JPH11288047A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device capable of satisfactorily recording an image from a low density area to a high density area, irrespective of the adjustment of image data, that is, capable of accomplishing high-quality recording. SOLUTION: As for the image forming device, the device is provided with at least a light source system 10, an optical transmission system 12, an optical modulation system 14, an image forming optical system 17 and an optical filter 11, and the image is formed on a halftone recordable recording medium. In this case, the device is provided with a control mechanism for controlling so that light intensity at the image forming point on the recording medium may be kept constant in the case the optical modulation system 14 is made in a prescribed active state, and by keeping an image density level constant, a light quantity adjustment range by actual image data is largely secured so as to record the image with an appropriate tone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a color image on a recording medium by adjusting the amount of light by a light modulation element while a light source is constantly turned on.

[0002]

2. Description of the Related Art In order to record an image with light, there are a method of adjusting the light amount by switching a light source itself, and a method of adjusting the light amount by a light modulation element while the light source is constantly turned on. The former switchable light source method includes L
Although there are EDs, lasers, CRTs, fluorescent print heads, and the like, the light intensity in the off state is extremely small or almost zero compared to the on state.

On the other hand, the latter method is typically a liquid crystal shutter or a PLZT element, and is superior to the former method in that, when performing color recording, sequential recording can be performed only by changing color filters. Another advantage is that there is no need to prepare a light source that can be switched for each color (at least three colors of R, G, and B) as in the former method.

[0004]

However, there is a certain amount of light leakage even in the off state (the state in which light is blocked), and the light intensity ratio (extinction ratio) to the on state is about two to three digits. stay. Therefore, light quantity adjustment is necessary to perform recording from a sufficiently high density to a low density. That is, if the light quantity adjustment is insufficient, the fog phenomenon in the low density area or the insufficient maximum density is caused, and the image quality is significantly impaired. In this case, in the case of controlling by adjusting the image data, it is necessary to set such that the maximum density can be achieved with smaller image data in anticipation of a decrease in light amount, and the restrictions are severe.

An object of the present invention is to provide an image forming apparatus capable of high-quality recording capable of sufficiently recording from a low density range to a high density range without adjusting image data. It is an object.

[0006]

In order to achieve the above object, the present invention provides a recording medium which includes at least a light source system, a light transmission system, a light modulation system, an imaging optical system, and an optical filter, and is capable of halftone recording. An image forming apparatus for forming an image on
It is characterized by having a control mechanism such that the light intensity at the image forming point on the recording medium when the light modulation system is in a predetermined operation state is constant, and by maintaining the image density level constant, The configuration is such that a wide range of light quantity adjustment by data is ensured, and image recording at an appropriate gradation becomes possible.

According to a second aspect of the present invention, the control mechanism includes a means for detecting a light intensity at a predetermined position from the light source system, and a reference signal of the control mechanism is a reference light from the light source system. , So that it can be obtained relatively easily.

Further, the invention according to claim 3 is characterized in that the control mechanism includes means for detecting the light intensity at a position corresponding to the recording medium when the light modulation system is in a transmission state (on state). , So that the reference signal of the control mechanism can be obtained accurately.

Further, according to a fourth aspect of the present invention, the control mechanism drives the light modulation system in a predetermined steady state, wherein the density information from the image density detecting means for detecting the image density formed on the recording medium, Alternatively, it includes a control information output means which can be adjusted based on density information or the like separately obtained outside the apparatus, and controls under conditions formed on a recording medium through a light modulation system driven in a steady state. The mechanism is configured so that the reference signal of the mechanism can be obtained accurately. Further, the apparatus is configured such that density information measured outside the apparatus can be used instead of the reference signal.

Further, the invention according to claim 5 is characterized in that the control mechanism includes a control means for controlling a driving condition of a light source system, and keeps a light intensity at an image forming point on a recording medium. Such control is directly and easily performed.

Further, according to a sixth aspect of the present invention, in the case where the control mechanism performs the halftone recording based on the length of the on-state time according to the image data, the control mechanism controls the length of the on-time unit time. It is characterized by including a control means for controlling the image quality, so that the control in the case of performing the halftone recording can be performed at a high speed.

Further, the invention according to claim 7 is characterized in that the control mechanism includes a control means for controlling a transmittance condition of an ON state and an OFF state of a light modulation system, The control is performed so that the light intensity at the image point is kept constant.

Further, the invention according to claim 8 is characterized in that the control mechanism includes control means for controlling the transmission density of the optical filter inserted somewhere between the light source system and the recording medium. The control for making the light intensity at the image forming point constant can be easily performed.

Further, the invention according to claim 9 is characterized in that the light modulation system is an array device.
The light modulation system is simplified so that high-speed image formation can be performed without increasing the cost and the size of the apparatus.

[0015] Furthermore, the invention according to claim 10 provides:
The array-shaped device is a PLZT element, and is configured so that high-speed and stable image formation can be achieved.

[0016] Furthermore, the invention according to claim 11 provides:
The recording medium capable of halftone recording is made of silver halide color paper, so that high-quality images can be formed at a low running cost.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of an image printer to which the present invention is applied, and FIG. 2 is a perspective view schematically showing an essential part of the present invention in which an optical recording system is enlarged.

Image printer body 1 to which the present invention is applied
As shown in FIG. 1, image information captured by a scanner 5 is recorded by an optical recording system 6 on a recording medium (photographic paper) 4 which is a silver halide color photosensitive material pulled out from a photographic paper magazine 2 by a transport means 3. Then, the developing unit 7
, And is subjected to a developing process, cut into a predetermined size by a cutter 8 and discharged onto a discharge tray 9. Needless to say, the cutting may be performed before the sheet is conveyed to the developing unit 7.

As shown in FIG. 2, the optical recording system 6 transmits a light K which is transmitted from a light source system (white light source) 10 through a rotary color filter 11 to an input unit 13 of a light transmission system (optical fiber) 12. Through an optical fiber 12 to a light modulation system (PLZT array) 14 to expose the recording medium 4 at a predetermined position.

The exposure is performed on a recording medium 4 conveyed in the direction of the arrow by conveying rollers 3a and 3b rotating in connection with a driving source (not shown).
Exposure of the color filter 4 and the color filter 11 is controlled according to image data R, G, and B according to instructions from the image output control unit 15 and the filter switching control unit 16. When the exposure process is completed, the recording medium 4 is conveyed to the developing unit 7 as described above, and an output image is obtained through a predetermined developing process.

The PLZT array 14 employed as the light modulation system employs a plurality of PLZT shutter elements arranged at 300 dpi in a single line array, and a recording medium through a cell hoc lens array as an image forming optical system 17 thereof. 4, which is effective in increasing the recording speed.

Although the recording medium 4 has been described as being in the form of a roll, it may be cut paper from the beginning of paper feeding. The transport means 3 for the recording medium 4 is not limited to the transport rollers 3a and 3b shown in FIGS. further,
The recording medium 4 may be fixed and the print head may move, or the recording medium and the PLZT array may move together.

The imaging optical system 17 of the PLZT array 14
Although a roof mirror lens array or the like may be used, the use of a cell hoc lens array has an advantage that it can contribute to the realization of miniaturization and cost reduction of the entire apparatus.

Although the recording operation has been described as an example of an array in which the PLZT shutter elements are arranged in a line, recording on a recording medium is also possible in an array in which a plurality of recording elements are arranged or in a two-dimensional panel. By appropriately setting the timing with respect to the position and performing exposure control, a color image can be recorded.

Further, as another embodiment of the present invention, the same effect can be obtained even when performing image recording by combining a shutter array such as a liquid crystal shutter array.

In the present apparatus, the light K from the light source system 10 is
When the light is transmitted through the rotary color filter 11 to form an image on the recording medium 4 from the input unit 13 through the optical fiber 12 and the PLZT array 14, a control mechanism 18 for keeping the light intensity at the image forming point constant. Have. The control mechanism 18 includes data detection means 18a and control means 18b which operates according to the output of the detection means 18a.

The data detecting means 18a includes the light source system 10
The light intensity data A 'at the position A in the vicinity of is also detected, and the light intensity data B at the position B corresponding to the recording medium when the PLZT array 14, which is the light modulation system, is in the transmission state (ON state). The image density data C 'formed on the recording medium 4 when the PLZT array 14, which is a light modulation system, is driven in a predetermined steady state.
May be detected at the position C on the recording medium 4.

The control means 18b controls the light intensity at the image forming point on the recording medium 4 to be constant. For example, even if the driving condition a of the driving means 19 of the light source system 10 is controlled, the light modulation system PLZT
In the case where the array 14 performs recording in accordance with the length of the on-state time in accordance with image data, even if the unit controls the length information b of the on-state unit time, the on / off state of the PLZT array 14 which is a light modulation system is also controlled. The light source system 1 controls the transmittance condition c between the state and the off state.
0 to an optical filter 11 inserted somewhere in the recording medium
The transmission density d may be controlled.

In a typical silver halide color light-sensitive material as a recording medium for performing halftone recording, recording at a sufficiently high to low density generally requires at least 40: 1.
Light amount adjustment is required. In other words, if the light amount adjustment range is narrower than this range, a fog phenomenon or an insufficient maximum density occurs in a low density region, resulting in a remarkable obstacle to image quality.

In the case of an array device, it is necessary to correct variations in the amount of light even for the same image data due to variations in transmittance and switching characteristics of each element. In this case, a driving method is employed in which the maximum value of the image data (4096 gradations, 409
The condition for achieving the maximum density in 5) is not sufficient, and it is necessary to have driving conditions (in order to obtain the maximum density even with an element having a small amount of light) so that a sufficiently high density can be obtained with smaller data. Accordingly, the ratio between the effective maximum light amount and the minimum light amount due to the leak light tends to become smaller.

Further, each member in the light path, such as a light source system, a light transmission system, a light modulation system, an image forming optical system, and an optical filter, changes its characteristics in accordance with aging, environmental changes, and the like. The light intensity changes. Therefore, in order to keep the recording density level constant, some kind of feedback mechanism is required, and the simplest method is to adjust the entire image data, and this method does not need to add a new adjustment mechanism. . However, in a system using a light modulation system in which light leakage is present, the light amount adjustment range for performing image recording is originally narrow, so that there is little room for adjusting the overall level with image data.

Further, in order to increase the extinction ratio of the light modulation device, a method of stacking the devices can be considered, but the device arrangement is complicated and the costly PLZT element has a large cost disadvantage.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an image forming apparatus for recording an image on a silver halide color paper (recording medium) 4 using a PLZT array print head, a data detecting means (optical sensor) 18a is arranged at a position A near the light source system 10. Then, the image output was performed when the control unit 18b operating according to the sensor output controls the transmittance condition c between the ON state and the OFF state according to the image data. The gradation control based on the image data is 4096 gradations, and gradation recording is performed by adjusting the amount of light in which each PLZT shutter element is in a transmission state for a multiple of a unit time in proportion to the image data. In addition, PLZ
The pixel having the minimum light intensity is about 20% smaller than the average value due to the variation of the T shutter element.

As a result, it has been found that the light sensor reduces the light amount of the light source system by about 30% within the life of the light source, including changes over time and environmental changes. Usually 3
When the light source level is reduced by about 0%, the effective extinction ratio, which is an effective light amount adjustment range, is less than 30, but in this embodiment, 40 necessary for recording on silver halide color paper is secured ( The same applies to other controls).
In addition, although there is a certain degree of variation in the characteristic change of each element, the variation in the magnitude of the variation is small relative to the overall change in the light amount (however, the order of the light amount is changed).
Accordingly, it was found that the minimum density was 0.1 and the maximum density was 2.0 or more, and that image recording with an appropriate gradation was possible.

[0035]

As described above, the present invention relates to an image forming apparatus which includes at least a light source system, a light transmission system, a light modulation system, an image forming optical system, and an optical filter and forms an image on a recording medium capable of halftone recording. The apparatus is characterized in that it has a control mechanism for making the light intensity at the image forming point on the recording medium constant when the light modulation system is in a predetermined operation state, so that the image density level is kept constant. In addition, since the light amount adjustment range based on the substantial image data can be secured widely, an excellent effect that the image can be recorded at an appropriate gradation can be obtained.

Further, the invention according to claim 2 is characterized in that the control mechanism includes means for detecting the light intensity at a predetermined position from the light source system, so that the reference signal of the control mechanism is radiated from the light source system. This has the effect that the light can be obtained relatively easily.

Further, the invention according to claim 3 is characterized in that the control mechanism includes means for detecting the light intensity at a position corresponding to the recording medium when the light modulation system is in a transmission state (on state). Therefore, an effect is obtained that a reference signal of the control mechanism can be obtained accurately.

Further, the invention according to a fourth aspect is characterized in that the control mechanism drives the light modulation system in a predetermined steady state, the density information from the image density detection means formed on the recording medium, Alternatively, it includes a control information output means that can be adjusted based on density information or the like separately obtained outside the apparatus, so that the condition formed on the recording medium through an optical modulation system driven in a steady state In this case, the reference signal of the control mechanism can be obtained accurately, or density information measured outside the apparatus can be used instead of the reference signal.

Further, the invention according to claim 5 is characterized in that the control mechanism includes control means for controlling the driving conditions of the light source system, so that the light intensity at the image forming point on the recording medium is kept constant. This is an effect that the control described above can be directly and easily performed.

According to a sixth aspect of the present invention, in the case where the control mechanism performs halftone recording based on the length of time in which the light modulation system is in the on state according to the image data, the unit time of the on state is increased. Since it is characterized by including a control means for controlling the light intensity, it has an effect that control for keeping the light intensity constant when performing halftone recording can be performed at a high speed.

Further, the invention according to claim 7 is characterized in that the control mechanism includes a control means for controlling a transmittance condition of an ON state and an OFF state of the light modulation system, so that a recording medium is provided. This has an effect that control for keeping the light intensity at the above image formation point constant can be performed accurately.

Further, the invention according to claim 8 is characterized in that the control mechanism includes control means for controlling the transmission density of the optical filter inserted somewhere between the light source system and the recording medium. This provides an effect that control for keeping the light intensity at the image forming point on the medium constant can be simplified.

Further, the invention according to claim 9 is characterized in that the light modulation system is an array-shaped device, so that the light modulation system can be simplified, leading to an increase in cost and an increase in the size of the apparatus. In other words, the effect of high-speed image formation can be obtained.

Further, the invention according to claim 10 is as follows:
Since the array-shaped device is a PLZT element, an effect of achieving high-speed and stable image formation can be achieved.

Further, the invention according to claim 11 is as follows:
Since the recording medium capable of halftone recording is made of silver halide color paper, high quality images can be formed at low running cost.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image printer to which the present invention is applied.

FIG. 2 is a schematic perspective view showing an essential part of the present invention in which an optical recording system is enlarged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image printer main body 2 Printing paper magazine 3 Conveying means 3a, 3b, drive roller 4 Recording medium (silver halide color photosensitive material) 5 Scanner 6 Recording head 7 Development processing part 8 Cutter 9 Discharge tray 10 Light source system (white light source) Reference Signs List 11 color filter 12 light transmission system (optical fiber) 13 input section of optical fiber 14 light modulation system (PLZT shutter array) 15 image output control section 16 filter switching control section 17 imaging optical system (cell hook lens array) 18 control mechanism 18a data Detecting means 18b Control means 19 Driving means A Position near light source system A 'Same as above, light intensity data obtained at position B Equivalent position of recording medium B' Same, light intensity data obtained at position C Position on recording medium C 'same , Image density data obtained at a position a driving condition b unit time length information c transmittance condition d Transmission density

Claims (11)

[Claims] 1. An image forming apparatus comprising at least a light source system, a light transmission system, a light modulation system, an image forming optical system, and an optical filter, and forming an image on a recording medium capable of halftone recording.
An image forming apparatus, comprising: a control mechanism for maintaining a constant light intensity at an image forming point on a recording medium when a light modulation system is set to a predetermined operation state. 2. The image forming apparatus according to claim 1, wherein the control mechanism includes a unit that detects a light intensity at a predetermined position from the light source. 3. The image according to claim 1, wherein the control mechanism includes a light intensity detecting unit at a position corresponding to a recording medium when the light modulation system is in a transmission state (on state). Forming equipment. 4. The density information from a means for detecting an image density formed on a recording medium when the control mechanism drives the light modulation system in a predetermined steady state, or density information separately obtained outside the apparatus. 2. The image forming apparatus according to claim 1, further comprising control information output means that can be adjusted on the basis of the control information. 5. The image forming apparatus according to claim 1, wherein said control mechanism includes control means for controlling a driving condition of a light source system. 6. The control mechanism includes control means for controlling the length of a unit time of the ON state when the optical modulation system performs halftone recording according to the length of the time of the ON state according to image data. The image forming apparatus according to any one of claims 1 to 4, wherein: 7. The image forming apparatus according to claim 1, wherein the control mechanism includes a control unit that controls a transmittance condition of an ON state and an OFF state of the light modulation system. . 8. The method according to claim 1, wherein the control mechanism includes a control unit for controlling a transmission density of the optical filter inserted somewhere between the light source system and the recording medium.
An image forming apparatus according to claim 1. 9. The image forming apparatus according to claim 1, wherein the light modulation system is an array device. 10. The image forming apparatus according to claim 9, wherein the array device is a PLZT element. 11. The image forming apparatus according to claim 1, wherein the recording medium capable of halftone recording is made of silver halide color paper.