JP2808589B2 - Optical writing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention guides light emitted from a light source to an optical shutter using a material having an electro-optical effect such as PLZT, and applies a drive voltage to the optical shutter. To drive the optical shutter,
By irradiating the light to be irradiated with the light transmitted through the optical shutter,
The present invention relates to an optical writing device that records image information on an irradiation target. [Background of the Invention] In an optical shutter using a material having an electro-optical effect such as PLZT, the optical shutter is usually passed through a polarizer only when an appropriate voltage is applied to electrodes provided on both sides thereof. The light incident on is polarized by 90 ° and transmitted through the analyzer. In such an optical shutter, the relationship between the voltage V applied to the optical shutter and the intensity of transmitted light I transmitted through the analyzer is shown on the horizontal axis, the applied voltage V to the optical shutter is passed on the vertical axis, and the analyzer is passed on the vertical axis. When the transmitted light intensity I is plotted, it is represented by a characteristic curve as shown in FIG. 1, and when a voltage for polarizing light by 90 °, that is, a half-wavelength voltage Vλ / 2 is applied to the optical shutter, the analyzer The intensity of transmitted light passing through is maximized. The present inventors have studied on using an optical shutter array in which a large number of optical shutters are arranged as a writing device such as an electrophotographic printer, utilizing the above-described characteristics of the optical shutter. First, in order to match the drive of the optical shutter array with the rotation speed of the photosensitive drum for forming an image, the present inventors apply the half-wavelength voltage at which the transmitted light intensity is maximized to the driven optical shutter element. Vλ / 2 was applied in a pulsed manner to expose the photosensitive member. However, when the photoreceptor is exposed in this way, at the beginning of driving of the optical shutter, the transmitted light intensity is weak, the photoreceptor cannot be sufficiently exposed, the contrast is poor, and the exposure is thereafter performed. It has been found that there is a problem that the image density becomes uneven between the two. On the other hand, to sufficiently expose the photoconductor from the beginning of driving,
When the pulse width of the drive voltage applied to the optical shutter is increased, the system speed of a printer or the like is remarkably reduced, and high-speed processing cannot be performed. Therefore, the present inventors applied a half-wavelength voltage Vλ to the optical shutter.
In order to examine the characteristics of the transmitted light intensity when a voltage of 1/2 is applied, as shown in FIG.
The time-dependent changes in the transmitted light intensity from the optical shutter when a DC voltage of λ / 2 was applied and when a pulse voltage of a half-wavelength voltage Vλ / 2 was applied as shown in FIG. 3 were examined. As a result, as shown in these figures, when the DC voltage of the half-wavelength voltage Vλ / 2 or the pulse voltage is applied to the optical shutter, the rise of the transmitted light intensity is poor and the transmitted light intensity is not stable until it is stabilized. It took several hundred milliseconds. The present invention has been made in view of such circumstances, and drives the optical shutter so that the transmitted light intensity from the optical shutter is stabilized. It is an object of the present invention to irradiate an object to be irradiated with light having a stable transmitted light intensity so that stable writing can be performed and that image density does not become uneven. [Means for Solving the Problems] In the optical writing apparatus according to the present invention, in order to solve the above-described problems, light emitted from a light source is applied to an optical shutter made of a material having an electro-optical effect. In an optical writing device for controlling the transmission of light by this optical shutter and recording image information on an irradiation object, a mechanical shutter is provided in an optical path between the light source and the optical shutter, and the optical shutter is provided. Drive control means for applying a stabilizing voltage to the optical shutter to stabilize the intensity of light transmitted through the optical shutter before applying a driving voltage to the optical shutter to record image information on the object; While the stabilizing voltage is being applied, the above mechanical shutter is closed to block light from the light source, while the mechanical shutter is being applied while the driving voltage is being applied to the optical shutter. Shutter control means for opening the shutter to guide light from the light source to the optical shutter, the shutter control means including a light receiving element for receiving light transmitted through the optical shutter, and an output of the light receiving element. The mechanical shutter is opened and closed based on the above. In the optical writing device according to the present invention,
Before the driving voltage is applied to the optical shutter and image information is recorded on the illuminated object as described above, the driving control means applies a stabilizing voltage to the optical shutter and the intensity of transmitted light from the optical shutter rises. After the stabilization, a drive voltage is applied to the optical shutter to drive the optical shutter, so that the object to be irradiated can be stably irradiated with high transmitted light intensity through the optical shutter to which the drive voltage is applied. Become. Also, while the stabilizing voltage is applied to the optical shutter as described above, the mechanical shutter is closed by the shutter control means to block light from the light source, and the transmitted light intensity from the optical shutter rises to stabilize. Until the light emitted from the light source is transmitted through the optical shutter so as not to irradiate the illuminated object such as the photosensitive member, the illuminated object is not unnecessarily irradiated with the light. It is also possible to suppress variations in sensitivity and deterioration of the irradiation target. Further, as in the optical writing device according to the present invention, a light receiving element for receiving light transmitted through the optical shutter is provided in the shutter control means, and the mechanical shutter is opened and closed based on the output of the light receiving element. The opening and closing of the mechanical shutter by the control means can be performed easily and appropriately, and the light from the light source is reliably shut off by the mechanical shutter until the intensity of the transmitted light from the optical shutter rises sufficiently and stabilizes. The object to be irradiated is always illuminated with light having a stable and high transmitted light intensity through the optical shutter to which the voltage is applied. Embodiment An embodiment of the present invention will be specifically described below with reference to the accompanying drawings. (Embodiment 1) In this embodiment, as shown in FIGS. 4 and 5, an optical shutter array (10) in which a large number of optical shutters (1) are arranged is used as a writing device of an electrophotographic printer. The case will be described as an example. In the example shown in FIG. 4, a fluorescent lamp (11) having a high lighting speed is used as a light source, light from the fluorescent lamp (11) is condensed by a rod lens (12), and the light is condensed by a polarizer (13). Through the optical shutter array (10). Then, the driving circuit (14) for driving the optical shutter array (10), by applying a driving voltage V ₂ to the appropriate optical shutter (1), to polarize the light irradiated to the optical shutter (1) search The photons (15) are passed through, and this light is condensed by a selfoc lens array (16) and irradiated onto a charged photoconductor (17) to be recorded as image information. Here, in those in this embodiment, when driving the optical shutter (1), as shown in FIG. 6 and FIG. 7, as a stabilizing voltages V ₁ to the optical shutter (1), half-wave voltage Vλ After applying a DC voltage or a pulse voltage of / 2 to stabilize the transmitted light intensity of the optical shutter (1), the fluorescent lamp (11) is turned on by the controller (18) and the driving circuit (14) the half-wave voltage Vlambda / 2 of the pulse voltage is applied as a drive voltage V ₂ more optical shutter (1),
The optical shutter (1) is driven. Further, in those in this embodiment, by applying a stabilized voltage V _1, since the transmitted light intensity of the light shutter (1) to verify that it has stabilized, as shown in FIG. 4, the optical shutter array ( The optical shutter (1a) located at the end of 10) is used as a monitor for checking the transmitted light intensity, and the LED (19) is used as a light source to supply light to the optical shutter (1a) for this monitor.
Is provided in front of the rod lens (12), and this LED (19) is
The light from the LED (19) is condensed by the rod lens (12) and is emitted to the optical shutter array (10) through the polarizer (13) by being driven by the drive unit (19a). Then, the stabilized voltages V _1, as described above in the optical shutter array (10) is applied, LED (19) light from a by polarized analyzer by light shutter (1a) for the monitor (1
5) and pass the light through the SELFOC lens array (1
6) Collect the light by the SELFOC lens array (1
A light receiving element (20) provided behind 6) is irradiated. Then, this was irradiated light is photoelectrically converted in the light receiving element (20), which was amplified by an amplifier (21), and the amplified output voltage V _X, which is preset in the reference voltage generator (22) a reference voltage V _R compared in a comparator (23), the output voltage V _X reaches the reference voltage V _R, via a switch controller (24), the controller (1
By 8) with turning on a fluorescent lamp (11), by applying a driving voltage V ₂ to the optical shutter (1), and so as to drive the optical shutter (1). Next, in the modified example shown in FIG. 5, a halogen lamp (30) is used as a light source, and the light from the halogen lamp (30) and a reflecting mirror (31) provided behind the halogen lamp (30) are passed through an infrared absorption filter. Through (32) to the optical fiber (33),
The light from the optical fiber (33) is condensed by a rod lens (12), and the light is irradiated to an optical shutter array (10) through a polarizer (13). Then, similarly to the above embodiment, the driving circuit (14) for driving the optical shutter array (10) applies a driving voltage to an appropriate optical shutter (1).
The V ₂ is applied, the optical shutter (1) polarizes the illumination light to passed through the analyzer (15), a photosensitive member charged by condensing the light by SELFOC lens array (16) (17) Irradiate on the top and record as image information. Others of this modification, the means for driving the optical shutter array (10) is substantially the same as those of the above embodiment, the stabilized voltages V ₁ to the optical shutter (1) is applied, is the transmitted light intensity After confirming the stabilization with the monitor optical shutter (1a), the driving voltage V _{2 is} applied to an appropriate optical shutter (1).
To drive the optical shutter (1). However, in this modified example, a mechanical shutter (34) is provided between the halogen lamp (30) and the infrared absorption filter (32), and until the transmitted light intensity of the optical shutter (1) is stabilized, the halogen shutter (34) is turned off. The light from the lamp (30) is blocked by the mechanical shutter (34), and after the intensity of the transmitted light of the optical shutter (1) is stabilized, the shutter controller (34) is switched via the switch controller (24).
The mechanical shutter (34) is opened according to a), and the light from the halogen lamp (30) is supplied to the optical shutter array (10). Therefore, in this modified example, the halogen lamp (30) can be turned on even before the transmitted light intensity of the optical shutter (1) is stabilized, and as in the above-described embodiment, after the transmitted light intensity of the optical shutter (1) is stabilized, in synchronization with the application of the drive voltage V ₂ is so there is no need to perform control of turning on the light source. (Embodiment 2) Embodiment 2 is also similar to Embodiment 1 in that the optical shutter is driven after applying a stabilizing voltage to the optical shutter to stabilize the transmitted light intensity. but in that of this embodiment, as shown in Figure 9 and Figure 10, until the transmitted light intensity in the optical shutter (1) as a stabilizing voltages V ₁ is stabilized, discrete optical shutter (1) A pulse voltage of the half-wave voltage Vλ / 2 is applied to the electrode (1b), and the half-wave voltage Vλ is applied to the other common electrode (1c).
A negative pulse voltage −V _Y is applied in synchronization with a pulse voltage of / 2, and a pulse voltage (Vλ / 2 + V) obtained by combining the half-wavelength voltage Vλ / 2 and the negative pulse voltage −V _Y to the optical shutter (1). _Y ) is applied. After the transmitted light intensity of the optical shutter (1) is stabilized, the negative pulse voltage −V _Y applied to the common electrode (1c) is eliminated, and the half-wave voltage Vλ / 2 is applied to the individual electrode (1b). applying a pulse voltage as the drive voltage V _2, and so as to drive the optical shutter (1). Here, the magnitude of the negative pulse voltage −V _Y applied to the other common electrode (1c) side is such that the optical shutter (1) transmits light until the transmitted light intensity of the optical shutter (1) is stabilized. to prevent transmission, as shown in FIG. 8, half-wave voltage Vlambda / 2 and voltage this and the negative voltage -V _Y is combined (Vlambda / 2
+ V _Y ) is set to be a one-wavelength voltage Vλ at which the transmitted light intensity from the optical shutter (1) becomes zero. When the optical shutter (1) is driven in this manner,
Since the light is not transmitted until the transmitted light intensity of the optical shutter (1) is stabilized, the light source is turned on in synchronization with the driving of the optical shutter as described in the first embodiment, or the light from the light source is emitted by the mechanical shutter. It is not necessary to shut off the light source, and as shown in FIG. 10, the light source can be turned on even before the transmitted light intensity of the optical shutter is stabilized. In the second embodiment, the first embodiment is also used.
As in the case of (1), the optical shutter (1a) located at the end of the optical shutter array (10) is used as a monitor, and the monitor optical shutter (1a) confirms that the transmitted light intensity is stable. I have. However, as in the first embodiment and the present embodiment, the time when the transmitted light intensity is stabilized is measured in advance without providing the monitor light shutter (1a) and confirming that the transmitted light intensity is stabilized. And stabilizing voltage
After applying the V ₁ by that time, it is also possible to so as to apply a driving voltage V _2. Example 3 In Example 3, as shown in FIG. 11, a polarizer (13) provided before and after an optical shutter (1) was used.
The direction of the plane of polarization of the light and the analyzer (14) is set to be the same, and light is transmitted when a half-wavelength voltage Vλ / 2 is applied to the optical shutter (1), contrary to the usual method. Instead, light is transmitted without applying a voltage. Then, as shown in FIG. 12, after initially by applying a half-wave voltage Vlambda / 2 DC voltage as stabilized voltage V _1, to stabilize the transmitted light intensity of the optical shutter (1), the drive voltage the optical shutter (1) as V _2, a pulse voltage of the half-wave voltage Vlambda / 2 is applied, light is not transmitted in a state where a pulse voltage to the optical shutter (1) is applied, a voltage between the pulse voltages Light is transmitted when no voltage is applied. As described above, in the third embodiment, since light is not transmitted when the half-wavelength voltage Vλ / 2 is applied to the optical shutter (1), the stabilized voltage V ₁ is applied to the optical shutter (1).
In the stage where is applied, no light is transmitted.
As in the case of (1), there is no need to turn on the light source in synchronization with the drive of the optical shutter or to block the light from the light source by the mechanical shutter, and as shown in FIG. Until it stabilizes,
The light source can be turned on. [Effects of the Invention] As described above in detail, in the optical writing device according to the present invention, before the drive voltage is applied to the optical shutter to record the image information on the irradiation object, the drive control unit controls the optical shutter. After applying the stabilizing voltage to stabilize the intensity of the transmitted light from the optical shutter, the driving voltage is applied to the optical shutter to drive the optical shutter, so that the driving voltage becomes stable through the optical shutter to which the driving voltage is applied. Light having a high transmitted light intensity is applied to an object to be irradiated. Also, while the stabilizing voltage is applied to the optical shutter as described above, the mechanical shutter is closed by the above-described shutter control means to block the light from the light source, and the intensity of the transmitted light from the optical shutter rises and becomes stable. Until it becomes
Since the light emitted from the light source is prevented from passing through the optical shutter and irradiating the illuminated object such as the photoreceptor, unnecessary irradiation of the illuminated object is eliminated. Further, in the optical writing device according to the present invention,
A light receiving element for receiving the light transmitted through the optical shutter is provided in the shutter control means, and the mechanical shutter is opened and closed based on the output of the light receiving element. Until the intensity of the transmitted light from the optical shutter rises sufficiently and stabilizes, the light from the light source is reliably blocked by the mechanical shutter, and the stable and high light is reliably transmitted through the optical shutter to which the drive voltage is applied. Light having a transmitted light intensity is applied to the object to be irradiated. As a result, in the optical writing device according to the present invention, when exposing the photosensitive member of the electrophotographic printer, the photosensitive member can be sufficiently rotated from the beginning without increasing the pulse width of the driving voltage applied to the optical shutter. Exposure can be performed, contrast can be increased without lowering the system speed of a printer or the like, and image density unevenness can be eliminated.In addition, the sensitivity of the irradiated object may vary, or the irradiated object may be deteriorated. It has an excellent effect of being reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a characteristic diagram showing a relationship between an applied voltage and transmitted light intensity in an optical shutter. FIGS. 2 and 3 show a DC voltage or pulse of a half-wavelength voltage Vλ / 2 applied to the optical shutter. FIG. 4 is an explanatory view showing a change in transmitted light intensity when a voltage is applied, FIG. 4 is a schematic view showing a structure of an electrophotographic printer used in Embodiment 1 of the present invention, and FIG. FIGS. 6 and 7 are schematic diagrams showing the structure of a modified example of the electrophotographic printer used. FIGS. 6 and 7 show a first embodiment in which a DC voltage or a pulse voltage of a half-wavelength voltage Vλ / 2 is applied as a stabilizing voltage. FIG. 8 is a timing chart showing the state of driving the shutter, FIG. 8 is a characteristic diagram showing the relationship between the applied voltage and the transmitted light intensity in the optical shutter, and FIG. And apply FIG. 10 is a timing chart showing a state in which the optical shutter is driven in the second embodiment. FIG. 11 is a diagram showing a polarization state in the third embodiment of the present invention in which the direction of the polarization plane is the same before and after the optical shutter. FIG. 12 is a perspective explanatory view showing a state in which a probe and an analyzer are provided, and FIG. 12 is a timing chart showing a state in which an optical shutter is driven in the third embodiment. [Explanation of Symbols] (1) Optical shutter (10) Optical shutter array
(20) ... light receiving element, (34) ... mechanical shutter,
(34a): Shutter controller, V _1: Stabilized voltage, V _2: Drive voltage

Continued on the front page (72) Inventor Koichi Aragaki 2-30 Azuchi-cho, Higashi-ku, Osaka-shi, Osaka Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Hirohisa Kitano 2--30 Azuchi-cho, Higashi-ku, Osaka, Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Tomohiko Masuda 2-30 Azuchicho, Higashi-ku, Osaka City, Osaka Prefecture Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-59-3416 (JP, A) JP-A-62-210778 (JP, A) JP-A-59-123366 (JP, A) JP-A-54-150151 (JP, A) JP-A-61-54965 (JP, A) JP-A-59-113414 (JP, A) JP, A) JP-A-58-93030 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/00-1/335 B41J 2/44-2/445 G03G 15 / 04-15/047 H04N 1/024-1/207

Claims (1)

(57) [Claims] In an optical writing device that guides light emitted from a light source to an optical shutter made of a material having an electro-optical effect and controls transmission of light by the optical shutter to record image information on an irradiation target, A mechanical shutter is provided in an optical path between the light source and the optical shutter, and a driving voltage is applied to the optical shutter so that a stabilizing voltage is applied to the optical shutter before image information is recorded on an irradiation target. Drive control means for stabilizing the intensity of light transmitted through the optical shutter, and while the stabilizing voltage is being applied to the optical shutter, the mechanical shutter is closed to block light from the light source, while the optical shutter Shutter control means for opening the mechanical shutter while driving voltage is being applied and controlling the light from the light source to guide the light to the optical shutter; Control means comprises a light receiving element for receiving light transmitted through the optical shutter, an optical writing device, characterized in that for opening and closing the mechanical shutter on the basis of the output of the light receiving element.