JPH091837A - 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 23a 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 the 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 lamp 32a having higher illuminance is disposed at the near position to the late 52. When the end 52a of the plate 52 is passed through the illuminating area LLA of the lamp 32a having low illuminance, the closing speed Vsb of the plate 52 is lowered as compared with the closing speed Vsb when passing the illuminating area HLA of the lamp 32a having high illuminance.

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. 6, 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 by the pair of transport rollers 2 is required, and this portion does not reach the optical fixing device, so that fixing cannot be performed, so that it 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 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 is different between the part that reaches the ultraviolet irradiation area first and the part that reaches the ultraviolet irradiation area later. There is unevenness in the amount of optical fixing inside.

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]

By the way, FIG. 7 (A)
As shown in FIG. 7, in the optical fixing device 10 including the ultraviolet lamps 10a and 10b and the reflector 10c, the uniform illuminance distribution as shown in FIG. 7B is ideal.
The illuminance distribution is as shown in (F). FIG.
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. For example, when the illuminance of the ultraviolet lamp 10a near the shutter plate side is low as shown in (F), the lamp 10a on the low illuminance side is shown in (G).
If the closing speed of the shutter plate is set according to the above condition, the over-fixed 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, it is affected by the magenta light fixing ultraviolet rays contained in the irradiation light of the yellow light fixing ultraviolet lamps 10a and 10b, and a part of the magenta heat-sensitive recording layer for the next heat recording is also fixed. Will end up. Therefore, in this over-fixed portion, the color development of magenta becomes insufficient, 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 high illuminance side, 2
The insufficient fixing light amount portion CUA1 occurs on the lamp side having a lower illuminance than that of the ideal state shown by the dotted line. 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.

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and when a plurality of fixing lamps are used, a color thermal printer for which the influence of the illuminance variation of each fixing lamp is reduced with a simple structure. It is an object to provide an optical fixing device.

[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 a direction opposite to the feeding direction of the recording material and closes, and arranges the plurality of fixing lamps in order of increasing illuminance from the shutter plate side. It is intended. Further, in the optical fixing device for a color thermal printer according to claim 2, the plurality of fixing lamps are arranged in order of increasing illuminance from the shutter plate side, and among these fixing lamps, the irradiation area of the fixing lamp on the lower illuminance side. When the front end of the shutter plate passes through the shutter plate, the closing speed of the shutter plate is lowered according to the decrease in illuminance to make the integrated fixing light amount distribution substantially uniform.

[0013]

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.

The plurality of ultraviolet lamps are arranged in order of increasing illuminance from the shutter plate side. Further, when the front end of the shutter plate passes through the illuminance area of the fixing lamp on the low illuminance side, the closing speed of the shutter plate is reduced corresponding to the decrease in illuminance. Therefore, the area of over-fixing is not generated, and the area of insufficient fixing light amount can be reduced, and a substantially uniform integrated fixing light amount can be obtained.

[0015]

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, the thermal head 18 has a large number of heating elements 18a arranged in a line. 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, 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 to 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, and the swing frame 35 is illustrated. 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 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 rotates counterclockwise by 10 degrees, and then as shown in (C), the swing frame 3 rotates.
4 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. Further, in order to return from the magenta light fixing state to the yellow light fixing state, the rotation or swing operation of each frame 34, 35 is performed as shown in FIGS. 4 (D), (C), (B) and (A). Be seen. 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 sensor 50 is arranged below the 33a and 33b.

The light receiving sensor 50 is composed of a well-known phototransistor, and the ultraviolet lamp 3 at the fixing position.
The irradiation light from 2a, 32b or 33a, 33b is photoelectrically converted. 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 sends it to the controller 58.
Based on this illuminance signal, the controller 58 controls the ultraviolet lamps 32a, 32b, 33a, 33b so that the illuminance of the ultraviolet lamps 32a, 32b, 33a, 33b becomes constant.
Drive voltage is obtained and sent to the voltage control circuit 59. The voltage control circuit 59 drives each of the ultraviolet lamps 32a, 32b, 33a, 33b based on this drive voltage. The illuminance measuring circuit 57, the controller 58, and the voltage control 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 closing speed of the shutter plate 52 is set based on the measured illuminances La and Lb of the ultraviolet lamps 32a and 32b. Further, as will be described later, of the two ultraviolet lamps 32a and 32b, the lamp 32 having a low illuminance is used.
When the front end 52a of the shutter plate 52 is located in the irradiation area LLA of b, the closing speed Vsb in this irradiation area is
However, it is made lower according to the amount of decrease in the illuminance of the lamp 32b. 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. 1B, the shutter plate 52
Is short in the width direction so as not to block the optical path of the light receiving sensor 50. Therefore, even when the shutter plate 52 is set to the closed position, the illuminance of each of the ultraviolet lamps 32a and 32b can be measured. In addition, each ultraviolet lamp 32a, 3 of the yellow light fixing device 32
2b are arranged side by side from the shutter plate side in descending order of illuminance in consideration of variations in illuminance of individual lamps.

The controller 58 is composed of a well-known microcomputer, and counts the number of motor drive pulses of a transport 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 controls the closing speed of the shutter plate 52 for each ultraviolet lamp 3.
It is changed according to the variation in illuminance of 2a and 32b. Therefore, the illuminances La and Lb of the ultraviolet lamps 32a and 32b are
Is measured, and the closing speed V of the shutter plate 52 is correspondingly measured.
An illuminance measurement adjustment mode for determining sa and Vsb is provided. 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.

In the illuminance measuring and adjusting mode, as shown in FIG. 2, the illuminance measuring circuit 57 first measures the illuminance of each of the ultraviolet lamps 32a and 32b of the yellow optical fixing device 32. In this measurement, only the lamp to be measured is turned on and the illuminances La and Lb of the ultraviolet lamps 32a and 32b are measured alternately. The measured values La and Lb are compared by the controller 58, and when the illuminance of the ultraviolet lamp 32a on the side closer to the shutter plate 52 is lower than that of the lamp 32b on the far side, display of lamp position change is displayed on the display 69. . In this case, the ultraviolet lamps 32a, 3
The position of 2b is manually exchanged so that the ultraviolet lamp on the side closer to the shutter plate 52 has a higher illuminance than that on the side farther. Further, when the illuminance of the ultraviolet lamp 32a near the shutter plate 52 is higher than that of the lamp 32b on the far side, the display of the lamp position change is not displayed on the display 69, and the shutter plate 52 is based on the measured illuminances La and Lb. The closing velocities Vsa and Vsb of the are calculated. The closing velocities Vsa and Vsb are read from the look-up table memory in the controller 58 based on the measured illuminances La and Lb.

The measured illuminances La and Lb of the ultraviolet lamps 32a and 32b and the shutter plate closing speed V in the irradiation areas LLA and HLA by the ultraviolet lamps 32a and 32b.
The relationship between sa and Vsb is obtained in advance by experiments or the like, and this is stored in the memory in a look-up table format. Therefore, as shown in FIGS. 1A and 1C, the irradiation area H by the lamp 32a on the high illuminance side is
In LA, the shutter plate 52 is closed at the closing speed of Vsa, and in the irradiation area LLA by the lamp 32b having low illuminance, the shutter plate 52 is closed at Vsb lower than Vsa.
Will be closed. Therefore, in the irradiation area LLA of the lamp 32b having low illuminance, the closing speed of the shutter plate 52 becomes Vsb corresponding to the amount of low illuminance, which is Vsa.
As shown in FIG. 1D, the cumulative fixing light amount increases by the amount CA1 corresponding to the lower closing speed.
Even in this area LLA, almost the same integrated fixing light amount as that in the irradiation area HLa of the lamp 32a having high illuminance is obtained, and the substantially uniform integrated fixing light amount distribution is obtained. If the lamp 32a with high illuminance is not on the shutter plate side, it is not possible to prevent over-fixing of the portion with high illuminance only by controlling the closing speed of the shutter plate.

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. 1C, the moving speed of the shutter plate 52 becomes Vsa while the tip 52a of the shutter plate 52 passes through the irradiation area HLA of the lamp 32a having a high illuminance on the side closer to the shutter plate 52. The lamp 52 having a low illuminance at the tip 52a of the plate 52
Vsb (Vsb (Vsb
≦ Vsa). Therefore, the yellow light fixing device 32
The integrated fixing light amount in the fixing area LA can be made substantially uniform. As a result, the amount of fixing light in the fixing area LA after the feeding of the recording material 12 is stopped is fixed with almost the same amount of light as that in other already fixed areas, and uneven fixing is eliminated.

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. In addition, the first and second
The pair of conveying rollers 16 and 20 rotate in the opposite direction to convey the color thermosensitive recording material 12 in the opposite direction. 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, the second conveying roller pair 20
Since the optical fixing devices 32 and 33 are selectively positioned as close as possible to the pressing roller 20b, the non-fixable portion and the non-uniform fixing portion are reduced, and the blank portion 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 FIG. 4 (B). After this rotation,
As shown in (C), turn the rotating frame 34 clockwise 1
Rotate 05 degrees. After this rotation, as shown in (D), the swing frame 35 is rotated clockwise by 10 degrees and returned to its 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 pressing start position of the color thermosensitive recording material 12 is again positioned at the heating element 18a, the first and second conveying roller pairs 16 and 20 are temporarily stopped. Then, the thermal head 18 returns to the thermal recording position again, and the first and second conveying roller pairs 16 and 20 rotate forward to convey the color thermosensitive recording material 12 in the forward direction. Color thermal recording material 1
When the tip of the second recording area reaches each heating element 18a,
The thermal head 18 applies thermal energy according to a magenta image to the magenta thermosensitive coloring layer 27 to perform thermal recording. In addition, in synchronization with the thermal recording, the magenta ultraviolet lamp 33a,
33b lights up. This magenta UV lamp 33
By the a and 33b, near-ultraviolet rays in the vicinity of 365 nm are applied to the color thermosensitive recording material 12, and the cyan thermosensitive coloring layer 26 is fixed so that magenta will not be colored during the next 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 apply a light amount above a certain level, there is no problem of color unevenness caused by uneven fixing as in the case of yellow light fixing, and therefore it is not necessary to open and 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,
20 continues rotating as it is, sends the color thermosensitive recording material 12 to the paper discharge passage, and discharges it to a paper discharge tray (not shown). Even during this discharge, the magenta ultraviolet lamp 3 is used until the color thermosensitive recording material 12 is discharged from the optical fixing area.
3a 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, each measured illuminance La,
The closing speeds Vsa and Vsb in the respective irradiation areas HLA and LLA were obtained for each Lb. In addition to this, Vsa was determined based on the standard maximum illuminance of the ultraviolet lamp used, and the value of La-Lb was determined. Vsb may be calculated based on

Further, 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. In this case, lamps with high illuminance are arranged in order from the side closer to the shutter plate, and the closing speed of the shutter plate when the tip of the shutter plate passes through the irradiation area by these lamps is calculated for each area,
The closing speed of the shutter plate is reduced according to the decrease in illuminance.

Further, as shown in FIG. 7F, a uniform illuminance distribution cannot be obtained near both ends of the fixing area LA of the optical fixing device 32. Therefore, in order to compensate for the shortage of the integrated fixing light amount due to the insufficient illuminance portion on the right side, a fixing light amount correction opening is formed long in the width direction of the shutter plate at a position corresponding to this insufficient illuminance portion. Then, at the end of the closing of the shutter plate, the color thermosensitive recording material may be irradiated with the fixing light from the correction opening. In addition, in order to compensate for the shortage of the integrated fixing light amount due to the insufficient illuminance on the left side, the illuminance is temporarily increased by raising the drive voltage of the ultraviolet lamp when the tip of the shutter plate reaches the insufficient illuminance. It should be set to. As a result, the fixing area LA of the optical fixing device 32 is
In this case, the integrated fixing light amount can be made more uniform.

Further, in the above embodiment, as shown in FIG. 2, the two optical fixing devices 32 and 33 are selectively set at 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.

[0046]

According to the present invention, since a plurality of fixing lamps are arranged from the shutter plate side in the descending order of illuminance, by controlling the closing speed of the shutter plate, it is possible to prevent over-fixing of the illuminant portion. it can. In addition, a plurality of fixing lamps are arranged from the shutter plate side in descending order of illuminance, and when the tip of the shutter plate passes through the irradiation area of the fixing lamp on the lower illuminance side of these fixing lamps, Accordingly, the closing speed of the shutter plate is lowered, so that the integrated fixing light amount in the irradiation area of the fixing lamp can be made substantially uniform after the feeding of the recording material is stopped.
That is, when a lamp with low illuminance is arranged on the side close to the shutter plate, if the closing speed of the shutter plate is lowered to correct this decrease in illuminance, irradiation of the lamp with high illuminance at a position far from the shutter plate is performed. In the present invention, since the fixing lamps are arranged in the order of increasing illuminance from the shutter plate side, when fixing the irradiation area by the lamp with low illuminance, this area is used as the shutter plate. By lowering the closing speed when the sheet passes through according to the amount of decrease in illuminance, it is possible to eliminate the insufficient fixing light amount portion without generating an overfixing area. Therefore, a substantially uniform integrated fixing light amount can be obtained.
As a result, when a plurality of fixing lamps are used, it is possible to reduce the influence of the illuminance variation of each fixing lamp with a simple configuration.

[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, FIG. 1B is a plan view showing a shutter plate, and FIG. 1C is a fixing area by a reflector. A diagram showing the closing speed of the shutter plate in
(D) is a diagram showing an integrated fixing light amount distribution in a fixing area of this optical fixing device.

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.

FIG. 6 is a schematic view showing a conventional example of a color thermal printer.

7A is a schematic diagram of an optical fixing device, FIG. 7B is a diagram showing an illuminance distribution in the ideal optical fixing device, and FIG. 7C 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 Optical fixing device 12 Color thermal recording material 16, 20 Conveying roller pair 18 Thermal head 10a, 10b, 32a, 32b, 33a, 33b UV lamp 10c, 40, 41 Reflector 50 Light receiving sensor 52 Shutter plate 57 Illuminance measurement Circuit 58 Controller 59 Voltage Control Circuit 61 Shutter Plate Drive Unit

Claims (2)

[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. In this way, the shutter plate is provided with a shutter plate drive unit that is closed by moving the shutter plate in the direction opposite to the feeding direction of the color thermosensitive recording material at the time of optical fixing, and the plurality of fixing lamps are arranged from the shutter plate side in descending order of illuminance. An optical fixing device for a color thermal printer, which is characterized in that 2. The method according to claim 1, wherein the first color and the second color are 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. In this way, the shutter plate is provided with a shutter plate drive unit that closes by moving the shutter plate in a direction opposite to the feeding direction of the color thermosensitive recording material during optical fixing, and arranges the plurality of fixing lamps from the shutter plate side in descending order of illuminance. , Among these fixing lamps, when the tip of the shutter plate passes the irradiation area of the fixing lamp on the low illuminance side, the closing speed of the shutter plate is lowered according to the decrease in the illuminance, and the integrated fixing light amount distribution is An optical fixing device for a color thermal printer, which is almost uniform.