming a two-dimensional image without moving the photosensitive material.

Furthermore, although the image forming method of the above embodiment is applied to a printer that obtains a color printer, the method of the present invention is applicable to an apparatus that does not have a means for forming a color image and forms a monochromatic gray image. Of course, it can also be applied.

(Effects of the Invention) According to the image forming method of the present invention as described above in detail, the gradation can be set particularly finely.

Because of this, you can get particularly smooth images with rich midtones,
In addition, since it is possible to use photosensitive materials with a wide exposure range, images with a wide dynamic range can be obtained.Furthermore, when forming a color image, there is no need to switch the LCD panel depending on the total exposure light, simplifying the equipment and operation. Become so.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a printer to which the first embodiment method of the present invention is applied. Second, FIG. 2B shows the response characteristics of the liquid crystal used in the conventional method and the liquid crystal used in the method of the present invention, respectively. Graph; FIG. 3 is a graph showing the relationship between the wavelength of light and the amount of leaked light in the liquid crystal used in the conventional method and the liquid crystal used in the method of the present invention; FIG. 4 is a side sectional view of the liquid crystal panel used in the printer; FIG. 5 is a plan view showing the transparent electrodes of the liquid crystal panel, FIG. 6 is a block diagram showing the liquid crystal drive circuit of the printer, FIG. 7 is an explanatory diagram explaining the operation of the liquid crystal in the printer, and FIG. A graph showing the open response characteristics of the liquid crystal in the present invention in comparison with the open response characteristics of other liquid crystals. Figures 9 and 10 each show a liquid crystal drive circuit used in another embodiment method of the present invention. Block Diagram FIG. 11 is a graph showing the characteristics of the photosensitive material used in the method of the first embodiment. 2... Line light source 3... Photosensitive material 9.60
...Liquid crystal panel 9a...Lion facing part ■Garasu 12・
...Horizontal electrode 13...Vertical electrode 17...Liquid crystal L...Exposure light No. 6
Figure 7, 95th G.J (-111111111111)
Shi-11111. C (903)
--- (Voluntary) Procedural Amendment Written by the Commissioner of the Japan Patent Office June 20, 1985 2. Name of the invention Image forming method 3. Relationship with the person making the amendment case Patent applicant address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name
Fuji Photo Film Co., Ltd. 4, Agent 7th floor, Uraiya Building, 5-2-1 Roppongi, Minato-ku, Tokyo (731g> Patent attorney Yanagi 1) Masashi (1 idiot) 5
, Date of amendment order None 6, Number of inventions increased by amendment None 7, Subject of amendment [Claims J and (1) of the description]
) The "Scope of Claims" has been amended as shown in the attached sheet. (2) 2 locations on page 3, line 4 of the specification, and line 12 on the same page)
Lines 12-13 of the same page, Line 13 of the same page, Line 14 of the same page, Last line of the page, Line 1 of page 4, Line 4 of the same page, Line 12 of the same page,
Line 16 of the same page, Line 19 of the same page, Line 1 of page 5, Line 3 of the same page
line, line 4 of the same page, line 5 of the same page, line 7 of the same page, line 10 of the same page
line, line 11 on the same page, line 2 on page 6, line 4 on the same page, line 9 on the same page (2 locations), line 11 on the same page, line 17 on the same page, line 4 on page 8, Line 5 of the same page, Lines 6-7 of the same page, Line 15 of the 9th page, Line 10 of the 10th page, Lines 18-19 of the same page, Line 2 of the same page, Line 14 of the same page, Page 12, line 3, page 7, line 17, page 13, line 19, page 14, line 6, page 14, line 7, page 12, line 13, Same page No. 1411
, same page line 16, same page line 19, page 15 line 1, same page line 9, same page line 19, page 16 line 3, page 18 line 6
line, line 7 of the same page, line 4 of page 19, line 16 of the same page, line 18 of the same page, line 4 of page 20, line 5 of the same page, line 14 of the page “Next to LCD J” Added "Shutter" to. (3) "Response" on page 4, line 14, page 6, line 13, and page 12, line 15, is corrected to "fall." (4) Delete "Panel" on page 12, line 15 of the specification, page 14, line 7, and line 14 of the same page. (5) Next to "Time" on page 12, line 15, [(After stopping the voltage application to the liquid crystal,
time until the response waveform reaches 10% of the steady state)] is added. (6), page 12, line 15, add ``period'' after ``short''. (7) Replace “18” on page 9, line 9 and page 10, line 7 with “18”.
Corrected to 19J. (8) On page 10, line 3, "21" is corrected to "22". (9) Replace Figures 2A, 2B, 8 and 11 with the attached figures. (10) Figure 7 is corrected as shown in the attached figure. Claim 1) A liquid crystal shutter array or matrix as a light valve is interposed between a photosensitive material and a light source, and light irradiated from the light source to the photosensitive material is applied to each pixel of the liquid crystal shutter array or matrix. In an image forming method that performs image-wise exposure by driving and controlling a liquid crystal, the liquid crystal shutter array or matrix is of a type that blocks light when a voltage is applied, and prior to the exposure, the liquid crystal is exposed to light from the fall time of the liquid crystal. A short pulse voltage is continuously applied to block the light, and then the voltage application to the liquid crystal is interrupted for a time corresponding to the image signal to limit the liquid crystal shutter to a light transmitting state. An image forming method characterized by using a photosensitive material whose tone can be visualized. 2) The image forming method according to claim 1, wherein a photosensitive material having a short-cut property is used as the photosensitive material.

Claims (1)

[Scope of Claims] 1) A liquid crystal array or matrix as a light valve is interposed between a photosensitive material and a light source, and light irradiated from the light source to the photosensitive material is applied to each pixel of the liquid crystal array or matrix. In an image forming method that performs image-wise exposure by driving and controlling a liquid crystal, the liquid crystal array or matrix is of a type that blocks light when voltage is applied, and prior to the exposure, the liquid crystal is exposed to light according to the response time of the liquid crystal. A short pulse voltage is continuously applied to block the light, and then the voltage application to each liquid crystal is interrupted for a time corresponding to the image signal to set the liquid crystal to a light transmitting state and to set an intermediate tone as the photosensitive material. An image forming method characterized by using a photosensitive material capable of expressing. 2) The image forming method according to claim 1, characterized in that the photosensitive material is a photosensitive material having a shorting property.