彩色显像管荫罩槽孔尺寸与热变形关系分析

Relation between Thermal Deformation of Shadow Mask and the Slot Size

荫罩是彩色显像管的分光部件,工作中因截获大量电子而发热,热变形将改变着屏电子束的位置,影响色彩对准.该文讨论荫罩槽孔尺寸与热变形的关系,对热变形引起的电子束着屏位移进行预测.首先建立较为精细的等效模型,考虑荫罩的不同区域,其孔形大小和腐蚀加工的深度不同,建立相应的等效代表单元,在保证拉伸模量等效的同时,兼顾槽、桥两个方向截面抗弯刚度的等效,因此,弹性模量是随位置变化的.在此基础上对荫罩热变形进行有限元模拟,并用摄动法讨论了弹性模量的差异对变形的影响.所得结果与生产实际一致,对于彩色显像管的设计和生产有指导意义.

Shadow mask, an electron sieve mounted in the front of CRT in color TV, is inevitably heated by the captured electrons. Thermal deformation leads to deflection of electron beams, which will spoil color purity. This paper discusses the relation between the thermal deformation of a shadow mask and its slot size, and predict the beam-landing shift. An improved equivalent structural elastic modulus with orthogonal anisotropy is proposed to construct the finite element model for the mask. The equivalence requires that the same bending stiffness across both slot and bridge are the same, and the extensional stiffness between the model and the prototype are also the same. This paper takes a large number of different representative units from the entire shadow mask according to the local geometries and erosion features of the slots to localize the equivalent elastic modulus in our model. In addition, this paper takes advantage of asymptotic method to confirm the effects of the modulus on deformation. Simulation results agree with the practice, which can be used to guide the mask design.