JPH091839A - Optical fixing unit for color thermal printer - Google Patents

Abstract

PURPOSE: To prevent an excessive fixing or insufficient fixing from occurring due to the irregularity of the illuminance of an ultraviolet lamp if the lamp has the irregularity. CONSTITUTION: Two ultraviolet lamps 32a are aligned in a reflector 40 to constitute an optical fixing unit 32. A shutter plate 52 is provided between the unit 32 and a color thermal recording material 12. The plate 52 is closed by a shutter plate driver 61 immediately after feeding of the end of the material 12 is stopped by disposing the end of the material 12 at conveying roller pair 20 at the time of optically fixing. The closing speed of the plate 52 is decided to match the lamp 32a having low illuminance of the lamps 32a. The driving voltage of the lamp 32a having high illuminance is lowered to beam attenuate it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating type photo-fixing device for a color thermal printer, and more particularly to a photo-fixing device for a color thermal printer which carries out photo-fixing near the end of a color thermosensitive recording material. is there.

[0002]

2. Description of the Related Art At least three types of thermosensitive coloring layers such as a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and
A color thermal printer is known which prints a full-color image by using a color thermal recording material in which a yellow thermosensitive coloring layer is layered in order. In this color thermal printer,
At the time of printing, the thermal head is pressed against the color thermosensitive recording material, a yellow image is thermally recorded line by line on the yellow thermosensitive coloring layer having the highest thermal sensitivity, and immediately after that, the yellow thermosensitive coloring layer is optically fixed. Next, a magenta image is heat-recorded on the magenta thermosensitive coloring layer, and this is optically fixed. Finally, a cyan image is thermally recorded on the cyan thermosensitive coloring layer to obtain a full-color image.

Such thermal recording and optical fixing are performed while the color thermal recording material is relatively moved with respect to the thermal head and the optical fixing device. With this moving system, the color thermal printer is mainly used in the platen drum system. And reciprocating method. In the platen drum system, the color thermosensitive recording material is wound around a platen drum having a peripheral length corresponding to the length of the color thermosensitive recording material and rotated, and the color thermosensitive recording material is fixed to the platen drum. The tip of the color thermosensitive recording material is clamped by a clamper. This system requires a platen drum having a peripheral length corresponding to the length of the recording material in order to wind the color thermosensitive recording material. Therefore, the platen drum method is suitable for printing about the size of a postcard, and B5, A
In the case of printing in 4 sizes or the like, a platen drum having a large diameter is required to accommodate this, and it becomes difficult to downsize the apparatus. On the other hand, the color thermosensitive recording material is only slightly clamped at the tip, so that the recording surface can be effectively used in this platen drum system.

On the other hand, as shown in FIG. 10, in the reciprocating type color thermal printer, the leading end of the color thermal recording material 3 is nipped by a conveying roller pair 2 composed of an upper pressing roller 2a and a lower driving roller 2b. (In addition to gripping), while carrying in the forward direction of carrying from the paper feed tray 4 side to the paper discharge path 5 side and the reverse direction of carrying from the paper discharge path 5 side to the paper feed tray 4 side alternately, The color thermosensitive recording material 3 is sandwiched between the platen roller 7 and the thermal head 8 to thermally record three colors of yellow, magenta and cyan sequentially.

An optical fixing device 9 including a yellow ultraviolet lamp 9a and a magenta ultraviolet lamp 9b, and a reflector 9c that covers these lamps 9a and 9b is arranged downstream of the conveying roller pair 2 in the forward direction. The thermal recording is performed on each thermosensitive color developing layer while being transported in the forward direction, and the ultraviolet lamps 9a and 9b of the optical fixing device 9 are selectively turned on to transport the light in the forward direction or the reverse direction. Is supposed to do. In this system, it is not necessary to use a platen drum having a peripheral length corresponding to the length of the heat-sensitive recording material 3, and a platen roller 7 having a small diameter can be used, which is advantageous for downsizing of the apparatus. However, in such a reciprocating color thermal printer, the thermal recording material 3 is always sandwiched between the transport roller pair 2 in the transport system having a simple structure in order to prevent the displacement of the three color pixels. There is a need. Therefore, a sandwiching margin L1 sandwiched between the pair of conveying rollers 2 is required, and since this portion does not reach the optical fixing device, it cannot be fixed and becomes a blank portion.

Further, it is necessary to arrange the two kinds of ultraviolet lamps 9a and 9b side by side, which causes the area of insufficient fixing to be widened in the lamp 9b on the side away from the conveying roller pair 2.
Further, when the end portion of the recording material 3 is positioned on the conveying roller pair 2 and the feeding of the recording material 3 is stopped, the irradiation light amount accumulated in the portion that has reached the ultraviolet irradiation area first and the portion that has reached the ultraviolet irradiation area later. However, there is unevenness in the amount of optical fixing in this area.

Therefore, in the reciprocating type color thermal printer, the image quality is degraded due to unevenness in the optical fixing at the L2 portion. If you want uniform quality on the print screen,
It is necessary to make the above-mentioned L1 and the margin portion L3. As described above, the reciprocating method requires a large margin portion L3, which causes a problem that a printable portion becomes small.
In particular, when the fixing light amount is increased by using a plurality of lamps and the conveyance speed during fixing is increased to shorten the printing time, the ultraviolet irradiation area is further expanded, and thus this blank area is increased. There is a problem of becoming.

In order to reduce this blank area, FIG.
As shown in (A), two ultraviolet lamps 10a, 10
A shutter plate 11 is provided between the color thermosensitive recording material 12b and the color thermosensitive recording material 12b, and is closed so as to shield the electromagnetic rays from the ultraviolet lamps 10a and 10b by moving in the direction opposite to the feeding direction of the color thermosensitive recording material 12 during optical fixing. Is being considered.
In this case, immediately after the end of the color thermosensitive recording material 12 is positioned on the conveying roller pair 2 and the feeding is stopped at the time of optical fixing, the shutter plate is moved at the same speed as the feeding speed of the color thermosensitive recording material 12 before the stop. Make sure to close 11. As a result, even if the end of the recording material 12 reaches the optical fixing area, the fixing unevenness in this portion is eliminated, and it is possible to secure a large recording area by reducing the margin portion.

[0009]

[Problems to be Solved by the Invention]
As shown in (A), in the optical fixing device 10 including the ultraviolet lamps 10a and 10b and the reflector 10c, the uniform illuminance distribution as shown in (B) is ideal, but actually as shown in (F). It has a uniform illuminance distribution. Also,
In the case of the ideal illuminance distribution as shown in (B), the fixing light amount distribution immediately after the feeding of the color thermosensitive recording material 12 is stopped is as shown in (C). Then, in order to reduce the blank area at the rear end of the color thermosensitive recording material 12, the shutter plate 11 is provided on the same side as the side opposite to the feeding direction of the color thermosensitive recording material 12 immediately after the feeding of the color thermosensitive recording material 12 is stopped. When the shutter plate 11 is closed at high speed, the fixing light amount distribution during the closing operation of the shutter plate 11 is as shown in (D). Therefore, the integrated fixing light amount in such an ideal illuminance distribution is the sum of (C) and (D), and becomes uniform as shown in (E).

However, in reality, the optical fixing device 10 has an illuminance distribution as shown in (F). Moreover, the illuminance also varies between the individual ultraviolet lamps 10a and 10b, and the illuminance of either one is higher than that of the other. Therefore, for example, when the illuminance of the ultraviolet lamp 10a closer to the shutter plate side is low as shown in (F), as shown in FIG. When the closing speed is set, the overfixed portion COA1 is generated on the lamp side having higher illuminance than that in the ideal state shown by the two-dot chain line. When over-fixed, for example, a UV lamp 1 for fixing yellow light
The magenta thermosensitive recording layer to be thermally recorded next is also partially fixed due to the influence of the magenta light fixing ultraviolet rays contained in the irradiation light amounts of 0a and 10b. As a result, magenta coloring is insufficient at this overfixed portion, resulting in uneven color. On the contrary, as shown in (H), when the shutter plate closing speed is set to match the lamp 10b on the higher illuminance side, the fixing light amount insufficient portion on the lamp side of lower illuminance is lower than that of the ideal state shown by the two-dot chain line. CUA1 occurs. In this case, in the next magenta recording, the yellow thermosensitive coloring layer in the insufficiently fixed portion develops color, which causes color unevenness as well.

The present invention is to solve the above problems and provides an optical fixing device for a color thermal printer, which eliminates the unevenness of the integrated fixing light amount due to the illuminance variation when a plurality of fixing lamps are used. The purpose is to

[0012]

In order to achieve the above object, an optical fixing device for a color thermal printer according to claim 1 is provided with a plurality of fixing lamps arranged in the feeding direction of a color thermal recording material, and these fixing lamps. A reflector that reflects the electromagnetic radiation from the lamp to the color thermosensitive recording material side, and a reflector that is formed longer than the optical fixing area by this reflector, and feeds the color thermosensitive recording material during photofixing between the color thermosensitive recording material and the reflector. The shutter plate, which is movable in any direction, and the color plate during photo-fixing, which blocks electromagnetic radiation from the fixing lamp and reflector, immediately after the feeding of the color thermosensitive recording material is stopped near the end of photo-fixing. A shutter plate drive unit that moves in the direction opposite to the recording material feeding direction and closes is provided. When the leading end of the data sheet passes, and dim the UV lamp only high illuminance minute, it is obtained by substantially equalizing the accumulated fixing light quantity distribution.

Further, in the optical fixing device for a color thermal printer according to a second aspect of the present invention, a fixing light amount correction opening for irradiating the shutter plate with an electromagnetic ray from a fixing lamp in a portion where the fixing light amount is insufficient immediately before the closing of the shutter plate is completed. Is provided. Further, in the optical fixing device for a color thermal printer according to the third aspect of the present invention, the illuminance of the fixing lamp is increased near the completion of closing the shutter plate to make the integrated fixing light amount distribution substantially uniform.
Further, in the optical fixing device for the color thermal printer according to the fourth aspect, the closing speed of the shutter plate is reduced immediately after the closing of the shutter plate is completed, and the integrated fixing light amount distribution is made substantially uniform. Further, in the optical fixing device for a color thermal printer according to claim 5, a light receiving sensor is provided at the front end portion of the shutter plate, and the illuminance control section makes the integrated fixing light amount distribution uniform in the reflector based on a signal from the light receiving sensor. The illuminance of each ultraviolet lamp is controlled so that

[0014]

When the end of the color thermosensitive recording material is positioned at, for example, the pair of conveying rollers at the time of optical fixing and the feeding is stopped, the shutter plate is closed at a speed substantially equal to the feeding speed before the color thermosensitive recording material is stopped. To be As a result, even if the edge of the recording material reaches the optical fixing area, there is no fixing unevenness in this area, and the blank area is reduced. Therefore, a wide recording area can be secured.

Among the plurality of ultraviolet lamps, when the tip of the shutter plate passes through the irradiation area of the ultraviolet lamp having high illuminance, the ultraviolet lamp is dimmed by the amount corresponding to the high illuminance.
As a result, the occurrence of over-fixing due to high illuminance is eliminated, and the integrated fixing light amount distribution in the reflector after the feeding of the color thermosensitive recording material is stopped is made substantially uniform.
Further, immediately before the shutter plate is completely closed, the fixing light amount correction opening additionally irradiates an electromagnetic ray from the ultraviolet lamp to the portion where the fixing light amount is insufficient, so that the integrated fixing light amount distribution is further homogenized. Further, by increasing the illuminance of the fixing lamp near the completion of closing the shutter plate or by lowering the closing speed of the shutter plate near the completion of closing the shutter plate, the integrated fixing light amount distribution in the fixing area becomes more uniform. To be done.

In another invention, a light receiving sensor is arranged at the tip of the shutter plate and the shutter plate is closed to measure the actual illuminance distribution in the fixing area. Based on this illuminance distribution, the drive voltage of the ultraviolet lamp at the entry position of the shutter plate is obtained in order to make the integrated fixing light amount distribution in the fixing area uniform. Then, each ultraviolet lamp is driven by this drive voltage in synchronization with the closing operation of the shutter plate, so that the integrated fixing light amount distribution in the fixing area becomes uniform.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 2 showing an outline of a color thermal printer, a color thermal recording material 12 sent from a paper feeding tray 14 by a paper feeding roller 13 passes through a paper feeding passage 15 toward a first conveying roller 16. Be transported. The first conveying roller pair 16 includes a driving roller 16a and a pressing roller 16b.
The color heat-sensitive recording material 12 is nipped, and this is applied to the platen roller 17 and the thermal head 1.
Send between 8 and.

When the color thermosensitive recording material 12 passes between the platen roller 17 and the thermal head 18, it is conveyed toward the second conveying roller pair 20. The second conveying roller pair 20 is also composed of a driving roller 20a and a pressing roller 20b, and the color thermosensitive recording material 1 is provided between them.
2 is nipped and conveyed.

As is well known, a large number of heating elements 18a are arranged in a line on the thermal head 18. The thermal head 18 is swingable by a mounting shaft 18b. Further, a pressing mechanism 21 is linked to the thermal head 18, and the pressing mechanism 21 presses the heating element 18a against the color thermosensitive recording material 12 and a retracted position away from the color thermosensitive recording material 12 (in the figure). (Indicated by a two-dot chain line), the thermal head 18 is displaced. Also,
Each heating element 18a is controlled by the print controller 22. The print controller 22 stores image data for each color in a built-in frame memory, and heats each heating element 18a according to the color to be recorded and the density of the pixel based on this image data, and the color thermosensitive recording material 1 is printed.
2 is developed at a desired density and printing is performed.

As shown in FIG. 3, the color thermosensitive recording material 1
In No. 2, a cyan thermosensitive coloring layer 26, a magenta thermosensitive coloring layer 27, a yellow thermosensitive coloring layer 28, and a protective layer 29 are sequentially laminated on a support 25. Each of these thermosensitive coloring layers 26
Nos. To 28 are layered from the surface in the order of thermal recording. For example, when recording in the order of magenta, yellow, and cyan, the positions of the yellow thermosensitive coloring layer 28 and the magenta thermosensitive coloring layer 27 are interchanged. To be An opaque coated paper or a plastic film is used as the support 25, and a transparent plastic film is used when an OHP sheet is produced.

The cyan thermosensitive coloring layer 26 contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops cyan when heated. Magenta thermosensitive coloring layer 2
No. 7 contains a diazonium salt compound having a maximum absorption wavelength of about 365 nm, and a coupler which thermally reacts with this compound to develop magenta color. When the magenta thermosensitive coloring layer 27 is irradiated with ultraviolet light near 365 nm after thermal recording, the diazonium salt compound is photolyzed and loses its coloring ability. The yellow thermosensitive coloring layer 28 has a maximum absorption wavelength of about 42
It contains a diazonium salt compound having a thickness of 0 nm and a coupler which reacts with the diazonium salt compound to develop a yellow color. When the yellow thermosensitive coloring layer 28 is irradiated with ultraviolet rays in the vicinity of 420 nm, the yellow thermosensitive coloring layer 28 is optically fixed and loses its coloring ability.

As shown in FIG. 2, the second conveying roller pair 20
A guide plate 30 and a photo-fixing device 31 are arranged on the downstream side of the forward feed (feed to the right in the figure). The optical fixing device 31 includes first and second optical fixing devices 32 and 33, a rotating frame 34, a swinging frame 35, and an interlocking mechanism 36 that interlocks these.

The first optical fixing device 32 is composed of two yellow ultraviolet lamps 32a and 32b and a reflector 40. The reflector 40 is an ultraviolet lamp 32.
The color thermosensitive recording material 12 is irradiated with the ultraviolet rays emitted from a and 32b. Similarly, the second optical fixing device 33 also includes magenta ultraviolet lamps 33a and 33b and a reflector 41. UV lamp 3 for yellow
2a and 32b radiate ultraviolet rays having an emission peak of about 420 nm to optically fix the yellow thermosensitive coloring layer 28, and magenta ultraviolet lamps 33a and 33b emit ultraviolet rays having an emission peak of about 365 nm to generate magenta thermosensitive coloring layer 27.
Perform optical fixing.

The optical fixing devices 32 and 33 are attached to a rotating frame 34, and are alternately set at a fixing position by rotating the rotating frame 34 by 105 degrees. The rotating frame 34 is rotatably attached to the swing frame 35 via a mounting shaft 42. The swing frame 35 is swingably attached to the stay 43 via a swing shaft 44. The swing frame 35 and the rotating frame 34 are linked by an interlocking mechanism 36.

The interlocking mechanism 36 is composed of a motor, a gear train, a cam, etc., which are not shown. The swing frame 35 is swung within a range of 10 degrees about the swing shaft 44 so that the swing frame 35 can be seen. 2 is moved between the fixing position shown by the solid line and the retracted position shown by the chain double-dashed line. Furthermore, the interlocking mechanism 36
Interlocking with this swing, when the swing frame 35 is in the retracted position, the swing frame 34 is swung within a range of 105 degrees, and either one of the optical fixing devices 32 and 33 is moved to the optical fixing position. set.

FIG. 4 is a view for explaining the movement of the interlocking mechanism 36. From the yellow light fixing state of FIG.
As shown in (B), the swing frame 35 is moved counterclockwise by 1
Rotate 0 degrees, and then turn the rotating frame 34 as shown in (C).
Rotates 105 degrees in the clockwise direction, and then the swing frame 35 rotates 10 degrees in the clockwise direction to return to the original position as shown in (D), whereby the magenta light fixing state is established. Also,
To return from the magenta light fixing state to the yellow light fixing state, the rotation or swinging operation of each frame 34, 35 is performed as shown in FIGS. 4 (D), (C), (B) and (A). The interlocking between the swing of the swing frame 35 and the swing of the swing frame 34 is changed to mechanical control using a cam or a link.
It may be performed by electrical control using an electromagnetic clutch brake or the like.

As shown in FIG. 2, the rotating frame 34 is
It is bent into a V shape at an angle of 5 degrees and is attached to the attachment shaft 42 by a frame attachment bracket 46. The frame mounting bracket 46 is used for the rotating frame 34.
The mounting shaft 42 is positioned on the center line of the line symmetry. The rotating frame 34 has a reflector 40,
41 and a lamp mounting bracket 47 are attached. As is well known, the lamp mounting bracket 47 holds the contact pins of the bases of the ultraviolet lamps 32a, 32b, 33a, 33b with built-in contact pieces, so that the ultraviolet lamps 32a, 32b, 3 inside the reflectors 40, 41.
3a and 33b are arranged. A lamp cover 48 is attached to the rotating frame 34 near both ends of the reflectors 40 and 41, and the lamp cover 48 covers near both ends of the ultraviolet lamps 32a, 32b, 33a and 33b. Below the guide plate 30, the ultraviolet lamps 32a and 32b located outside the recording area and at the optical fixing position are provided.
Alternatively, the light receiving sensors 50a and 50b are provided below 33a and 33b.
Is arranged.

The light receiving sensors 50a and 50b are composed of well-known phototransistors and photoelectrically convert the irradiation light from the ultraviolet lamps 32a and 32b or 33a and 33b at the fixing position. As shown in FIG. 2, this photoelectric signal is sent to the illuminance measuring circuit 57. The illuminance measuring circuit 57 obtains an illuminance signal based on the photoelectric signal, and uses this to obtain the illuminance signal from the controller 5
Send to 8. The controller 58 uses the color thermosensitive recording material 1
At the time of performing the optical fixing while sending 2, the ultraviolet lamps 32a, 32b or 33 at the fixing position based on the illuminance signal.
Each UV lamp 3 so that the illuminance of a and 33b is constant
The drive voltages of 2a, 32b, 33a and 33b are obtained and sent to the voltage control circuit 59. Based on this drive voltage, the voltage control circuit 59 causes the ultraviolet lamps 32a, 32b, 33 to
a and 33b are driven. The illuminance measuring circuit 57, the controller 58, and the voltage control lighting circuit 59 constitute an illuminance control section.

A shutter plate 52 for blocking the ultraviolet rays from the optical fixing device 32 is provided at the optical fixing position.
The shutter plate 52 is arranged so as to be parallel to the color thermosensitive recording material 12, and is reciprocated by the shutter plate driving section 61 in parallel to the feeding direction of the color thermosensitive recording material 12. As a result, the shutter plate 52 moves between the closed position that enters the optical fixing position as shown by the chain double-dashed line and shields the optical fixing device 32 from the open position that is retracted from the optical fixing position as shown by the solid line. .

As shown in FIG. 1A, the shutter plate drive section 61 includes a rack 63 attached to the shutter plate 52,
The pinion 64 meshes with the pinion 64 and the pulse motor 65 that rotates the pinion 64. The rotation of the pulse motor 65 is controlled by the controller 58 via the driver 66. The shutter plate drive unit 61 may be any device that can convert the rotational motion of the motor 65 into the reciprocating motion of the shutter plate 52, and is configured by a slider crank mechanism, a link mechanism, or the like, instead of the rack and pinion mechanism. You may.

As shown in FIG. 1C, the shutter plate 52
Is short in the width direction so as to cover the entire color thermosensitive recording material 12 and not block the optical paths of the light receiving sensors 50a and 50b. Therefore, the shutter plate 5
Each UV lamp 3 even when 2 is set to the closed position
The illuminance of 2a and 32b can be measured.

The illuminance control section uses two ultraviolet lamps 3 when the color thermosensitive recording material 12 is optically fixed while being sent.
Both 2a and 32b are turned on, and these ultraviolet lamps 3
The illuminance is kept constant by controlling the drive voltages of 2a and 32b. When the rear end of the color thermosensitive recording material 12 is optically fixed by moving the shutter plate 52 after the feeding of the color thermosensitive recording material 12 is stopped, the closing operation of the shutter plate 52 will be described in detail later. In conjunction with the above, the ultraviolet lamp having a high illuminance, for example, 32b is temporarily dimmed to eliminate the occurrence of over-fixing due to the high illuminance.

The controller 58 is composed of a well-known microcomputer, and counts the number of motor drive pulses of a conveyance pulse motor (not shown) for feeding the color thermosensitive recording material 12 so as to count. Is tracked, and each part is sequence-controlled based on this tracking signal. Further, the controller 58 uniformizes the integrated fixing light amount distribution in the fixing area LA, which is generated due to the unevenness of the illuminance of the ultraviolet lamps 32a and 32b, during the closing operation of the shutter plate 52. Each ultraviolet lamp 32a, 3 according to
2b is selectively dimmed. Therefore, each UV lamp 3
The illuminances La and Lb of 2a and 32b are measured, the lamp to be dimmed is specified, and the driving voltage for dimming is set.

This illuminance measurement adjustment mode is selected and executed when the adjustment process after the assembly is completed or when the ultraviolet lamps 32a and 32b are replaced. The processing procedure in this illuminance measurement adjustment mode is shown in FIG. In this illuminance measurement adjustment mode, as shown in FIG.
The illuminance of the first ultraviolet lamp 32a and the second ultraviolet lamp 32b is measured by the illuminance measuring circuit 57 using the two light receiving sensors 50a and 50b. Instead of using the two light receiving sensors 50a and 50b, one light receiving sensor is provided at a position where the irradiation light is equally received from the two ultraviolet lamps 32a and 32b, and the light receiving sensor is used to measure the object. Only the lamp may be turned on and the illuminance of this may be measured alternately.

As shown in FIG. 5, measured illuminances La and Lb
Are compared by the controller 58. Then, the shutter plate 5 is adjusted according to the illuminance of the ultraviolet lamp on the low illuminance side.
The closing speed Vsa or Vsb of 2 is determined. Also,
The absolute value of the illuminance difference La-Lb is calculated, and the dimming drive voltage DV of the ultraviolet lamp on the high illuminance side is obtained according to this value. The dimming target lamp has a higher illuminance. For example, when the illuminance of the first ultraviolet lamp 32a is high, the first ultraviolet lamp 32a is the target, and conversely, when the illuminance of the second ultraviolet lamp 32b is high, the second ultraviolet light is emitted. Lamp 32
b is the target. Further, the dimming drive voltage DV is equal to the illuminance difference La.
When the absolute value of −Lb is small, the value is increased, and when the absolute value is large, the value is decreased. The UV lamp to be dimmed may be constantly dimmed during lighting. In this case, since the integrated fixing light amount corresponding to the maximum illuminance portion can be reduced, the integrated fixing light amount distribution can be made more uniform. The measured illuminances La and Lb are almost the same,
When the absolute value of the difference between the measured illuminances La and Lb is smaller than the constant value k, it is not necessary to adjust the illuminance variation, so the closing speed of the shutter plate 52 is set to the color thermosensitive recording material 1.
Set the same as the feed rate of 2 and exit this mode.

The relationship between the absolute value of the difference between the measured illuminances La and Lb of the ultraviolet lamps 32a and 32b and the dimming drive voltage DV for dimming the ultraviolet lamps on the high illuminance side is optimally determined in advance by experiments or the like. It is sought to obtain a specific integrated fixing light amount, which is stored in the memory in a look-up table format. Further, the relationship between the illuminance of the ultraviolet lamp having low illuminance and the closing speed of the shutter plate 52 is also obtained in advance by experiments or the like so as to obtain the optimum integrated fixing light amount, and is similarly stored in a memory in a look-up table format. Has been done.

Next, the operation of the above embodiment will be described.
First, when the print start switch is operated, as shown in FIG. The sheet is conveyed toward the pair of conveying rollers 16. When the leading end of the color thermosensitive recording material 12 is nipped by the first conveying roller pair 16, the paper feeding roller 13 is in a free state and the feeding of the color thermosensitive recording material 12 is stopped.

The color thermosensitive recording material 12 that has passed between the platen roller 17 and the thermal head 18 by the first conveying roller pair 16 is nipped and conveyed by the second conveying roller pair 20. After the nip, when the heating element 18a of the thermal head 18 is located at the head pressing start position of the color thermosensitive recording material 12, the pressing mechanism 21 rotates the thermal head 18 in the clockwise direction to move the heating element 18a to the color thermosensitive recording material. Press 12

In this state, the color thermosensitive recording material 12 is conveyed in the forward direction by the first and second conveying roller pairs 16 and 20, and the tip of the recording area of the color thermosensitive recording material 12 is moved to each heating element 18a during the conveyance. When the temperature reaches, the heat generating elements 18a generate heat energy corresponding to the pixels to thermally record the yellow image on the yellow thermosensitive coloring layer 28 line by line. When recording one pixel, each heating element 18a supplies bias thermal energy for bringing the yellow thermosensitive coloring layer 28 into a state before coloring, and gradation expression thermal energy corresponding to the coloring density, in the color thermosensitive recording material 12. Give to. Further, the yellow ultraviolet lamp 32 is synchronized with the yellow thermal recording.
a and 32b are turned on. This yellow UV lamp 3
Near-ultraviolet rays in the vicinity of 420 nm are applied to the color thermosensitive recording material 12 by 2a and 32b, and the magenta thermosensitive coloring layer 27 is fixed so that yellow does not develop during the next thermal recording.

When the yellow image is thermally recorded up to the rear end of the recording area of the color thermosensitive recording material 12, the thermal head 18 is set at the retracted position away from the color thermosensitive recording material 12, and the first and second conveyances are performed. Roller pair 16, 20
Is temporarily stopped, and the feeding of the color thermosensitive recording material 12 is stopped. Immediately after this, the shutter plate drive unit 61 operates to close the shutter plate 52. As shown in FIG. 5, the moving speed of the shutter plate 52 is determined according to the illuminance of the ultraviolet lamp of low illuminance, and the color thermosensitive recording material 12
Color light-sensitive recording material 1
The cumulative fixing light amount due to the closing operation of the shutter plate after stopping the feeding of 2 is made substantially the same. Also,
According to the variation in the illuminance of each of the ultraviolet lamps 32a and 32b, the driving voltage of the lamp having the higher illuminance is lowered and dimmed in accordance with the higher the illuminance.

FIG. 1B is a diagram showing a state in which the integrated fixing light amount is corrected by lowering the drive voltage DV of the lamp 32b having high illuminance, and is indicated by a correction area CA1 by dimming the lamp 32b. As described above, since this portion is reduced, a substantially uniform integrated fixing light amount distribution can be obtained. As a result, the unevenness of the integrated fixing light amount due to the illuminance variation is reduced.

When the shutter plate 52 completely covers the reflector 40, the ultraviolet lamps 32a and 32b at the fixing position are turned off. After that, the shutter plate 52 is returned to the original position by the shutter plate drive unit 61. Further, as shown in FIG. 2, the first and second conveying roller pairs 16 and 20 rotate in the opposite directions to convey the color thermosensitive recording material 12 in the opposite directions. At the time of this conveyance, the trailing end of the color thermosensitive recording material 12 is guided to the retracting passage 81 side by the branch portion 80. In addition,
Since the optical fixing devices 32 and 33 are selectively positioned as close as possible to the pressing roller 20b of the second conveying roller pair 20, the unfixable portion and the uneven fixing portion are reduced,
The blank space resulting from this can be reduced.

When the color thermosensitive recording material 12 is fed in the reverse direction, the optical fixing devices 32 and 33 are switched. As shown in FIG. 4, the interlocking mechanism 36 rotates the motor to first rotate the swing frame 35 by 10 degrees counterclockwise as shown in (B). After this rotation, as shown in (C), the rotating frame 34 is rotated clockwise by 105 degrees. After this rotation, as shown in (D), the swing frame 35 is rotated clockwise by 10 degrees and returned to the original position. As a result, instead of the yellow light fixing device 32, the magenta light fixing device 33 is set at the fixing position.

When the heating element 18a passes the pressing start position of the color thermosensitive recording material 12, the first and second conveying roller pairs 16 and 20 are stopped. After that, the first and second conveying roller pairs 16 and 20 rotate forward to convey the color thermosensitive recording material 12 in the forward direction, and when the heating element 18a is positioned at the pressing start position, the thermal head 18 is again moved to the thermal recording position. Return to. When the tip of the recording area of the color thermosensitive recording material 12 reaches each heating element 18a, the thermal head 18 applies thermal energy corresponding to the magenta image to the magenta thermosensitive coloring layer 27 to perform thermal recording. Further, the magenta ultraviolet lamps 33a and 33b are turned on in synchronization with the thermal recording. The magenta UV lamps 33a and 33b irradiate the color thermosensitive recording material 12 with near-ultraviolet rays having a wavelength of about 365 nm, and fix the cyan thermosensitive coloring layer 26 so that magenta will not develop color during thermal recording.

When the magenta image is thermally recorded up to the rear end of the recording area of the color thermosensitive recording material 12, the pressing of the thermal head 18 is released and the first and second conveying roller pairs 16 and 20 are temporarily stopped. After that, as in the case of the yellow recording, the first and second conveying roller pairs 16, 20 are
Rotates in the opposite direction. For magenta fixing,
Since it is sufficient to give a light amount above a certain level, there is no problem of color unevenness due to over-fixing as in the case of yellow light fixing, and therefore it is not necessary to open / close the shutter plate 52 as in yellow recording.

Thereafter, cyan thermal recording is performed in the same manner. Even during the recording of the cyan image, the magenta ultraviolet lamp 33a is turned on to continue bleaching. When the thermal recording of the cyan image is completed, the first and second conveying roller pairs 16 and 2 are
0 continues to rotate, the color thermosensitive recording material 12 is sent to the paper discharge passage, and is discharged to a paper discharge tray (not shown). Even during this discharge, the magenta ultraviolet lamp 33 is used until the color thermosensitive recording material 12 is discharged from the optical fixing area.
a lights up. Therefore, the rear end of the color thermosensitive recording material 12 nipped by the conveying roller pair 20 during thermosensitive recording is also bleached. After this bleaching, FIG.
As shown in (A), the swing frame 35 and the rotating frame 34 are displaced, and the yellow fixing device 32 is set at the fixing position instead of the magenta fixing device 33.

In the above embodiment, the optical fixing device 32 is constructed by using the two ultraviolet lamps 32a and 32b.
In addition to this, the optical fixing device may be configured by using three or more ultraviolet lamps. Also in this case, when the tip of the shutter plate passes through the irradiation area of the UV lamp with high illuminance, the drive voltage is temporarily lowered to prevent over-fixing due to the high illuminance. , Make the distribution of integrated fixing light amount almost uniform.

Further, as shown in FIG. 11 (F), near the both ends of the fixing area LA of the optical fixing device 88, the illuminance is lowered because it is far from the ultraviolet lamp, and a uniform illuminance distribution cannot be obtained. Therefore, in order to compensate for the shortage of the integrated fixing light amount due to the insufficient illuminance on the right side, as shown in FIG.
As shown in (C), fixing light amount correction openings 92 and 93 are formed long in the width direction of the shutter plate 90 at positions corresponding to the insufficient illuminance portion on the shutter plate 90, and at the final stage of closing the shutter plate. Fixing light may be applied to the color thermosensitive recording material 12 through the correction openings 92 and 93. As a result, the integrated fixing light amount increases as indicated by CA3 and CA4 in (D).

Further, as shown in FIG. 7B, when the shortage of the integrated fixing light amount due to the left illuminance shortage portion is compensated, ultraviolet rays are emitted at the time when the tip of the shutter plate 90 reaches the shortage illuminance portion. It is advisable to raise the driving voltage of the lamps 85 and 86 to temporarily raise the illuminance. As a result, FIG.
As indicated by CA5 in (D), the integrated fixing light amount can be increased, and the integrated fixing light amount in the fixing area LA of the optical fixing device 88 can be made more uniform. The drive voltage is controlled by detecting the entry position of the shutter plate 90. In addition to this, a light-receiving opening is formed in the shutter plate, and the irradiation light entering the light-receiving sensor 89 through this light-receiving opening is narrowed down according to the entry position of the shutter plate, and the amount of light incident on the light-receiving sensor 89 is reduced. May be reduced. In this case, the illuminance control circuit that keeps the illuminance constant acts to increase the dimming amount, so that the illuminance of the ultraviolet lamps 85 and 86 can be increased. Also,
Instead of increasing the illuminance of the ultraviolet lamps 85, 86, the integrated fixing light amount may be increased by decreasing the closing speed of the shutter plate 90 immediately before closing.

Further, in the above embodiment, as shown in FIG. 2, the two optical fixing devices 32 and 33 are selectively set to the fixing position by using the swing frame 35 and the rotating frame 34. However, if there is no space constraint,
Only by rotating or reversing the rotating frame 34, each optical fixing device 3
2, 33 may be selectively set at the fixing position. Further, instead of using the rotating frame 34, each optical fixing device may be selectively set at the fixing position by a shift mechanism.

In the above embodiment, as shown in FIG.
The light receiving sensors 50a, 50b are connected to the respective ultraviolet lamps 32a, 3
Although it is arranged on the lower side of 2b, instead of this, as shown in FIG. 8 (A), the light receiving sensor 100 is arranged on the tip portion 101a of the shutter plate 101, and the ultraviolet lamps 102, 10 are arranged.
The illuminance in the reflector 104 of No. 3 may be measured. Further, as shown in FIGS. 8 and 9, the light receiving sensor 100 provided at the tip portion 101 a of the shutter plate 101.
Thus, the shutter plate 101 is closed in the fixing area LA while the ultraviolet lamps 102 and 103 are made to emit light with the maximum illuminance, and the illuminance distribution in the fixing area LA of the reflector 104 is measured. Then, the illuminance distribution and the shutter plate 10
The cumulative fixing light amount distribution is predicted from the closing speed of 1, and the driving voltage at the entrance position of the shutter plate 101 is calculated from the difference between the predicted cumulative fixing light amount distribution and the target cumulative fixing light amount, as shown in FIG. 8C. Ask. Then, the shutter plate 101
The ultraviolet lamps 102, 103 in synchronization with the closing operation of the
May be driven with this drive voltage to obtain a substantially uniform integrated fixing light amount. As a result, FIG.
Even if an optical fixing device in which the illuminance distribution is not uniform as shown in FIG.
As shown in (D), a substantially uniform integrated fixing light amount distribution can be obtained. Note that FIG. 9 shows a processing procedure for obtaining the drive voltage in the controller.

[0052]

According to the present invention, when the tip of the shutter plate passes through the irradiation area of the ultraviolet lamp of high illuminance among the fixing lamps, the ultraviolet lamp is dimmed by the amount of high illuminance. It is possible to eliminate uneven fixing light amount unevenness due to variations in illuminance. Therefore, the integrated fixing light amount distribution in the irradiation area of the fixing lamp can be made substantially uniform after the feeding of the recording material is stopped. As a result, when a plurality of fixing lamps are used, it is possible to reduce the influence of illuminance variations among the individual fixing lamps.

Further, a light receiving sensor is provided at the tip of the shutter plate, and the illuminance of each ultraviolet lamp is controlled so that the integrated fixing light amount distribution in the reflector is made uniform based on the signal from the light receiving sensor. Even if a non-uniform optical fixing device is used, a substantially uniform integrated fixing light amount distribution can be obtained.

[Brief description of the drawings]

FIG. 1A is a side view showing a main part of a yellow light fixing device of an optical fixing device for a color thermal printer of the present invention, and FIG. 1B is an example of an integrated fixing light amount distribution in a fixing area of the optical fixing device. The diagram and (C) are plan views showing the shutter plate.

FIG. 2 is a schematic diagram showing a main part of a color thermal printer.

FIG. 3 is a schematic view showing an example of a layer structure of a color thermal recording material used in a color thermal printer.

FIG. 4 is an explanatory diagram showing switching of the optical fixing device.

FIG. 5 is a flowchart showing a processing procedure in an illuminance measurement adjustment mode.

6A, 6B, 6C, and 6D are explanatory diagrams sequentially showing a yellow light fixing state after the feeding of the color thermosensitive recording material is stopped.

7A is a side view showing a main part of an optical fixing device in another embodiment, FIG. 7B is a diagram showing an example of an illuminance distribution in a reflector, and FIG. 7C is a plan view showing a shutter plate. ,
FIG. 3D is a diagram showing an example of an integrated fixing light amount distribution in the reflector.

FIG. 8A is a side view showing an essential part of an optical fixing device in another embodiment in which a light receiving sensor is provided at the tip of the shutter plate, and FIG. 8B is a diagram showing an example of illuminance distribution in the reflector. , (C) is a diagram showing an example of the drive voltage pattern of the ultraviolet lamp determined based on this illuminance distribution, (D)
FIG. 4 is a diagram showing an example of an integrated fixing light amount distribution in a reflector.

FIG. 9 is a flowchart showing a processing procedure for calculating the drive voltage of the ultraviolet lamp based on the illuminance distribution obtained from the light receiving sensor.

FIG. 10 is a schematic diagram showing a conventional example of a color thermal printer.

11A is a schematic view of an optical fixing device, FIG. 11B is a diagram showing an illuminance distribution in the ideal optical fixing device, and FIG. 11C is color heat sensitivity when the ideal optical fixing device is used. A diagram showing a fixing light amount distribution immediately after the feeding of the recording material is stopped, (D) is a diagram showing a fixing light amount distribution when the shutter plate is closed immediately after the feeding of the color thermosensitive recording material is stopped, and (E) is a shutter. A diagram showing an integrated fixing light amount when the plate is closed, (F) a diagram showing an example of an illuminance distribution in an actual optical fixing device, and (G) a lamp having a low illuminance in the actual optical fixing device. A diagram showing an example of the cumulative fixing light amount when the shutter plate closing speed is set, (H) is the cumulative fixing light amount when the shutter plate closing speed is set according to the lamp with high illuminance in the actual optical fixing device. It is a diagram showing an example.

[Explanation of symbols]

10, 32, 33, 88 Optical fixing device 12 Color thermal recording material 16, 20 Conveying roller pair 18 Thermal head 10a, 10b, 32a, 32b, 33a, 33b, 8
5, 86, 102, 103 Ultraviolet lamp 10c, 40, 41, 87, 104 Reflector 50a, 50b, 89, 100 Light receiving sensor 52, 90, 101 Shutter plate 57 Illuminance measuring circuit 58 Controller 59 Voltage control circuit 61 Shutter plate drive section 92,93 Opening for fixing light amount correction

Claims (5)

[Claims] 1. At least first to color different colors
While the color thermosensitive recording material on which the third thermosensitive coloring layer is layered is reciprocated, one type of thermosensitive coloring layer is selectively colored by the thermal head, and before the next thermosensitive coloring layer is colored An optical fixing device for a color thermal printer, which irradiates an electromagnetic ray peculiar to a thermosensitive color developing layer to optically fix the thermosensitive color developing layer, comprising a plurality of fixing lamps arranged in the feeding direction of the color thermosensitive recording material, and these fixing lamps. A reflector that reflects the electromagnetic radiation from the color thermosensitive recording material side to the color thermosensitive recording material side, and is formed longer than the optical fixing area by this reflector, and the feeding direction of the color thermosensitive recording material during optical fixing between the color thermosensitive recording material and the reflector. The movable shutter plate and the electromagnetic rays from the fixing lamp and the reflector are shielded immediately after the feeding of the color thermosensitive recording material is stopped near the end of the optical fixing. Thus, the shutter plate is provided with a shutter plate driving unit that closes the shutter plate by moving the shutter plate in the direction opposite to the feeding direction of the color thermosensitive recording material during optical fixing. An optical fixing device for a color thermal printer, which is characterized in that when the leading edge of the sheet passes, the ultraviolet lamp is dimmed by the amount of high illuminance so that the integrated fixing light amount distribution is made substantially uniform. 2. The optical fixing device for a color thermal printer according to claim 1, wherein the shutter plate is for correcting a fixing light amount by irradiating an electromagnetic ray from a fixing lamp to a portion where the fixing light amount is insufficient immediately before the shutter plate is completely closed. An optical fixing device for a color thermal printer, which is provided with an opening. 3. The optical fixing device for a color thermal printer according to claim 1, wherein the illuminance of the fixing lamp is increased near the completion of closing of the shutter plate to make the integrated fixing light amount distribution substantially uniform. Optical fixing device for color thermal printers. 4. The optical fixing device for a color thermal printer according to claim 1 or 2, wherein the closing speed of the shutter plate is reduced near the completion of closing the shutter plate to make the integrated fixing light amount distribution substantially uniform. An optical fixing device for color thermal printers. 5. At least first to different colors are developed.
While the color thermosensitive recording material on which the third thermosensitive coloring layer is layered is reciprocated, one type of thermosensitive coloring layer is selectively colored by the thermal head, and before the next thermosensitive coloring layer is colored An optical fixing device for a color thermal printer, which irradiates an electromagnetic ray peculiar to a thermosensitive color developing layer to optically fix the thermosensitive color developing layer, comprising a plurality of fixing lamps arranged in the feeding direction of the color thermosensitive recording material, and these fixing lamps. A reflector that reflects the electromagnetic radiation from the color thermosensitive recording material side to the color thermosensitive recording material side, and is formed longer than the optical fixing area by this reflector, and the feeding direction of the color thermosensitive recording material during optical fixing between the color thermosensitive recording material and the reflector. The movable shutter plate and the electromagnetic rays from the fixing lamp and the reflector are shielded immediately after the feeding of the color thermosensitive recording material is stopped near the end of the optical fixing. As described above, the shutter plate is moved in the direction opposite to the feeding direction of the color thermosensitive recording material at the time of optical fixing and is closed, and the light receiving for measuring the illuminance of each ultraviolet lamp provided at the tip of the shutter plate. An optical fixing device for a color thermal printer, comprising: a sensor; and an illuminance control unit that controls the illuminance of each ultraviolet lamp so that the integrated fixing light amount distribution in the reflector is made uniform based on a signal from the light receiving sensor. .