JPH07149021A - Printing apparatus - Google Patents

Abstract

PURPOSE:To accurately discriminate the terminal of an ink ribbon even when both of a color ink ribbon and a monochromatic ink ribbon are used by providing a light transmissivity sensor to discriminate and detect the light transmissivity of the ink ribbon. CONSTITUTION:Two ribbon kind discriminating projections 105, 106 are provided to a color ink ribbon cassette 101 and one ribbon kind discriminating projection is provided to a monochromatic ink ribbon cassette. A discriminating press switch 21 having a plurality of press elements 79, 80 is provided to a cassette holder 63 corresponding to the discriminating projections 105, 106. On the basis of the output signal of the press switch, it is discriminated which of the color ink ribbon cassette 101 and the monochromatic ink ribbon cassette is mounted in a signal processing circuit. A light transmissivity sensor for detecting the marks of the cassettes is attached on the side of a printer block and the terminal of the ink ribbon is detected from the output of the sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an ink ribbon composed of a plurality of color inks such as yellow (Y), magenta (M), and cyan (C) deposited on a film to make paper, etc. The present invention relates to a printing apparatus that prints on a printing material.

[0002]

2. Description of the Related Art Conventionally, a printing apparatus applying the so-called silk screen printing principle has been proposed. This printing apparatus prints using an original screen made of a material having a property of blocking wet ink. The original screen has a portion for transmitting the wet ink according to an image to be printed. In this printing apparatus, the original screen is placed on a sheet of material to be printed, and a wet ink of a desired color is applied from above the original screen, so that the image formed on the original screen is Printed on paper.

A plurality of types of original image screens are prepared, and a wet ink of a different color is used in accordance with the images formed on these original image screens to print on one sheet of paper in a superimposed manner to form a color image. Printing can also be performed.

[0004]

By the way, in the above-described printing apparatus, the printing procedure and operation are troublesome, and the quick printing work cannot be performed. That is, in this printing apparatus, since printing is performed using the wet ink, it takes time to dry the ink forming the printed image, and it is not only necessary to handle the paper after printing, but It is not possible to immediately print with another color after printing with a color.

Further, in this printing apparatus, since the image is formed by using the above-mentioned original screen, it is difficult to correct the image to be printed, and further, the fine image cannot be printed well.

Therefore, the present invention is proposed in view of the above circumstances, and it is an object of the present invention to provide a printing apparatus which is small in size, simple, and easy in printing operation, and which can print a good image. To aim.

[0007]

In order to solve the above-mentioned problems and achieve the above-mentioned object, an image-printing apparatus according to the present invention uses an ink ribbon to press the ink ribbon onto a material to be printed by a thermal head. A printing apparatus for printing by transferring to a printing material, comprising a plurality of identification pressing switches corresponding to one or a plurality of ribbon type identification projections provided on a ribbon cassette containing the ink ribbon, and the ribbon. A light transmittance sensor for detecting the light transmittance of the ink ribbon housed in the cassette in the vicinity of the thermal head, and the ribbon cassette is mounted and mounted depending on the pressing operation state of each pressing switch. Ink ribbon near the thermal head is determined based on the output signal of the light transmittance sensor as well as the type of ribbon cassette is determined. A control means for determining the light transmittance, wherein the control means is a state in which the ink ribbon near the thermal head substantially blocks light when the mounted ribbon cassette accommodates a color ink ribbon. Is determined to be the end of the ink ribbon, and when the attached ribbon cassette accommodates a monochrome ink ribbon, the ink ribbon near the thermal head emits almost all light. When the transparent state is reached, the end of the ink ribbon is determined.

[0008]

In the printing apparatus according to the present invention, the control means is in a state in which the ink ribbon near the thermal head substantially blocks light when the mounted ribbon cassette accommodates a color ink ribbon. When it is determined that it is the end of the ink ribbon, when the attached ribbon cassette accommodates a monochrome ink ribbon, the ink ribbon near the thermal head transmits almost all light. Since the end of the ink ribbon is determined when the state is reached, the end of the ink ribbon can be accurately determined regardless of whether a color ink ribbon or a monochrome ink ribbon is used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

[1] Outline of Apparatus In a printing apparatus according to the present invention, a thermal head presses an ink ribbon onto the surface of a sheet to be printed, and the ink of the ink ribbon is transferred to the sheet. This is a printing apparatus for printing. As will be described later, the above-mentioned ink ribbon is coated with ink of each color such as yellow (Y), magenta (M), cyan (C), black, gold, and silver on a base film made of a synthetic resin material or the like. It has been configured.

As shown in FIG. 1, this printing apparatus has an outer casing 1. As shown in FIG. 2, a signal processing circuit 14 serving as control means and an image memory 15 connected to the signal processing circuit 14 are built in the outer housing 1. An image signal is input to the signal processing circuit 14 via the pressure sensitive board 2.

The pressure sensitive board 2 is, as shown in FIG.
It is formed in a substantially rectangular flat plate shape and is arranged on the front side upper surface portion of the outer housing 1. The pressure-sensitive board 2 has a large number of pressure-sensitive elements arranged in a matrix on the main surface portion. The pressure-sensitive board 2 is configured to output a signal indicating the position of the pressed portion on the pressure-sensitive board 2 when the main surface portion is pressed with a pressing force equal to or larger than a predetermined pressing force. Therefore, the output signal of the pressure-sensitive board 2 becomes a signal indicating an image formed by the portion of the pressure-sensitive board 2 to which the pressing force is applied. The pressing force is applied to the pressure-sensitive board 2 by using a rod-shaped member having a slightly pointed tip portion and bringing the tip portion into contact with the main surface portion of the pressure-sensitive board 2.

An image signal is also supplied to the signal processing circuit 14 through the image scanner 203 and the input terminal 13. The signal processing circuit 14 causes the image monitor 201 to display an image via the video cable 9.
The signal processing circuit 14 is used in the printer block 2
0 is controlled to print an image according to the image signal stored in the image memory 15.

The printer block 20 is housed in the rear portion of the outer casing 1, as shown in FIG. A color ink ribbon cassette 101 shown in FIG. 22 or a monochrome ink ribbon cassette 102 shown in FIG. 23 is attached to the printer block 20.

[2] Structure of Ink Ribbon Cassette As shown in FIG. 22, the color ink ribbon cassette 101 used for color printing has a pair of rotatable ribbon reels and a color ink ribbon 102 housed in the cassette. Is configured. This color ink ribbon 102 has one end side hooked on one ribbon reel and is wound around this one ribbon reel, and the other end side hooked on the other ribbon reel. Both sides of the portion of the color ink ribbon 102 extending between the ribbon reels face the outside of the cassette. The color ink ribbon 102 is wound on the other ribbon reel by rotating the other ribbon reel.

The pair of ribbon reels are provided with engagement holes 110, 110 for rotating the ribbon reels. These engagement holes 110, 110 are formed at one end of each of the ribbon reels, are located at the front end of the color ink ribbon cassette 101 in the direction of insertion into the printing apparatus, and face the outside of the cassette. .

The color ink ribbon 102 is shown in FIG.
As shown in FIG. 7, a film base made of a synthetic resin material is coated with inks of Y (yellow), C (cyan), and M (magenta) colors. In this color ink ribbon 102, Y (yellow), C (cyan), and M (magenta) regions are formed alternately.
Marks 108 and 109 for cueing are provided between the areas. The mark 108 in front of Y is each color Y, C,
It indicates that the start position of a set of printing areas made of M is longer than the other marks 109.

The color ink ribbon cassette 101 includes first and second ribbon type identification protrusions 105 and 106.
Is provided. These identification protrusions 105 and 106 are
The color ink ribbon cassette 101 is disposed on the rear side in the insertion direction of the printing apparatus and in the vicinity of the ribbon reel which is the lower side when the color ink ribbon cassette 101 is inclined and held in the printing apparatus. Further, a hooking protrusion 111 is provided at a rear side in the insertion direction of the color ink ribbon cassette 101 with respect to the printing apparatus and at a substantially central position of an upper surface portion. This hanging projection 111
Is to be held in the mounted state in the printing apparatus.

As shown in FIG. 23, the monochrome ink ribbon cassette 103 used in the case of monochrome printing is constructed by accommodating a pair of rotatable ribbon reels and a monochrome ink ribbon 104 in the cassette.
The monochrome ink ribbon 104 has one end side hooked on one ribbon reel and is wound around the one ribbon reel, and the other end side hooked on the other ribbon reel. Both sides of the portion of the monochrome ink ribbon 104 extending between the ribbon reels face the outside of the cassette. The monochrome ink ribbon 104 is
By rotating the other ribbon reel,
The other ribbon reel is wound up.

The pair of ribbon reels are provided with engagement holes 110, 110 for rotating the ribbon reels. These engagement holes 110, 110 are formed at one end of each of the ribbon reels, are located at the front end of the monochrome ink ribbon cassette 103 in the insertion direction of the printing device, and face the outside of the cassette. .

The monochrome ink ribbon 104 is formed by coating a film base made of a synthetic resin material with ink of any one of gold color, silver color and black color.

The monochrome ink ribbon cassette 103
Is provided with only the first ribbon type identification protrusion 107. The identification protrusion 107 is the first ribbon type identification protrusion 1 in the color ink ribbon cassette 101.
It is formed similarly to 05. Further, the hooked protrusion 111 is projected at the rear side in the insertion direction of the monochrome ink ribbon cassette 103 with respect to the printing device and at a substantially central position of the upper surface portion.

[3] Structure of Printer Block The printer block 20 has a paper feeding mechanism 16, a ribbon feeding mechanism 17, a head moving mechanism 18, and a thermal head 19, as shown in FIGS. Composed.

(1) Structure of Paper Feeding Mechanism As shown in FIGS. 4, 6 and 21, the paper feeding mechanism 16 is rotatably mounted on the chassis 29 fixedly arranged in the outer casing 1. It has a feed roller 64 arranged. The feed roller 64 has a support shaft portion and an abutting member formed of a material having a large friction coefficient such as a grindstone and externally fitted to the support shaft portion and covering the peripheral surface portion of the support shaft portion. Is configured. This feed roller 64
Is rotatably supported at both ends of the support shaft portion by support members provided on the front end side and the rear end side of the chassis 29.

The feed roller 64 is shown in FIG.
As shown in FIG. 1, the feed motor 4 attached to the front side wall portion 31 erected on the front side edge portion of the chassis 29.
4, the rotary operation is performed via the first and second transmission gears 81 and 82, the timing belt 83, and the driven gear 84. That is, a drive gear is attached to the drive shaft of the feed motor 44. The drive shaft has the first side wall 31 rotatably attached to the front side wall 31.
Of the transmission gear 81. This first transmission gear 8
The first transmission gear 82 is coaxially formed on the first transmission gear 1. The timing belt 83 is wound around the second transmission gear 82. The timing belt 83 is wound around the driven gear 84 attached to the front end side portion of the support shaft portion of the feed roller 64 protruding forward of the front side wall portion 31.

A pinch roller 65 is pressed against the feed roller 64. The pinch roller 65 is configured to have a support shaft portion and a contact portion that is formed of a material such as rubber into a cylindrical shape and is externally fitted to the support shaft portion. The pinch roller 65 is parallel to the feed roller 64 and is arranged above the feed roller 64. As shown in FIGS. 16 and 17, the pinch roller 65 includes a pair of support arm members 7 rotatably arranged on the front and rear sides of the chassis 29.
Both ends of the support shaft are rotatably supported by 6, 6 and can be operated to approach and separate from the feed roller 64. The support arm members 76, 76 are rotatably disposed via support shafts 77, 77, respectively, and the support shaft 77 is interlocked with the movement operation of the thermal head 19 as described later. , 77 around.

In this printing apparatus, the paper is nipped by the feed roller 64 and the pinch roller 65, and is fed by rotating the feed roller 64.

An edge sensor (optical sensor) 32 for detecting the trailing edge of the paper is disposed near the feed roller 64. The output signal of the edge sensor 32 is supplied to the signal processing circuit 14 as shown in FIG. That is, the trailing edge of the sheet is detected by the edge sensor 32, and the position in the printing apparatus is detected. The feed motor 44 is controlled by the signal processing circuit 14 based on the output signal of the edge sensor 32, and feeds the paper while controlling the position of the paper.

(2) Structure of Ribbon Feeding Mechanism The ribbon feeding mechanism 17 includes the above ribbon cassettes 10.
1, 103, the engaging holes 110, 110 of the pair of reels
It has a winding reel shaft 33 and a rewinding reel shaft 34 which are inserted and engaged correspondingly to. These winding and rewinding reel shafts 33 and 34 are provided on a front side wall portion 31 of the chassis 29 via a pair of support shafts which are planted rearward,
Each is rotatably mounted.

On the chassis 29, a cassette holder 63 is arranged at the rear side of the reel shafts 33, 34. The cassette holder 63 is formed in a substantially housing shape with an open rear side so that the ribbon cassettes 101 and 103 can be inserted from the rear side, and extends between the ribbon reels of the ink ribbons 102 and 104. Openings are provided in the upper and lower surface portions of the central portion so that both surface sides of the portion are exposed to the outside. The front end side of the cassette holder 63 is open so that the reel shafts 33 and 34 can be inserted into the cassette holder 63. The front end side of the cassette holder 63 is supported by the front side wall portion 31 and the rear end side thereof is supported by the rear side wall portion 30 of the chassis 29. This rear side wall portion 30
Are erected from the rear end edge of the chassis 29 and face each other in parallel to the front side wall portion 31.

The cassette holder 63 is provided with a lock member 23 for locking the locked projection 111. The lock member 23 is movably arranged on the rear side of the cassette holder 63 and above the opening portion into which the ribbon cassettes 101 and 103 are inserted. The lock member 23 holds the ribbon cassettes 101 and 103 in the state of being inserted into the cassette holder 63 by locking the hooked projections 111 of the ribbon cassettes 101 and 103 inserted into the cassette holder 63. To do. Further, the lock member 23 is moved to release the hooking to the hooked projection 111, so that the ribbon cassettes 101 and 103 can be taken out from the cassette holder 63. Ribbon cassettes 101, 10 inserted in the cassette holder 63
2 is held in the inserted state by the lock member 23, and the reel shafts 33 and 34 are inserted into and engaged with the engagement holes 110 and 110, respectively.

Further, the cassette holder 63 has a structure shown in FIG.
8 and FIG. 19, as shown in FIG.
A pressing switch 21 for identification having a plurality of pressing elements 79, 80 corresponding to 06, 107 is provided. The signal processing circuit 14 can determine whether the ribbon cassettes 101 and 103 have been mounted and the type of the ribbon cassette that has been mounted, depending on the pressing operation state of the pressing switch 21.

An opening which can be opened and closed by the lid 11 is formed on the rear surface of the outer casing 1 so that the rear end of the cassette holder 63 is exposed to the outside on the rear side. ing. The ribbon cassettes 101 and 103 are inserted into the cassette holder 63 through this opening.

As shown in FIGS. 4 and 9, the reel shafts 33 and 34 are selectively rotated by a reel motor 35 attached to the front side wall portion 31 via a plurality of transmission gears. Operated.

That is, the worm gear 36 is attached to the drive shaft of the reel motor 35. A worm wheel 37 rotatably attached to a support plate 70 attached to the reel motor 35 via a spindle 94 meshes with the worm gear 36. A transmission gear 69 is coaxially and integrally formed with the worm wheel 37. The transmission gear 69 has the support shaft 9
A swinging gear 38 arranged on a rotating arm 68 rotatably supported by 4 meshes with the rotating arm 68. The swing gear 38 is rotatably attached to the rotating arm 68 via a support shaft 95. This swing gear 38
A friction member 71 is interposed between the rotary arm 68 and the rotary arm 68. The transmission gear 69 is the swing gear 3
When 8 is rotated, the swinging gear 38 causes a load of rotation of the friction member 71 on the rotating arm 68, so that the rotating arm 68 is rotated.

Therefore, when the worm wheel 37 rotates clockwise as indicated by arrow M in FIG. 9, the pivot arm 68 is pivoted clockwise as indicated by arrow J in FIG. Is engaged with one reversing gear 41.
Further, when the worm wheel 37 rotates counterclockwise as indicated by arrow N in FIG. 9, the pivot arm 68 is pivoted counterclockwise as indicated by arrow H in FIG. The reverse gear 39 is meshed.

The one reversing gear 41 is rotatably attached to the front side wall portion 31 via a support shaft 96, and the winding reel shaft 3 is provided on the base end side of the winding reel shaft 33.
3 is meshed with a winding reel gear 42 integrally attached to the winding reel gear 42. Support shaft 9 supporting one of the reversing gears 41
Brake arm 43 is rotatably attached to 6 as shown in FIGS. 11 to 13. The brake arm 43 is provided at the tip end side portion thereof with the winding reel gear 4
It has a hooking protrusion that prevents the rotation of 2. The brake arm 43 is in sliding contact with the one reversing gear 41 via a friction member, and is rotated following the rotation direction of the one reversing gear 41.

When the swing gear 38 meshes with the one reversing gear 41, the one reversing gear 41
Is rotated clockwise as indicated by arrow G in FIGS. 9 and 11,
The winding reel gear 42 is indicated by an arrow F in FIGS. 9 and 11.
As shown by, the ribbon reel engaged with the winding reel shaft 33 rotates the ink ribbons 102 and 104 in the winding direction. At this time, the brake arm 43 is rotated following the one reversing gear 41, as shown by an arrow O in FIG. 11, to separate the latching protrusion from the winding reel gear 42.

The other reversing gear 39 is rotatably attached to the front side wall portion 31 via a support shaft, and is integrally attached to the rewind reel shaft 34 on the base end side of the rewind reel shaft 34. The rewind reel gear 40 is meshed with the rewind reel gear 40. The swing gear 38 is the other reverse gear 39.
, The other reversing gear 39,
As shown by an arrow L in FIG. 9, the rewind reel gear 40 is rotated counterclockwise as indicated by an arrow K in FIG. 9 by a ribbon reel engaged with the rewind reel shaft 34, and the ink ribbons 102, 104 are shown. Rotate in the direction to rewind.

As described above, the ink ribbons 102, 10 are
4 is rewound, the winding reel gear 42 moves the ink ribbons 102 and 104, as shown in FIG.
As a result, as shown by arrow Q in FIG. 12, the respective ink ribbons 102 and 104 are rotated in the winding direction, and the one reversing gear 41 is rotated counterclockwise as shown by arrow S in FIG. Rotate. When the one reversing gear 41 is rotated counterclockwise, the brake arm 43 moves to the position shown in FIG.
2 As indicated by a middle arrow R, the hooking protrusion is rotated in a direction toward the winding reel gear 42, and the winding reel gear 42 is hooked by the hooking protrusion.

Therefore, the ribbon reel engaged with the rewinding reel shaft 34 becomes the ink ribbons 102, 10.
When 4 is rotated in the rewinding direction, the ink ribbons 102 and 104 are not rewound by the ribbon reel, and the ink between the ribbon reel and the ribbon reel engaged with the winding reel shaft 33 is rewound. Ribbon 1
The tension of 02, 104 is increased. The reel shafts 33 and 34 are supported by the support shafts via a clutch member and generate a constant load when rotated by an external force. It is designed to maintain the tension of.

(3) Structure of Head Moving Mechanism As shown in FIGS. 4 and 5, the head moving mechanism 18 has a support block 47 arranged on the chassis 29.
The head moving motor 45 attached to the first
The pair of head arms 28, 28 supporting the thermal head 19 are configured to be rotated via the second worm gears 51, 53 and the cam gear 48.
The support block 47 is formed by bending a flat plate member into a substantially U shape.

The first worm gear 51 is attached to the drive shaft of the head moving motor 45. A worm wheel 52 rotatably supported by the support block 47 meshes with the first worm gear 51. The second worm gear 53 is coaxially and integrally arranged on the worm wheel 52.
The cam gear 48 has a gear portion forming a worm wheel on the outer peripheral surface thereof, and an engagement pin 49 on the main surface portion.
Are provided so as to project, and are rotatably supported by the support block 47 via a support shaft 46. The cam gear 48 is attached to one end of the support shaft 46, and a cam plate paired with the cam gear 48 is attached to the other end.

The head arms 28, 28 are rotatably supported at their base end sides with respect to the support block 47 via a support shaft 55. A pair of limiter arms 50, 50 are provided on the support shaft 55 so as to form the head arms 2.
Corresponding to Nos. 8 and 28, they are rotatably attached.
These limiter arms 50, 50 are linked to the head arms 28, 28 via first and second limiter springs 57, 58, respectively. That is, the first spring retaining piece 61 on the base end side of the head arm 28 and the first spring retaining piece 6 on the front end side of the limiter arm 50.
The first limiter spring 57 is stretched between 0 and 0. Further, the second limiter spring 58 is stretched between the second spring retaining piece 62 on the base end side of the head arm 28 and the second spring retaining piece 59 on the front end side of the limiter arm 50. It is hung. Each of these limiter springs 57,
58 is disposed above the support shaft 55, and the head arm 28 is connected to the limiter arm 50.
In contrast, the front end side is urged to rotate in the direction of being directed downward.

Engaging slits 54, 54 are provided on the rear end sides of the limiter arms 50, 50. An engaging pin 49 of the cam gear 48 and an engaging pin of the cam plate are correspondingly inserted and engaged in the engaging slits 54, 54. That is, when the cam gear 48 and the cam plate are rotated, the limiter arms 50, 50 are rotated.
Together with the head arms 28, 28,
It is rotated about 5 times.

The positioning of the support block 47 on the chassis 29 is performed by the pair of holding pieces 9 projecting from the both ends of the support shaft 55 on the chassis 29.
It is carried out by holding it at 2, 92. Each of the holding pieces 92, 92 has a recess at the upper end side into which the support shaft 55 is fitted and engaged.

The operation pins 90, 90 are provided on the head arms 28, 28 at positions slightly above the support shaft 55.
have. These operation pins 90, 90 are engaged with engaging piece portions 91, 91 of a pair of pressing levers 72, 72 slidably arranged on the chassis 29 in the same direction as the feeding direction of the sheet 202. There is. The pressing lever 7
2, 72 are the pinch rollers 65 at one end side portion.
Is engaged with the pair of support arm members 76, 76 for supporting the above, and has the engaging piece portions 91, 91 on the other end side. These engaging piece portions 91, 91 have recesses on the upper end side into which the operation pins 90, 90 are fitted and engaged. That is, each of the pressing levers 72, 72 is slid toward one end side as shown by an arrow W in FIG. 17 when the head arms 28, 28 are rotated in a direction in which the front end side is downward.

Each of the support arm members 76, 76 is shown in FIG.
6 and FIG. 17, the pinch roller 65 is moved to the feed roller 64 by a tension coil spring 78.
When the pressing levers 72, 72 are located on the other end side, the pressing levers 72, 72 resist the urging force of the tension coil spring 78, and The pinch roller 65 is held in a state of being separated from the feed roller 64. Therefore, when the pressing levers 72, 72 are slid toward the one end side, the supporting arm members 76, 76 are rotated by the biasing force of the tension coil spring 78,
As shown by an arrow V in FIG. 17, the pinch roller 65 is pressed against the feed roller 64.

Further, one end of each of the pressing levers 72, 72 faces a pressed piece portion 75 of a positioning member 73 described later.

(4) Operation of Thermal Head The thermal head 19 includes the head arms 28,
The head arms 28, 28 are supported so as to be passed between the tip ends of the head arms 28, 28. The thermal head 19 is formed in an elongated shape having a length substantially corresponding to the widths of the ink ribbons 102 and 104, and has heating elements arranged in a line in the longitudinal direction. These heating elements are
Heat is generated by being individually controlled according to the print image.

The thermal head 19 contacts the platen roller 66 rotatably mounted on the chassis 29 as shown in FIG. 8 when the head arms 28, 28 are rotated. It is moved and operated in the direction of separating. The platen roller 66 is the feed roller 6 described above.
4 are parallel to each other and are rotatably supported on both ends of the chassis 29. This platen roller 6
6 is arranged at a position substantially in the middle of each ribbon reel of the ribbon cassettes 101 and 103 mounted on the cassette holder 63.

The thermal head 19 includes the limiter arms 50, 50 and the head arms 28, 28.
After being rotated by the cam gear 48 and the cam plate to come into contact with the platen roller 66, the limiter arms 50, 50 are further rotated in the same direction, so that the limiter springs 57, 58 are rotated. It is pressed against the platen roller 66 by the urging force of. At this time,
The thermal head 19 has its longitudinal direction parallel to the axial direction of the platen roller 66.

The force with which the thermal head 19 is pressed against the platen roller 66 by the urging force of the limiter springs 57 and 58 is about 5 kg. The reduction ratio by each of the worm gears 51 and 53 is about 560: 1. Further, the head arms 28, 28 are integrally formed of aluminum and have a function of a heat sink that radiates heat generated by the thermal head 19.

The head arm 28 is provided with a head-out sensor 93 which is a light transmittance sensor for detecting the marks 108 and 109 of the color ink ribbon 104. The output signal of the head search sensor 93 is supplied to the signal processing circuit 14 as shown in FIG. The signal processing circuit 14 determines the light transmittance of the ink ribbon in the vicinity of the thermal head 19 according to the output signal of the head-up sensor 93.

The thermal head 19 shown in FIG.
As shown in FIG. 6, with respect to the platen roller 66 that holds the paper 202 in cooperation with the thermal head 19, the platen roller 66 is rearward with respect to the traveling direction of the paper 202 at the time of printing, and is indicated by an arrow θ in FIG. It is pressed against a position inclined by a predetermined angle. This angle θ is about 5 to 15 degrees. The running direction of the paper 202 during printing is a direction in which the paper 202 is pulled out by the feed roller 64 and the pinch roller 65 from between the thermal head 19 and the platen roller 66, and is indicated by an arrow B in FIG. It is in the same direction as the discharge direction of the paper 202 from this printing apparatus.

A holding plate 67 is rotatably attached to an edge of the cassette holder 63 on the lower surface side on the rewind reel shaft 34 side. The holding plate 67 has a length slightly longer than the width of the ink ribbons 102 and 104, has one side edge supported, and extends into the opening on the lower surface side of the cassette holder 63. It can be rotated in the vertical direction. When the printing is performed, the holding plate 67 is provided with the ink ribbon 1 as shown in FIG.
No. 02, 104 and the above-mentioned paper 202, and the ink ribbon 1
The parts on the side of 02, 104 are pressed and rotated to hold the paper 202 in a direction away from the ink ribbons 102, 104.

(5) Paper Supply and Discharge In this printing apparatus, the paper 202 is passed through the opening 12 formed in the side surface of the outer casing 1 as shown by arrow A in FIG. , And is inserted into the supply hole 26 of the printer block 20.

Inside the supply hole 26, as shown in FIGS. 3, 6 and 7, one side edge portion of the supply hole 26 facing outward is rotatably supported. As shown by D, a guide plate 25 is provided which is urged to rotate in a direction in which the other side edge portion is directed upward. The guide plate 25 is used for the paper 2
When 02 is supplied, the sheet 202 is pressed by the sheet 202 and rotated downward as shown by an arrow E in FIG. 7 against the biasing force. When the paper 202 is discharged as indicated by the arrow C in FIG. 7, the guide plate 25 indicates the position at which the paper 202 is supplied as indicated by the arrow B in FIGS. 6 and 7. It guides to a different position, that is, the discharge hole 27 which is the lower side of the guide plate 25.

An edge sensor (optical sensor) 32 for detecting the trailing edge portion of the paper 202 is disposed on the inner side of the supply hole 26 of the paper 202 into the printer block 20. The signal processing circuit 14 carries out the conveyance operation and the printing operation of the sheet 202 with the trailing edge position of the sheet 202 detected by the edge sensor 32 as a reference.

Further, as shown in FIG. 14, a positioning member 73 that comes into contact with the front edge portion of the paper 202 is provided on the inner side of the supply hole 26 of the paper 202 into the printer block 20. There is. This positioning member 73 is
It is rotatably supported by the support shaft 74, and the contact portion with respect to the sheet 202 can be moved forward and backward with respect to the entry path of the sheet 202. The positioning member 73 is moved by an urging member (not shown) as shown by an arrow T in FIG.
The contact portion is rotationally urged in a direction in which the sheet 202 enters the regulation of entry, and is positioned at the initial position. The positioning member 73 positions the front end of the sheet 202 inserted in the supply hole 26,
The inclination of the sheet 202 with respect to the conveying direction by the feed roller 64 and the pinch roller 65 is restricted.
The abutting portions of the positioning member 73 are arranged in pairs on both ends of the feed roller 64, and the paper 202
It is adapted to be in contact with both side portions of the front end portion of the.

The positioning member 73 has a pressed piece 75 facing one end of each of the pressing levers 72, 72. The positioning member 73 is interlocked with the operation of moving the thermal head 19 to the platen roller 66 side, and is pressed by the pressing levers 72, 72 as shown by an arrow U in FIG. By pressing and rotating the sheet, the sheet 202 can be conveyed as shown in FIG.

[4] Operation of Printing Apparatus When performing color printing in this printing apparatus, the color ink ribbon cassette 101 shown in FIG. 22 is mounted. The mounting of the color ink ribbon cassette 101 is determined by the signal processing circuit 14 via the pressing switch 21.

In the initial state, the head arms 28, 28 are rotated upward, and the thermal head 19 is initially separated from the color ink ribbon 102 shown in FIG. 8A. In position. And
When the print start button 4 is pressed, the thermal head 19 is rotated by the rotation of the head arms 28, 28.
The mark detection position is shown by (B) in FIG. At this time, the thermal head 19 is in contact with the color ink ribbon 102. Here, the signal processing circuit 1
4 causes the color ink ribbon 102 to be wound up to a position where the head-up sensor (optical sensor) 93 attached to the head arm 28 detects the mark 108.
When the mark 108 is detected, the color ink ribbon 102 is stopped.

When the paper 202 is inserted,
The presence of the paper 202 is first detected by the edge sensor 32, the front end of the paper 202 is positioned by the positioning member 73, and then the printing device is moved to a position where the rear edge is detected by the edge sensor 32. It is brought in.

When the trailing edge of the paper and the mark 108 of the color ink ribbon 102 are detected, the thermal head 19 carries the color ink ribbon 102 together with the print position shown by (D) in FIG. That is, the platen roller 66 is positioned so as to sandwich the ink ribbon 102 and the paper 202, and printing is performed. When printing is performed, the color ink ribbon 102 described above is used.
And the paper 202 are both the platen roller 6
6 and the thermal head 19 from the discharge hole 27
The paper is conveyed in the direction of being pulled out to the side by a distance corresponding to the size of the image to be printed.

When the printing of the first color (Y) is completed, the signal processing circuit 14 returns the paper 202 to the printing start position, that is, the position where the trailing edge is detected by the edge sensor 32. , The above ink ribbon 1
Wind up 02 to the start position of the second color (C). At this time, the thermal head 19 is in the standby position shown by (C) in FIG. The cueing sensor 93 detects the mark 109 between the first color (Y) and the second color (C).
8D, the thermal head 19 is set to the printing device shown in FIG. 8D, and the second color (C) is set.
Print.

When the printing of the second color (C) is completed, the signal processing circuit 14 returns the paper 202 to the printing start position, that is, the position where the trailing edge is detected by the edge sensor 32. , The above ink ribbon 1
Wind up 02 to the starting position for the third color (M). At this time, the thermal head 19 is in the standby position shown by (C) in FIG. The cueing sensor 93 causes the mark 109 between the second color (C) and the third color (M).
8 is detected, the thermal head 19 is set to the printing device indicated by (D) in FIG. 8, and the third color (M)
Print.

When the printing of the third color (M) is completed,
The signal processing circuit 14 causes the paper 202 to be ejected and causes the color ink ribbon 102 to move to the next first
Send to the start position of color (Y). Then, the thermal head 19 is returned to the initial position shown by (A) in FIG. At this time, the rewind reel shaft 34 is rotated, and the slack of the color ink ribbon 102 is removed.

When monochrome printing is performed in this printing apparatus, the monochrome ink ribbon cassette 103 shown in FIG. 23 is mounted. The fact that the monochrome ink ribbon cassette 103 has been mounted is determined by the signal processing circuit 14 via the pressing switch 21.

In the initial state, the head arms 28, 28 are rotated upward, and the thermal head 19 is separated from the monochrome ink ribbon 104 shown by (A) in FIG. In position. Then, when the print start button 4 is pressed and the paper 202 is inserted, printing is started. That is, first, the presence of the inserted sheet 202 is detected by the edge sensor 32, and the front end portion is positioned by the positioning member 73, and then the rear edge is detected by the edge sensor 32. Until then, it is carried into this printing apparatus. Then, the thermal head 19 is brought to the print position shown by (D) in FIG. 8 by the rotation of the head arms 28, 28, and prints. When printing is performed, the monochrome ink ribbon 104 is used.
And the paper 202 are both the platen roller 6
6 and the thermal head 19 from the discharge hole 27
The paper is conveyed in the direction of being pulled out to the side by a distance corresponding to the size of the image to be printed.

When the printing is completed, the signal processing circuit 14
Ejects the paper 202. Then, the thermal head 19 is returned to the initial position shown by (A) in FIG. At this time, the rewind reel shaft 34 is rotated, and the slack of the monochrome ink ribbon 104 is removed.

In the color ink ribbon 102, the ribbon end is black. On the other hand, in the monochrome ink ribbon 104, the ribbon end is transparent. Each of these ribbon ends is detected by the cueing sensor 93 and judged by the signal processing circuit 14. Whether to judge black as ribbon end or transparent as ribbon end,
The signal processing circuit 14 determines whether the color or monochrome ribbon cassette 101 or 103 is mounted according to the operation state of the pressing switch 21. Further, when the ribbon end is detected, the signal processing circuit 14 is connected to the signal processing circuit 14 and arranged so as to face the outer side of the outer casing 1 as shown in FIGS. 1 and 2. The ribbon end display lamp 99 is turned on.

That is, the signal processing circuit 14 shown in FIG.
As shown in the flowchart of FIG. 4, when the operation is started in step st1, the process proceeds to the subroutine SR1 and the above-described printing operation is executed (printing execution). And
When the printing operation for one sheet is completed, the signal processing circuit 14 proceeds to the subroutine SR2.

In this subroutine SR2, FIG.
As shown in the flowchart of FIG. 5, in step st6, it is determined whether the ink ribbon accommodated in the mounted ribbon cassette is the color ink ribbon 102. If the ink ribbon accommodated in the mounted ribbon cassette is the color ink ribbon 102, the process proceeds to step st7. If the ink ribbon accommodated in the ribbon cassette is not the color ink ribbon 102, the process proceeds to step st8. . In step st7,
When the signal processing circuit 14 determines that the ink ribbon in the vicinity of the thermal head 19 is in a state of substantially blocking light (black) according to the output signal of the head-out sensor 93, the ink ribbon is detected. It is set so as to determine that it is the end of the process, and the process proceeds to step st9 and returns. Further, in step st8, the signal processing circuit 14 is in a state (clear) in which the ink ribbon in the vicinity of the thermal head 19 transmits almost all light in accordance with the output signal of the head search sensor 93. When it is determined, it is set to determine that it is the end of the ink ribbon, and the process proceeds to step st9 and returns.

Upon returning from the subroutine SR2, the signal processing circuit 14 proceeds to step st2,
It is determined whether or not the ink ribbon of the mounted ribbon cassette reaches the end (ribbon end). If the ink ribbon of the ribbon cassette has reached the end, the process proceeds to step st3, and if the ink ribbon of the ribbon cassette has not reached the end, the process returns to the subroutine SR1.
In step st3, the ribbon end display lamp 99 is turned on to display that the ink ribbon has reached the end (end display), and the process proceeds to step st4.
In step st4, the printing operation is stopped, the process proceeds to step st5, and the program ends.

[0076]

As described above, in the printing apparatus according to the present invention, when the control means is one in which the mounted ribbon cassette accommodates a color ink ribbon, the ink ribbon in the vicinity of the thermal head is substantially removed. When the light is blocked, it is determined that the end of the ink ribbon is reached, and when the attached ribbon cassette accommodates a monochrome ink ribbon, the ink ribbon near the thermal head is almost It is determined that the end of the ink ribbon is reached when all the light is transmitted.

Therefore, in this printing apparatus, the end of the ink ribbon can be accurately determined regardless of whether the color or monochrome ink ribbon is used.

That is, the present invention is small and simple, and
It is possible to provide a printing apparatus that can print a good image while the printing operation is easy.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a printing apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of the printing apparatus.

FIG. 3 is a perspective view of a main part showing the configuration of the printing apparatus.

FIG. 4 is an exploded perspective view showing a configuration of the printing apparatus.

FIG. 5 is an exploded perspective view showing a configuration of a head moving mechanism of the printing apparatus.

FIG. 6 is a vertical cross-sectional view showing a state of printing in the printing apparatus.

FIG. 7 is a perspective view showing a paper supply portion of the printing apparatus.

FIG. 8 is a side view showing a positional relationship between a sheet and a thermal head in the printing apparatus.

FIG. 9 is a side view showing a configuration of a reel shaft rotating mechanism of the printing apparatus.

FIG. 10 is a side view showing a configuration of a rotating arm of the reel shaft rotating mechanism.

FIG. 11 is a side view showing a configuration of a stopper member of the reel shaft rotating mechanism.

FIG. 12 is a side view showing an operating state of the stopper member.

FIG. 13 is a front view showing the configuration of the stopper member.

FIG. 14 is a side view showing a configuration of a positioning member of the printing apparatus.

FIG. 15 is a side view showing a state where the positioning member is moved and operated.

FIG. 16 is a side view showing a configuration of a feed roller of the printing apparatus.

FIG. 17 is a side view showing a state in which a pinch roller is pressed against the feed roller.

FIG. 18 is a plan view showing a configuration of a pressing switch of the printing apparatus, in a state where a color ink ribbon cassette is mounted.

FIG. 19 is a plan view showing a configuration of a press switch of the printing apparatus, in a state where a monochrome ink ribbon cassette is mounted.

FIG. 20 is a plan view showing the configuration of a color ink ribbon.

FIG. 21 is a perspective view showing a mechanism for rotating a feed roller of the printing apparatus.

FIG. 22 is a perspective view showing a configuration of a color ink ribbon cassette.

FIG. 23 is a perspective view showing the configuration of a monochrome ink ribbon cassette.

FIG. 24 is a flowchart showing the operation of the printing apparatus, showing a main routine for executing the printing operation.

FIG. 25 is a flowchart showing the operation of the image printing apparatus, showing a subroutine SR2 for setting conditions for the ribbon end.

[Explanation of symbols]

 19: Thermal head 25: Guide plate 33: Winding reel shaft 34:・ ・ ・ ・ ・ ・ ・ Rewinding reel shaft 35 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Reel motor 43 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Brake arm 63 ・ ・ ・ ・ ・ ・・ ・ ・ Cassette holder 64 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Feed roller 65 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Pinch roller 66 ・ ・ ・ ・ ・・ Platen roller 67 ・ ・ ・ ・ ・ ・ ・ ・ ・ Restoring plate 101 ・ ・ ・ ・ ・ ・ ・ ・ Color ink ribbon cassette 102 ・ ・ ・ ・ ・ ・ ・ ・ ・ Color ink ribbon 103: Monochrome ink ribbon cassette 104: Monochrome ink ribbon 01 ............ image monitor 202 ............ paper

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

A plurality of types of the above-mentioned original image screens are prepared, and by using wet inks of different colors according to the images formed on these original image screens, a plurality of original image screens are overlaid and printed on one sheet of paper to form a color image. Printing can also be performed.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The printer block 20 is housed in the rear portion of the outer casing 1, as shown in FIG. A color ink ribbon cassette 101 shown in FIG. 22 or a monochrome ink ribbon cassette 103 shown in FIG. 23 is mounted on the printer block 20.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

The color ink ribbon 102 is shown in FIG.
As shown in FIG. 3, ink of each color of Y (yellow), M (magenta), and C (cyan) is applied to a film base made of a synthetic resin material to be formed. In this color ink ribbon 102, Y (yellow), M (magenta), and C (cyan) regions are alternately formed.
Marks 108 and 109 for cueing are provided between the areas. The mark 108 before Y is for each color Y, M,
It indicates that the start position of a set of printing regions made of C is longer than the other marks 109.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0041

[Correction method] Change

[Correction content]

Therefore, the ribbon reel engaged with the rewinding reel shaft 34 becomes the ink ribbons 102, 10.
When 4 is rotated in the rewinding direction, the ink ribbons 102 and 104 are not rewound by the ribbon reel, and the ink between the ribbon reel and the ribbon reel engaged with the winding reel shaft 33 is rewound. Ribbon 1
The tension of 02, 104 is increased. The reel shafts 33, 34 are supported by the support shaft via a clutch member and generate a constant load when rotated by an external force.
The tension of 02 and 104 is maintained.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

A head index sensor 93 and an end sensor 97, which are light transmittance sensors for detecting the marks 108 and 109 of the color ink ribbon 102, are attached to the head arm 28. These head sensors 9
The output signals of 3 and the end sensor 97 are supplied to the signal processing circuit 14 as shown in FIG. The signal processing circuit 14 determines the light transmittance of the ink ribbon in the vicinity of the thermal head 19 according to the output signal of the head-up sensor 93.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction content]

When the paper 202 is inserted,
The presence of the paper 202 is first detected by the edge sensor 32, the front end of the paper 202 is positioned by the positioning member 73, and then the printing device is moved to a position where the rear edge is detected by the edge sensor 32. It is brought in.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0064

[Correction method] Change

[Correction content]

In the initial state, the head arms 28, 28 are rotated upward, and the thermal head 19 is separated from the color ink ribbon 102 shown in FIG. 8A. In position. And
When the print start button 4 is pressed, the thermal head 19 is rotated by the rotation of the head arms 28, 28.
The mark detection position is shown by (C) in FIG. In addition,
At this time, if the presence of the paper 202 is not detected, the operation is not performed even if the printing start button 4 is pressed. When the operation is performed, the thermal head 19
Contacts the color ink ribbon 102. Here, the signal processing circuit 14 causes the color ink ribbon 102 to be wound up to a position where the head-on sensor (optical sensor) 93 attached to the head arm 28 detects the mark 108. When the mark 108 is detected, the color ink ribbon 102 is stopped.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0066

[Correction method] Change

[Correction content]

When the printing of the first color (Y) is completed, the signal processing circuit 14 returns the paper 202 to the printing start position, that is, the position where the trailing edge is detected by the edge sensor 32. At this time, the thermal head 19 is in the standby position shown by (B) in FIG. In addition, the signal processing circuit 14 includes the ink ribbon 102.
To the start position of the second color (M). At this time, the thermal head 19 is at the mark detection position shown by (C) in FIG. The head start sensor 93 is the first
The mark 10 between the color (Y) of the second color and the color (M) of the second color.
When 9 is detected, the thermal head 19 is set to the printing device indicated by (D) in FIG. 8, and the second color (M) is set.
Print.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0067

[Correction method] Change

[Correction content]

When the printing of the second color (M) is finished, the signal processing circuit 14 returns the paper 202 to the printing start position, that is, the position where the trailing edge is detected by the edge sensor 32. At this time, the thermal head 19 is in the standby position shown by (B) in FIG. In addition, the signal processing circuit 14 includes the ink ribbon 102.
To the start position of the third color (C). At this time, the thermal head 19 is at the mark detection position shown by (C) in FIG. The head start sensor 93 is the second
The mark 10 between the color (M) and the third color (C).
When 9 is detected, the thermal head 19 is set to the printing device shown by (D) in FIG. 8, and the third color (C) is set.
Print.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0068

[Correction method] Change

[Correction content]

When the printing of the third color (C) is completed,
The signal processing circuit 14 causes the paper 202 to be ejected and causes the color ink ribbon 102 to move to the next first
Send to the start position of color (Y). Then, the thermal head 19 is returned to the initial position shown by (A) in FIG. At this time, the rewind reel shaft 34 is rotated, and the slack of the color ink ribbon 102 is removed.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Name of item to be corrected] 0072

[Correction method] Change

[Correction content]

In the color ink ribbon 102, the ribbon end is black. On the other hand, in the monochrome ink ribbon 104, the ribbon end is transparent. Each of these ribbon ends is detected by the end sensor 97 and judged by the signal processing circuit 14. Whether to judge black as ribbon end or transparent as ribbon end,
The signal processing circuit 14 determines whether the color or monochrome ribbon cassette 101 or 103 is mounted according to the operation state of the pressing switch 21. Further, when the ribbon end is detected, the signal processing circuit 14 is connected to the signal processing circuit 14 and arranged so as to face the outer side of the outer casing 1 as shown in FIGS. 1 and 2. The ribbon end display lamp 99 is turned on.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0074

[Correction method] Change

[Correction content]

In this subroutine SR2, FIG.
As shown in the flowchart of FIG. 5, in step st6, it is determined whether the ink ribbon accommodated in the mounted ribbon cassette is the color ink ribbon 102. If the ink ribbon accommodated in the mounted ribbon cassette is the color ink ribbon 102, the process proceeds to step st7. If the ink ribbon accommodated in the ribbon cassette is not the color ink ribbon 102, the process proceeds to step st8. . In step st7,
When the signal processing circuit 14 determines that the ink ribbon in the vicinity of the thermal head 19 is in a state of substantially blocking light (black) according to the output signal of the end sensor 97, the signal processing circuit 14 outputs the ink ribbon. It is set so as to determine that it is the end, and the process proceeds to step st9 and returns. Further, in step st8, the signal processing circuit 14 determines that the ink ribbon in the vicinity of the thermal head 19 is in a state of transmitting almost all light (clear) according to the output signal of the end sensor 97. When it is done, it is set to judge that it is the end of the ink ribbon, and the process proceeds to step st9 and returns.

[Procedure Amendment 14]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 15]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure Amendment 16]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 20

[Correction method] Change

[Correction content]

FIG. 20

[Procedure Amendment 17]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 23

[Correction method] Change

[Correction content]

FIG. 23

Claims (1)

[Claims] 1. A printing apparatus for printing by printing an ink of an ink ribbon onto a printing material by pressing the ink ribbon onto the printing material with a thermal head, the ribbon cassette containing the ink ribbon. A plurality of pressing switches for identification corresponding to one or a plurality of ribbon type identification protrusions provided, and a light transmittance sensor for detecting the light transmittance of the ink ribbon housed in the ribbon cassette near the thermal head. According to the pressing operation state of each pressing switch, the ribbon cassette is mounted and the type of the mounted ribbon cassette is determined, and the vicinity of the thermal head is detected based on the output signal of the light transmittance sensor. And a control means for determining the light transmittance of the ink ribbon in the ink ribbon. When the ink ribbon accommodates a color ink ribbon, when the ink ribbon near the thermal head is in a state of substantially blocking light, the ink ribbon is judged to be the end of the ink ribbon, and the ink ribbon is mounted. If the ribbon cassette you are using contains a monochrome ink ribbon,
A printing apparatus for determining that the end of an ink ribbon near the thermal head is in a state where almost all light is transmitted.