JP2745631B2 - Exposure control device in image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine for forming an image using a photosensitive recording medium (see Japanese Patent Application Laid-Open No. 58-88739). The present invention also relates to an exposure control device for an image recording apparatus having a sub-exposure device for irradiating light having no document image information onto the medium.

[Prior Art] Photosensitive pressure-sensitive paper capable of forming a color image (US Pat.
No. 209), in order to improve the gradation of an image, a uniform white light that is not image information is exposed separately from a main exposure device that irradiates a document image onto a photosensitive recording medium. It is known to include a sub-exposure device that irradiates a fixed amount of pressure-sensitive paper.

[Problems to be Solved by the Invention] However, in the above apparatus, the sub-exposure amount for optimally performing the sub-exposure is about 10 to 20% of the main exposure amount for exposing an image. When the image forming apparatus uses the line exposure method and adjusts the exposure amount of the main exposure by increasing or decreasing the speed of the photosensitive paper to obtain the optimum exposure, if the light intensity of the sub-exposure lamp is constant, the speed of the photosensitive paper Changes, the sub-exposure amount per unit area of the photosensitive paper changes accordingly. In such an apparatus, the transport speed of the photosensitive paper is originally increased or decreased every time the transport speed of the photosensitive paper is changed, even though the main exposure is performed to a predetermined amount. The ratio of the sub-exposure changes, which causes inconvenience such as impairing the improvement of the gradation of the image.

Further, even when the speed of conveying the photosensitive paper is increased or decreased in order to increase or decrease the copy magnification, the same inconvenience occurs if the amount of sub-exposure is kept constant.

The present invention solves the above-described problems, and is mainly intended to obtain the optimum exposure defined by the characteristics of the photosensitive paper and to change the copy magnification when the transport speed of the photosensitive paper is increased or decreased. Provided is an exposure control device for an image recording apparatus that can maintain a constant ratio of sub-exposure to main exposure even when the exposure amount of exposure changes, and can always maintain good gradation of an image. With the goal.

Means for Solving the Problems In order to achieve the above object, the present invention provides a main exposure apparatus that irradiates light based on image information onto a photosensitive recording medium, and a method that emits light without image information on the photosensitive recording medium. An image recording apparatus comprising: a sub-exposure device that irradiates the image onto the photosensitive recording medium; and an image density changing device that changes a main exposure amount of the main exposure device on the photosensitive recording medium in accordance with an image forming density. And a sub-exposure amount changing means for increasing or decreasing the sub-exposure amount by the sub-exposure device when the image density is changed.

[Operation] According to the above configuration, when the main exposure amount by the main exposure device is changed according to the image forming density, the light amount of the sub-exposure is increased or decreased accordingly. Thus, the exposure amount of the sub-exposure can always be a desired constant ratio with respect to the exposure amount of the main exposure. In the following embodiment, the image density changing means corresponds to the copy magnification setting key 43 and the image density setting key 44, and the sub-exposure amount changing means corresponds to the control device 45 and the sub-exposure control circuit.

[Embodiment] FIG. 1 shows a schematic configuration of a photosensitive pressure-sensitive copying machine capable of full-color copying according to an embodiment of the present invention. The photosensitive paper composed of the microcapsule paper and the color developing paper used in the copying machine of the present embodiment has been proposed in Japanese Patent Application Laid-Open No. 58-88739, etc., and will not be described in detail here.

The photosensitive pressure-sensitive copier 1 is composed of a platen glass 2 and a platen cover 3 whose top part is movable in the left-right direction.
A desired original is set on the original platen glass 2 in a state of being face down. A light source (main exposure device) 4 using a halogen lamp extending in a direction orthogonal to the moving direction of the original platen glass 2 and a semi-cylindrical reflecting mirror arranged so as to surround the right upper portion of the copying machine 1 5 is provided and the platen glass 2
Light is irradiated linearly through a slit through hole provided on the upper surface of the fuselage. Therefore, the light emitted from the halogen lamp 4 sequentially irradiates the entire surface of the platen glass 2 from the left end to the right end by moving the platen glass 2 in the left-right direction. The light emitted from the light source passes through the transparent platen glass 2, is reflected by the original placed thereon, and the exposure of the original is scanned.

In order to use the light emitted from the halogen lamp 4 for illuminating the original, a reflector 6 is disposed on the left side of the light source, and reflects light that does not go directly to the original to use it again for illuminating the original. A fan 7 and a louver 8 for introducing air from the outside are provided on the right side of the halogen lamp 4, so that cooling air is applied to the platen glass 2.

Light emitted from the halogen lamp 4 and reflected from a document located on the document table glass 2 passes through the filter 9 and enters the lens 10. The filter 9 is for adjusting the color tone of the copied image, and controls the change of the light transmission characteristic according to the sensitivity characteristic of the microcapsule paper 11. The lens 10 is mounted on a lens mounting plate 12 to enable fine angle adjustment with respect to the optical path. The light condensed by the lens 10 is turned 180 ° by a pair of reflecting mirrors 13 and 13, and
14 An image is formed on the microcapsule paper 11 closely contacted below. The reflection mirrors 13, 13 are mounted on a mirror mounting plate 15, and fine adjustment of the mounting position of the mirror mounting plate 15 adjusts the adjustment focus of the optical path length.

On the other hand, the elongate microcapsule paper 11 is housed in a removable cartridge 17 disposed below the platen glass 2 in a state of being wound around a cartridge shaft 16, and one end of the microcapsule paper 11 has a large number of rollers. And a pressure developing device 18 to reach a winding shaft 19. That is, the microcapsule paper 11 coming out of the lower part of the cartridge 17 is guided by the feed roller 20, the Tyco roller 21, and the nip roller 21 ', and
, And is supplied to the pressure developing device 18. The microcapsule paper 11 that has passed through the pressure developing device 18 is guided by a peeling roller 22 and a meandering adjusting roller 23, and then is wound on a winding shaft 19. The unexposed microcapsule paper 11 after leaving the cartridge 17 is kept unexposed by the light-shielding cover 24.

Further, a control device 45 for controlling the entire copying machine, in particular, the conveyance speed of the microcapsule paper 11 and the light amount of the sub-exposure lamp 41 is provided. Hereinafter, the peripheral structure of the control device 45 will be described with reference to FIG. I will explain. The control device 45 is constituted by a microcomputer, and includes a copy magnification setting key 4 provided on an operation panel (not shown).
3.A setting signal from the image density setting key 44 etc. is input,
The control signal corresponding to this setting signal is sent to the motor speed control circuit 4.
6. Output to the sub-exposure control circuit (chopper) 48. A capsule paper transport motor 47 and a sub-exposure lamp 49 are connected to the control circuits 46 and 48, respectively. Since the capsule paper transport motor 47 drives the capsule paper feed roller 25, the transport speed of the microcapsule paper 11 is controlled to a predetermined speed by the roller 25, and is made to coincide with the moving speed of the platen glass 2. Therefore, a latent image of a predetermined line of the document is sequentially formed on the microcapsule paper 11 when passing through the exposure table 14.

Further, under the pressure developing device 18, there is provided a developing paper cassette 27 for accommodating a developing paper 26 of a cassette paper type. The developing paper 26 is taken out one by one by a half-moon-shaped feeding roller 28, and the developing paper is taken out. After the leading end is aligned by the roller 29 and the registration gate 30, the sheet is conveyed to the sheet carrying port of the pressure developing device 18.

Thus, the microcapsule paper 11 is
And the color developing paper 26 are supplied in close contact and integrated. The pressure developing device 18 includes a small-diameter roller 31 and a backup roller 32. The surface of the microcapsule on which the latent image of the microcapsule paper 11 is formed and the surface of the developer coated with the developer on the developer paper 26 are integrally sandwiched between the small-diameter roller 31 and the backup roller 32, and pressure is applied. Can be The unexposed microcapsules are destroyed by this pressure, and an image is formed on the color developing paper 26. The pressure developing device 18 and the heat fixing device 33 (described later) constitute processing means for forming an image.

The microcapsule paper 11 and the color developing paper 26 that have come out of the pressure developing device 18 are conveyed by a capsule paper feed roller 25, and the microcapsule paper 11 and the color developing paper 26 are separated by the peeling roller 22. The developed paper 26 is conveyed to the paper output tray 34 with the image side up after the color is promoted by the heat fixing device 33 to form an image. The heat fixing device 33 includes a heater 35 and a temperature sensor.
It comprises a hollow heat roller 37 having an inside 36 and a developing paper feed roller 38. The separated microcapsule paper 11 is wound around a winding shaft 19 via a meandering adjustment roller 23.

Further, below the pressure developing device 18, in the vicinity of the exposure table 14, and between the partition 42 in the machine, and downstream of the capsule paper 11 in the transport direction of the capsule paper 11, the sub-exposure is performed as if facing the exposure table 14. A lamp (sub-exposure device) 41 is provided. The sub-exposure lamp 41 is lit to increase the gradation of an image when a document is a photograph, for example, and emits white light having no image information. It is irradiated toward the microcapsule paper 11 (the upper side in FIG. 1) conveyed along. This sub-exposure lamp 41 can be
It is turned on, and when it is turned on, it is turned on and off in synchronization with the halogen lamp 4 as the main light source.

The sub-exposure lamp 41 can be configured using a plurality of optical fibers or the like.

 The operation of the above configuration will be described below.

Now, after the original platen cover 3 is opened and the original is placed on the original platen glass 2, when an exposure start switch (not shown) is pressed, the original platen glass 2 first moves rightward and Stops at the position where the left end of the is facing the light source. Thereafter, the document table glass 2 is moved leftward with the halogen lamp 4 turned on. The light emitted from the halogen lamp 4 is reflected by the original, reflected by the filter 9, the lens 10 and the pair of reflecting mirrors 13, 13 and then condensed on the microcapsule paper 11 located below the exposure table 14. Imaged. At this time, since the microcapsule paper 11 is moved leftward on the exposure table 14 at the same speed as the moving speed of the document table glass 2, an image on the document is formed on the microcapsule sheet 11 as a latent image. You.

Paper feed roller as the platen glass 2 moves to the left
The developed paper 26 is taken out from the developed paper cassette 27 by 28 and supplied to the pressure developing device 18 in a state where the developed paper 26 is superimposed on the exposed microcapsule paper 11.
The latent image on 11 is developed and transferred onto developed paper 26. Thereafter, the color-developed paper 26 is heat-fixed by the heat fixing device 33 and then discharged out of the copying machine 1. On the other hand, the microcapsule paper 11 that has passed through the pressure developing device 18 is sequentially wound around a winding shaft 19. When the right end of the platen glass 2 has moved to a position facing the light source, copying of the document is completed, and the halogen lamp 4 is turned off.

Next, the operation of the sub-exposure lamp 41 provided by providing the above-described exposure control device 45 will be described with reference to FIG.

The exposure control device 45 receives a setting signal from the copy magnification setting key 43 or the image density setting key 44 and outputs a predetermined motor speed control signal corresponding to the setting signal to the motor speed control circuit 46. The control circuit 46 is connected to a capsule paper transport motor 47, and the motor 47 drives the capsule paper transport roller 25. Therefore, the transport speed of the microcapsule paper 11 is controlled to a speed according to the set signal, and Exposure device 4
As a result, a latent image is formed with a predetermined exposure amount. The microcapsule paper 11 exposed by the main exposure device 4 is
When illuminated by the sub-exposure lamp 41 and subjected to sub-exposure to enhance the gradation of the image, the exposure control device 45 controls the amount of light of the sub-exposure lamp 41 by chopping through a sub-exposure control circuit (chopper) 48 Then, the duty is controlled so as to increase or decrease in proportion to the increase or decrease of the moving speed of the microcapsule paper 11. By performing such control, the sub-exposure amount per unit area of the microcapsule paper 11 can be kept constant irrespective of the moving speed of the microcapsule paper 11, and the gradation of the image of the paper 11 can be improved. Can be kept.

[Effects of the Invention] As described above, according to the present invention, independently of the main exposure device that irradiates light based on image information to a photosensitive recording medium, the image information is not provided in order to improve the gradation of an image. In an image forming apparatus such as a copying machine or a printer equipped with a sub-exposure device that irradiates light onto photosensitive pressure-sensitive paper, when the amount of main exposure is changed in order to change the density of a formed image, Since the amount of sub-exposure by the sub-exposure device is increased or decreased, the ratio of sub-exposure to main exposure is controlled to be always constant. As a result, the gradation of the image can be enhanced and maintained, and a desired high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an embodiment of an image recording apparatus equipped with an exposure control apparatus according to the present invention, and FIG. 2 is a block diagram showing a main part of the apparatus. 1 ... Photosensitive pressure-sensitive copying machine, 4 ... Halogen lamp (main exposure device), 11 ... Microcapsule paper, 41 ... Sub exposure lamp (sub exposure device), 43 ... Copy magnification setting key, 44 ...
Image density setting key, 45: control device, 46: motor speed control circuit, 47: capsule paper transport motor, 48: sub-exposure control circuit.

Claims (1)

(57) [Claims] 1. An image recording apparatus comprising: a main exposure device that irradiates light based on image information onto a photosensitive recording medium; and a sub-exposure device that irradiates light having no image information onto the photosensitive recording medium. An image density changing means for changing a main exposure amount of the photosensitive recording medium by the main exposure device in accordance with an image forming density; and when the image density is changed by the image density changing means, the sub-exposure corresponding thereto. An exposure control device for an image recording apparatus, comprising: a sub-exposure amount changing unit for increasing / decreasing a sub-exposure amount by the device.