JPH04317044A - Original illuminating device for copying machine - Google Patents

Abstract

PURPOSE:To provide an original illuminating device for copying machine where the eyes of an operator are protected from an irradiated light beam from a tubular light source in the case of copying an original in a state where a pressure plate is opened. CONSTITUTION:The output of a liquid crystal driver circuit 20 which drives the liquid crystal 18 of (n) picture elements provided in a transmission type liquid crystal display part 19 disposed on an optical path between a contact glass where the original is placed and the tubular light source every picture element is controlled by a liquid crystal driving range control means 22, and the liquid crystal 18 in the picture element area which is out of the size of the original is lighted out of the liquid crystal 18 of (n) picture elements of the display part 19 in accordance with the size of the original set by an original size setting means 21. By changing the deflecting direction of the liquid crystal 18 in the picture element area which is lighted, the irradiating light from the tubular light source does not leak from the area out of the size of the original even in the state where the pressure plate is opened.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document illumination device for a fixed document copying machine.

0002

2. Description of the Related Art In general, document illumination devices for copying machines are disclosed in Japanese Utility Model Application Publication No. 16153/1983 and Japanese Patent Application Laid-open No. 1983-16153.
It is disclosed in Japanese Patent Application Laid-open No. 28643 and Japanese Patent Application Laid-Open No. 60-42747. Among the copying machines equipped with such a document illumination device, the basic configuration of a conventional digital copying machine is shown in Figure 6.
This will be explained based on FIGS. That is, the digital copying machine includes, around the photoreceptor drum 1, an image reading section 3 that reads information on the document 2, and a writing section 4 that writes the read information on the document 2 onto the photoreceptor drum 1. A developing section (not shown) that develops the image formed on the photosensitive drum 1, a transfer section (not shown) that transfers the developed image to copy paper, a fixing section (not shown) that fixes the image to the copy paper, and a copying section. A transport section (not shown) that transports the paper is sequentially arranged.

As shown in FIG. 6, the image reading section 3 is provided with a contact glass 5 on which the original 2 is placed. A pressure plate 6 that can be opened and closed and presses the original 2 is provided on the upper surface of the contact glass 5. Further, a fluorescent lamp 7 as a tubular light source is provided below the contact glass 5.
, mirrors 8, 9, and 10, and a scanner 11 that moves along the document table. The length of the fluorescent lamp 7 of this scanner 11 is set to the width of the maximum document size that can be copied by the copying machine. A CCD 12 as a photoelectric converter is disposed on the optical path of the reflected light from the original 2 via the scanner 11. A reading control circuit 13 equipped with an A/D converter is connected to the output side of the CCD 12. An image processing section 14 is connected to the output side of this reading control circuit 13.

As shown in FIG. 7, the writing section 4 includes an LD (LD) connected to the image processing section 14 of the image reading section 3.
aser Diode) 15 is provided. This L
Polygon mirror 16 and lens group 1 are placed on the optical path of the light of D15.
The photosensitive drum 1 is provided via 7.

In this configuration, an operator first places the original 2 on the contact glass 5 and closes the pressure plate 6 to press the original 2. Then, when copying is started, the scanner 11 scans along the contact glass 5. Along with this scanning, the light emitted from the fluorescent lamp 7 of the scanner 11 passes through the contact glass 5 and is reflected on the original 2, and then passes through mirrors 8, 9, and 10 to the CCD 1.
2. The reflected light from the original document 2 that is incident on the CCD 12 is converted into an electrical signal and input to the reading control circuit 13 , which converts it into a digital signal and inputting it to the image processing section 14 . The digital signal input to the image processing section 14 is processed and edited and sent to the L of the writing section 3.
Sent to D15. The digital signal sent to the LD 15 is converted into an optical signal again and emitted as a laser beam, which is reflected by the polygon mirror 16 and further transmitted to the lens group 17.
The light is corrected by , and then irradiated onto the photoreceptor drum 1 . Then, an electrostatic latent image corresponding to the characters, figures, etc. of the document 2 is formed on the photoreceptor drum 1.

[0006]

However, when attempting to copy a thick original 2 such as a book original 2a, the pressure plate 6 cannot be closed and must be copied with the pressure plate 6 open. Here, when copying a book original 2a smaller in size than the maximum size original 2 with the pressure plate 6 open, the length of the fluorescent lamp 7 is set to the width of the maximum original size that can be copied by the copying machine. Therefore, the fluorescent lamp 7 illuminates a range of the document 2 corresponding to the maximum document size that can be copied. As a result, as shown in FIG. 8, there is a problem in that the irradiated light from the fluorescent lamp 7 in an area outside the size of the document 2 passes through the contact glass 5 and leaks upward, entering the operator's eyes.

[0007]

[Means for Solving the Problem] In the invention as set forth in claim 1, a press plate which can be opened and closed and presses the original is provided on the upper surface of the contact glass on which the original is placed, and a pressure plate that can be opened and closed to press the original is provided below the contact glass. A transmissive liquid crystal display unit having n pixels of liquid crystal whose polarization direction changes depending on an applied voltage is disposed on the optical path between the contact glass and the tubular light source, and the n-pixel A liquid crystal driver circuit is provided for supplying an applied voltage that changes the deflection direction for each pixel of the liquid crystal, and an original size setting means is provided for setting the size of the original, and the size of the original set by the original size setting means is adjusted. Liquid crystal driving range control means is provided for controlling the output of the liquid crystal driver circuit for each pixel of the liquid crystal so that an applied voltage is supplied only to the pixel region of the liquid crystal that is out of alignment.

In the invention as claimed in claim 2, in the invention as claimed in claim 1, there is provided a pressure plate opening/closing detection means for detecting the open/closed state of the pressure plate, and when the closed state of the pressure plate is detected, the operation of the transmissive liquid crystal display section is controlled. A liquid crystal operation stop means is provided to stop the liquid crystal operation.

[0009]

[Operation] In the invention as set forth in claim 1, the size of the original placed on the contact glass is set by the original size setting means, and the output of the liquid crystal driver circuit is controlled to control the liquid crystal drive range according to the set original size. The applied voltage is controlled by means for each pixel of the liquid crystal of the transmissive liquid crystal display section, and the applied voltage is supplied to the liquid crystal of the pixel area outside the original size from among the n pixel liquid crystals of the transmissive liquid crystal display section, and the applied voltage is supplied. The polarization direction changes in the pixel area of the liquid crystal that has been removed, and the light in the optical path of the pixel area of the liquid crystal that is outside the size of the document between the contact glass and the tubular light source is blocked. The irradiated light will no longer leak.

In the invention as set forth in claim 2, the opening/closing state of the pressure plate is detected by the pressure plate opening/closing detection means, and the liquid crystal operation stopping means stops the operation of the transmissive liquid crystal display section only when the pressure plate is in the closed state. It becomes possible to operate the transmission type liquid crystal display section in accordance with the open/closed state of the pressure plate.

[0011]

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 to 4. In addition, conventional examples (see Figures 6 to 8)
The same reference numerals are used for the same parts as those explained in , and the explanation thereof will be omitted (the same applies to the following embodiments). First, FIGS. 1 and 2 show the main configuration of this embodiment. The scanner 11 is provided with a transmissive liquid crystal display section 19 that is disposed on the optical path between the contact glass 5 and the fluorescent lamp 7 and includes an n-pixel liquid crystal 18 whose deflection direction changes according to an applied voltage. In the transmissive liquid crystal display section 19, liquid crystals 18 divided into n pixels in the sub-scanning direction Y are arranged in a straight line along the main scanning direction X. Also,
A liquid crystal driver circuit 20 that supplies an applied voltage for changing the deflection direction of the n pixels of the liquid crystal 18 of the transmissive liquid crystal display section 19 is connected to each of the n pixels of the liquid crystal 18. A document size selection switch 21 is provided as document size setting means for setting the size of the document 2. The liquid crystal driver circuit 20 is configured to supply an applied voltage only to pixel areas of the liquid crystal 18 that are outside the size of the original 2 set by the original size selection switch 21.
A CPU 22 serving as a liquid crystal drive range control means for controlling the output of each pixel of the liquid crystal 18 is connected to the liquid crystal driver circuit 20. However, a thick book original 2a smaller in size than the maximum size copyable original 2 is placed on the top surface of the contact glass, and the pressure plate 6 is set in an open state.

In such a configuration, when the size of the book document 2a is selected by the document size selection switch 21, a signal matching the size of the book document 2a is sent from the CPU 22 to the liquid crystal driver circuit 20. An applied voltage is supplied to the transmissive liquid crystal display section 19 according to the size of the book original 2a, so that a front electrode signal F and a back electrode signal R are output for each pixel of the liquid crystal 18. That is, a pixel area of the liquid crystal 18 of the transmissive liquid crystal display section 19 that is outside the area of the book original 2a is lit according to the size of the book original 2a according to a command from the CPU 22. The deflection direction changes in the pixel area of the liquid crystal 18 that is turned on, and the irradiation light from the fluorescent lamp 7 is blocked. This results in
The irradiated light from the fluorescent lamp 7 does not leak to areas other than the size of the book document 2a. For example, using a 7-pixel liquid crystal 18,
When copying a 5 size book original 2a, when B5 size is selected by the original size selection switch 22,
A B5 size signal is sent to the liquid crystal driver circuit 20 via the CPU 22, and the liquid crystal 18 in the three pixel areas A of B5 size or larger is turned on, as shown by diagonal lines in FIG. This 3
The liquid crystal 18 in the pixel area A corresponds to the area of the transmissive liquid crystal display section 19 shown by diagonal lines in FIG.

[0013] Therefore, the maximum size document 2 that can be copied
When copying a smaller size book manuscript 2a,
By selecting the lit pixel area of the n-pixel liquid crystal 18 according to the size of the book original 2a, the irradiation light of the fluorescent lamp 7 in the area outside the size of the book original 2a is blocked, and the pressure plate 6 is in an open state. However, it is controlled so that the irradiated light from the fluorescent lamp 7 does not leak and directly enter the operator's eyes. Moreover, excess toner does not adhere to the photoreceptor drum 1, and toner consumption is reduced.

Next, a second embodiment of the present invention will be explained based on FIG. A pressure plate open/close detection circuit 23 serving as a pressure plate open/close detection means for detecting the open/close state of the pressure plate 6 is connected to the liquid crystal driver circuit 20 . Further, when the pressure plate open/close detection circuit 23 detects the closed state of the pressure plate 6,
Liquid crystal operation stopping means (not shown) is provided to control the output of the liquid crystal driver circuit 20 and stop the operation of the transmissive liquid crystal display section 19.

In such a configuration, the open/close state of the pressure plate 6 is detected by the pressure plate open/close detection circuit 23, and as a result,
If the pressure plate 6 is in the open state, the liquid crystal drive signal S is directly sent from the liquid crystal driver circuit 20 to the transmissive liquid crystal display section 19 to drive the liquid crystal 18, and if the pressure plate 6 is in the closed state, the liquid crystal operation stop means The liquid crystal drive signal S of the liquid crystal driver circuit 20 is cut off, and the liquid crystal 18 is not driven. Therefore, the transmission type liquid crystal display section 1
It becomes possible to control the driving and driven of 9.

In the embodiment described above, the transmission type liquid crystal display section 19 is used to control the irradiation light of the fluorescent lamp 7 in the main scanning direction X of the original document 2.
, the sub-scanning direction Y of the document 2 is determined using known technology.
By providing a sensor or the like to detect the trailing edge, the fluorescent lamp 7 is set to turn off immediately after the trailing edge of the document is irradiated.

[0017]

[Effects of the Invention] According to the invention as set forth in claim 1, an openable and closable pressure plate for pressing the original is provided on the upper surface of the contact glass on which the original is placed, and the pressure plate moves along the contact glass below the contact glass. A tubular light source is provided, and a transmissive liquid crystal display section including n pixels of liquid crystal whose polarization direction changes depending on an applied voltage is disposed on the optical path between the contact glass and the tubular light source, and A liquid crystal driver circuit is provided for supplying an applied voltage that changes the deflection direction for each pixel, and document size setting means is provided for setting the size of the document, and the liquid crystal display is configured such that the liquid crystal display does not exceed the size of the document set by the document size setting device. Liquid crystal drive range control means is provided for controlling the output of the liquid crystal driver circuit for each pixel of the liquid crystal so that an applied voltage is supplied only to the pixel region of The size is set, and the output of the liquid crystal driver circuit is controlled for each pixel of the liquid crystal by the liquid crystal drive range control means according to the set size of the original, and the size of the original is selected from among the n pixels of liquid crystal on the transmissive liquid crystal display section. An applied voltage is supplied to the liquid crystal in the pixel area that is outside the size of the original, and the deflection direction changes in the pixel area of the liquid crystal to which the applied voltage is applied, and the pixel area of the liquid crystal that is outside the size of the original between the contact glass and the tubular light source is When the light in the optical path is blocked and the original size is smaller than the maximum size that can be copied,
Even when the pressure plate is open, the irradiated light from the tubular light source can be prevented from leaking into the operator's eyes, and additionally, it is possible to prevent unnecessary consumption of toner.

The invention according to claim 2 is the invention according to claim 1, further comprising pressure plate open/close detection means for detecting the open/closed state of the pressure plate, and when the closed state of the pressure plate is detected, the transmission type liquid crystal display section operates. Since the liquid crystal operation stop means is provided, the open/closed state of the pressure plate is detected by the pressure plate open/close detection means, and the liquid crystal operation stop means stops the operation of the transmissive liquid crystal display section only when the pressure plate is in the closed state. This has the effect that the transmission type liquid crystal display section can be operated in accordance with the open/closed state of the pressure plate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a front view showing the configuration of an image reading section of the copying machine.

FIG. 3 is a plan view showing a lighting state of the liquid crystal of the transmissive liquid crystal display section.

FIG. 4 is a plan view showing a lighting state of the liquid crystal of the liquid crystal display unit for a document;

FIG. 5 is a block diagram showing a second embodiment of the invention.

FIG. 6 is a front view showing the configuration of an image reading section of a conventional digital copying machine.

FIG. 7 is a front view showing the configuration of a writing section of a conventional digital copying machine.

FIG. 8 is a perspective view showing a state in which light from the tubular light source leaks and enters the operator's eyes.

[Explanation of symbols]

2 Manuscript 5 Contact glass 7 Tubular light source 18 Liquid crystal 19 Transmissive liquid crystal display section 20 Liquid crystal driver circuit 21 Original size setting means 22 Liquid crystal drive range control means 23 Liquid crystal operation stop means

Claims (2)

[Claims] 1. A pressure plate that can be opened and closed to press the original is provided on the upper surface of the contact glass on which the original is placed, a tubular light source that moves along the contact glass is provided below the contact glass, and the contact glass and the tubular light source, a transmissive liquid crystal display unit having n pixels of liquid crystal whose polarization direction changes depending on an applied voltage is disposed, and an applied voltage is applied to change the polarization direction for each pixel of the liquid crystal of n pixels. A liquid crystal driver circuit for supplying voltage is provided, a document size setting means for setting the size of the document is provided, and the applied voltage is supplied only to pixel areas of the liquid crystal that are outside the size of the document set by the document size setting means. 1. A document illumination device for a copying machine, comprising: a liquid crystal drive range control means for controlling the output of the liquid crystal driver circuit for each pixel of the liquid crystal so as to control the output of the liquid crystal driver circuit for each pixel of the liquid crystal. 2. A pressure plate opening/closing detection means for detecting the open/closed state of the pressure plate is provided, and a liquid crystal operation stop means is provided for stopping the operation of the transmissive liquid crystal display section when the closed state of the pressure plate is detected. 2. A document illumination device for a copying machine according to claim 1.