JPH048406Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical device using a liquid crystal, and particularly to a liquid crystal optical device that performs optical writing using a liquid crystal that opens and closes in response to an information signal as a shutter.

[Prior art and its problems]

Conventionally, a liquid crystal shutter unit uses a liquid crystal as a shutter, and is constructed by arranging one or more rows of microshutters that open and close according to information signals.The light from a light source is modulated, and this modulated light is sent to a photoconductor using an imaging lens. There are known devices that perform optical writing by forming an image on the surface. In such an optical recording device, in order to open and close the liquid crystal shutter quickly and efficiently, it is required to maintain the temperature within a suitable temperature range called a stable driving temperature. For this reason, a heater is attached to heat the liquid crystal shutter, and the temperature on the surface of the liquid crystal shutter is detected to control the temperature. In this case, the space around the liquid crystal shutter unit is usually sealed against dust with a shielding material to prevent dirt, dust, toner, etc. from entering.

In a conventional optical recording device with such a configuration,
Although the space around the liquid crystal shutter unit mentioned above is sealed against dust, it is not sealed to the extent that there is no communication with the outside air. Therefore, under conditions of high humidity, external air containing a large amount of moisture flows in, and dew condensation is likely to occur on members whose temperature is lower than the ambient temperature.

In particular, when the main power is turned on after starting use, the temperature of the liquid crystal shutter increases as the heater for heating the liquid crystal shutter unit is turned on, and the atmospheric temperature in the above-mentioned space also rises. Since the temperature of the imaging lens, which is spaced apart from the liquid crystal shutter through the space, remains low, dew condensation occurs on the surface of the imaging lens. As a result, the condensation that formed obstructed the progress of the light, and even after the recording operation started, the amount of light from the light source was insufficient due to condensation for the first few sheets, resulting in image defects such as blurring of the image. . Furthermore, the polarizing plate provided near the liquid crystal shutter unit is usually susceptible to deterioration due to moisture, and therefore, the presence of moisture shortens the life of the entire liquid crystal optical device.

[Purpose of invention]

In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a liquid crystal optical device that can always exhibit stable optical effects without causing dew condensation on internal optical elements regardless of changes in environmental temperature. .

[Key points of the idea]

In order to achieve the above object, the present invention includes a light source,
A liquid crystal light shutter including a large number of microshutters that selectively transmit light from the light source, a heating means for heating the liquid crystal light shutter, and an image of the transmitted light of the liquid crystal light shutter on the surface of a photoreceptor. In a liquid crystal shutter printer having an imaging lens and performing optical writing on the surface of the photoreceptor, a heat transfer member is provided for thermally coupling the heating means and the imaging lens, and the heating means It is characterized in that the imaging lens is heated via the heat transfer member.

[Example of idea]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic diagram of a recording apparatus using the optical writing head H of the present invention.

The recording device is an optical writing device as a liquid crystal optical device consisting of a photoreceptor drum 1, a charger 2 for uniformly charging the surface of the photoreceptor drum 1 by corona discharge, a fluorescent lamp 3, a liquid crystal shutter unit 4, an imaging lens 5, etc. A developing device 6 uses toner to visualize the electrostatic latent image formed by the optical writing head H on the photosensitive drum 1 in accordance with recorded information, and the toner-developed image on the photosensitive drum is transferred to a sheet of paper. 8, a cleaner 9 that removes untransferred toner from the surface of the photosensitive drum, and the like.

FIG. 1 is an enlarged sectional view of a main part of an optical writing head H used in a recording apparatus having such a configuration. In the figure, a lamp housing 10 having a fluorescent lamp 3 for a light source therein is provided with an opening 10a at the center of its lower end, and the opening 10a is covered with a dustproof glass 11 that allows only light to pass through.
A mounting base 12 for holding a liquid crystal shutter unit 4, an imaging lens 5, etc. is fixed to the lower end of the lamp housing 10. The liquid crystal shutter unit 4 is constructed by arranging a large number of microshutters (not shown) in one row or in a plurality of rows, and opens and closes them individually in response to drive signals from a control circuit (not shown). Further, on the incident side and the output side of the liquid crystal shutter unit 4, a pair of polarizing films 4a, each made of a uniaxially stretched polyvinyl alcohol film and iodine molecules arranged in a fixed direction, are provided.
4a is attached. Further, on the output side of the liquid crystal shutter unit 4, a heater 13 for heating the liquid crystal shutter is provided at a location that does not interfere with the optical path through a polarizing film 4a. This is to maintain the liquid crystal shutter unit 4 always within a suitable temperature range and to ensure high-speed opening and closing operations in response to recording signals. Therefore, the energization is controlled by a control circuit (not shown) so that the temperature is maintained within a constant temperature range.

Thus, between the liquid crystal shutter unit 4 and the inner wall surfaces on both sides of the optical path of the mounting base 12, a heater 13 and one end of each of a pair of heat transfer plates 14, which are heat transfer members, are interposed. The other end of the heat exchanger plate 14 is interposed between the imaging lens 5 and the inner wall surface of the mounting base 12 . At each contact surface between each heat exchanger plate 14, heater 13, and imaging lens 5,
For example, silicone grease is applied to improve thermal conductivity between each contact surface. Heat transfer plate 1
4 is preferably made of copper or a phosphor bronze plate, which has excellent thermal conductivity, but aluminum or the like can also be used. Also, regarding the thickness, if it is less than 0.1 mm, the heat transfer function is insufficient, and if it is more than 0.5 mm, the heat capacity is large, and it takes too much time to reach the specified temperature after the heater starts energizing. There are drawbacks. Therefore, 0.1 mm or more, 0.5
Materials with a thickness of mm or less are desirable. Incidentally, a dustproof glass 15 is attached below the imaging lens 5 constituting the lower end of the optical writing head H.

Optical writing head H configured as described above
When the main power source is turned on when starting to use the recording apparatus, the heater 13 starts to be energized.
Then, the heater 13 heats the liquid crystal shutter unit 4 that comes into contact with it, and also heats the heat exchanger plate 14. The heated heat exchanger plate 14 is connected to the imaging lens 5
The incident side end 5a of the imaging lens 5 is heated, and the imaging lens 5
The space S surrounded by the liquid crystal shutter unit 4 and the heat transfer plate 4 is also heated. However, since the temperature of the incident-side end surface 5a of the imaging lens 5 that is in direct contact with the heat exchanger plate 14 rises at a rate equal to or higher than the rise in the air temperature in the space S, the inconvenience of condensation occurring is reliably avoided. .

In addition, in the above embodiment, the pair of heat exchanger plates 14, 1
4 is disposed around the imaging lens 5, but the present invention is not limited to this, and the heat exchanger plate may be formed into a cylindrical shape with a flange, and the emission hole 1 of the mounting base 12 may be
It may be configured to be inserted into 2a. In the case of such a configuration, when assembling, simply attach the exit hole 1.
Since it is only necessary to insert it into 2a, work efficiency can be improved. Furthermore, if a heat insulating film or the like is interposed between the heat exchanger plate 14 and the inner surface of the emission hole 12a of the mounting base 12, the heat from the heater 13 and the heat exchanger plate 14 can be effectively utilized, and the imaging lens 5 can be Heating time can be further shortened.

As described above, in the optical writing head H of the present invention, since the heater that heats the liquid crystal shutter unit 4 also serves to heat the imaging lens, the structure is simple and the number of parts can be reduced.

[Effect of idea]

As explained above, according to the liquid crystal optical device of the present invention, since a heat transfer member is installed between the heater and the imaging lens, which is an optical element, It is possible to prevent dew condensation on the imaging lens, prevent image defects such as blurring due to insufficient light amount due to dew condensation on the imaging lens, and improve image quality.

Furthermore, since the heater that heats the liquid crystal member also serves to heat the optical element, the structure is simple and an inexpensive liquid crystal optical device can be provided. Furthermore, since the heat transfer member itself will not be damaged, it can be constructed robustly.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of essential parts of an embodiment of the liquid crystal optical device of the present invention, and FIG. 2 is a schematic configuration diagram of a recording apparatus using the liquid crystal optical device of the present invention. H... Optical writing head, S... Space, 1... Photosensitive drum, 2... Charger, 3... Fluorescent lamp, 4...
...Liquid crystal shutter unit, 5...Imaging lens, 5
a...Incidence side end, 6...Developer, 7...Transfer device, 8...Paper, 9...Cleaner, 10...Lamp housing, 11, 15...Dust-proof glass, 12
...Mounting base, 13...Heater, 14...Heat transfer plate.

Claims (1)

[Claims for Utility Model Registration] A liquid crystal light shutter comprising a light source and a number of microshutters that selectively transmit light from the light source;
A liquid crystal shutter printer that performs optical writing on the surface of the photoreceptor, comprising a heating means for heating the liquid crystal light shutter and an imaging lens for forming an image of transmitted light of the liquid crystal light shutter on the surface of the photoreceptor. A liquid crystal shirt, characterized in that a heat transfer member is provided for thermally coupling the heating means and the imaging lens, and the heating means heats the imaging lens via the heat transfer member. Tap printer.